Eddy Probe Systems - ALBEST Probe Systems Introduction / Selection 3 Selecting An Eddy Probe System...

SKF Condition Monitoring®

Eddy Probe SystemsProbes and Drivers

Mounting Devices

Housings

Pressure Feedthroughs

Calibrators and Simulators

Accessories

EddyProbeSystemsCatalog

Table ofContents

i

Introduction/Selection 1Introduction ………………………………………………………………1

Shaft Relative Motion …………………………………………….1

Eddy Probe Systems ……………………………………………... 1Frequency Considerations ………………………………………...1

The Versatile Eddy Probe ………………………………………………..2

How It Works ……………………………………………………. 2Selecting An Eddy Probe System ………………………………………. 3

Some Eddy Probe Options ………………………………………. 3

RYTON® Based Eddy Current Transducers 5CMSS 65/CMSS 665 Series – 5mm Eddy Probe System ………………. 5CMSS 68/CMSS 668 Series – 8mm Eddy Probe System ………………. 8

CMSS 62/CMSS 620 Series – 19mm Eddy Probe System ……………. 12

Eddy Current Probe Installation Accessories 14CMSS 920 High Pressure Feedthrough ………………………………...14CMSS 911 Probe Holder With Housing ………………………………..15

CMSS 911 Dual Sensor Holder With Housing ………………………... 15

CMSS 904 Probe Holder ………………………………………………. 17CMSS 912 Dual Axial Probe Adapter ………………………………….17

CMSS 903 Series – Mounting Brackets ……………………………….. 18

CMSS 30112000 Series – Cable Packing Gland Assembly ……………19CMSS 30837800 1/2" or 3/4" NPT Probe Adapter ……………………. 19

Driver Housings 20Explosion-Proof Housings For DIN-Rail Mount Drivers ……………... 20

Weatherproof Housings ………………………………………………...21

CMSS 601 Static Calibrator 23

CMSS 748-3 Probe Gapper 24

Typical Eddy Probe Arrangement Plans 25Turbine ………………………………………………………………….25

Compressor ……………………………………………………………..25

Electric Motor …………………………………………………………..26Pump ……………………………………………………………………26

Gear Box (Double Helical Gear) ………………………………………. 27

Bearing Housing Mounting 28

Axial Probe Installation 29

Outline Dimension Drawings 305mm and 8mm Eddy Probe Outline Dimension Drawing …………….. 305mm and 8mm Eddy Probe Driver Outline Dimension Drawing ……... 31

CMSS 958 Extension Cable Outline Dimension Drawing ……………..32

Hazardous Area Information 33Area General Information ………………………………………………33Agency Approvals ……………………………………………………... 33

Intrinsic Safety (I-S) Barriers For Use With CMSS 65 and

CMSS 68 Series Eddy Probe Systems …………………………..34

Hazardous Location Information 35Classes and Divisions ………………………………………………….. 35

Electrical Sources of Ignition ……………………………………35

Hazardous Locations and the National Electrical Code ………... 35Hazardous Location Equipment …………………………………36

Hazardous Location Equipment Applications ………………….. 36

Chemical By Groups ……………………………………………………37Groups A, B, C, D, E, F, and G ………………………………… 37

Hazardous Locations Cross Reference ………………………………… 38

Industry Reference Information 38Industry Reference Information (What's In A Rating?) ……………….. 38Comparison of Specific Non-Hazardous Applications

(Outdoor Locations) ……………………………………………..38

Enclosures For Non-Hazardous Locations …………………………….. 39Comparison of Specific Non-Hazardous Applications

(Indoor Locations) ……………………………………………… 39

International Standards' IP Protection Classification ………………….. 40NEMA, UL, CSA, Versus IEC Enclosure Type Cross-Reference

(Approximate) …………………………………………………...41

Sources of Standards ……………………………………………………41

Glossary 42

EddyProbeSystemsCatalog

Table ofContents

ii

Eddy Probe Systems Introduction / Selection 1

IntroductionEffective protection of rotatingmachinery requires that the propertype of measurement be performed.The most suitable type of transducermay then be defined. Finally, specificapplication circumstances (frequenciesof interest, operating temperatures,mounting requirements) are consideredto select the optimum transducer. Thechart at right provides generalguidelines for determining the mosteffective type of measurement.

Shaft Relative MotionShaft relative motion is the radialvibration of the shaft journal relativeto the bearing. This method ofvibration measurement is preferred forjournal bearings since it directlyrelates to permissible clearances. Inmachines with relatively light rotorsand stiff heavy casings (turbines andcompressors) almost all of the shaft’svibration energy is dissipated asdisplacement (exhibit lowtransmissibility) which can only bemeasured as shaft relative motion.

An Eddy Probe, mounted to, orthrough the bearing, observes the shaftto provide this measurement. Anadditional Eddy Probe is ofteninstalled 90° from the first, in anorthogonal arrangement, to increasemonitoring and diagnostic capabilities(voting logic and shaft orbit display).

Eddy Probe SystemsThe Eddy Probe is used to measureradial or axial shaft motion. It ismounted through or to the side of abearing cap and observes the shaft’smovement relative to its mountingposition. An Eddy Probe Systemcomprises a Probe, a Driver (oscillatordemodulator), and an Extension Cable.

Eddy Probe Systems have excellentfrequency response. They have nolower frequency limit and are used tomeasure shaft axial position as well asvibration.

While Eddy Probe Systems offerexcellent high frequency response,displacement at typical blading andgear mesh frequencies is quite small(an accelerometer may be used toaugment the Eddy Probe System whenhigh frequencies are a concern).

FrequencyConsiderations

Shaft relative measurements alwaysuse Eddy Probes and are indicated interms of displacement. Bearing cap orcasing measurements, however, mayuse accelerometers or velocitytransducers, either of which may beconditioned to indicate in terms ofacceleration, velocity, or displacement.

The frequency range of interest and thedesired measurement terms are criticalfactors in transducer selection.Vibration presented in terms ofvelocity is generally accepted as avalid indication of destructive energyacross the entire range of frequencies,

whereas displacement and accelerationlevels must always be evaluatedconsidering the frequency content.

High frequency measurements (rollingbearings, gear mesh, and bladepassage) are best made using anaccelerometer and presented in termsof acceleration, which is typicallystrong at these frequencies.

Low frequency (< 15 Hz) bearing capvibrations need special treatment. Thefrequency response of most reasonablypriced Velocity Transducers startsdropping off between 10 Hz and 20 Hzand, although Accelerometerscommonly respond down to 3 Hz,acceleration is very weak at lowfrequencies. The best solution is tointegrate the Accelerometer’s signal toread out in terms of velocity. Doubleintegration to displacement wouldprovide the strongest signal but, exceptin very special cases, it is inadvisablebecause of significant low frequencyinstability associated with theintegration process.

– NOTE –

Eddy Probe, Displacement Probe and ProximityProbe are all synonyms for the same or similar

products manufactured and supplied byvarious companies.

Typical Machines

Typical Characteristics

• Stiff Bearings• High Transmissibility• Low Damping

• Small Pumps and Fans• Small Gas Turbines• Cooling Tower Fans• Most General Purpose

Machinery

SleeveRolling ElementBearing

Type

SPECIAL CONSIDERATIONS

• Large Gas Turbines• Gear Boxes, Large Fans• Boiler Feed Pumps

Casing or Bearing Cap Motion (Accelerometers, Velocity

Transducers, Twin Sensors)

Shaft Relative MotionEddy Probe Systems

• Barrel Compressors• Steam Turbines• Large Motors

• High Case: Rotor Weight Ratio

• Low Transmissibility• Medium To High

Damping

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Signal OutEddy

Probes

Driver

Driver

2 Eddy Probe Systems Introduction / Selection

The Versatile Eddy Probe

The Eddy Probe System is a fieldproven method for reliably detectingvarious machine displacementparameters. The Probe’s simplicityand rugged design enables it towithstand the temperatures andchemicals typically encountered in theharsh machine environment.

How It WorksThe tip of the Eddy Probe contains anencapsulated wire coil which radiatesthe Driver’s high frequency signal intothe observed target as a magnetic field.The Driver outputs a dc voltagerepresenting the field strength. As aconductive surface approaches the coil,eddy currents are generated on thetarget surface, which decreases thefield’s strength resulting in a decreaseof the Driver’s dc output.

Radial Motion of Rotating Shafts.

Shaft vibration is represented as avarying dc voltage which may be usedfor monitoring, balancing, or analysis.Using two Probes separated by 90°,shaft orbit may be derived and X-Yvoting logic monitoring may be used.

Companion Unit: CMMA 864Vibration Monitor

Eddy Probe Tip.

The Driver linearizes and normalizesits output to a specific sensitivity(usually 200 mV/mil) throughout itsworking range. The signal’s dc bias,representing the average probe gap,and its AC component, profilingsurface movement and irregularities, isreadily used in many applications,some which are shown in the followingdiagrams.

Differential Expansion.

The Eddy Probe is rigidly mounted tothe machine case and observes aramped section of the shaft or aperpendicular shaft collar. The dcoutput voltage represents the axialshaft position and varies as the shaftand/or case experience thermalmovement. Differential expansionmonitoring confirms acceptable rotor/case growth rates.

Companion Unit: CMMA 833 TSI/Position Monitor

Key Phasor/Speed.

As the Eddy Probe observes thepassage of a hole or keyway on a shaftor collar, the Driver outputs a voltagepulse. This pulse may be used togenerate a speed display or, along withvibration data, it can also be used toperform dynamic balancing. Multipleevents per revolution (such as a gear)may also be observed by the EddyProbe for speed determination.

Companion Unit: CMMA 881 Speedand Phase Monitor

Rod Drop.

As the piston rings, rider rings, andcylinder liners wear, allowing the rodto gradually drop, the probe gapwidens. The Driver's dc voltage outputmay be used to determine when ringsshould be turned/replaced beforedamage to the piston occurs.

Companion Unit: CMMA 833 TSI/Position Monitor

Axial (Thrust) Position.

Shaft axial (thrust) position isrepresented by the average dc voltageand is normally used for monitoring.Two Probes are recommended topermit voting protection (especially onsystems armed for automaticshutdown).

Companion Unit: CMMA 864Position Monitor

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VaryingGap

Target

Flat "Pancake" Coil

MagneticField

Eddy Probe Systems Introduction / Selection 3

Selecting An Eddy Probe System

A wide variety of SKF systems areoffered to meet the requirements ofvirtually any application. Probe rangeis limited largely by the probe’sdiameter. The standard SKF probediameters are 5mm (CMSS 65), 8mm(CMSS 68), and 19mm (CMSS 62).

The following should be consideredwhen selecting a system:

RANGE

Gap over which the system mustaccurately operate.

SENSITIVITY

Must be compatible with monitors orother companion instruments.

SYSTEM LENGTH

The physical length of the systems isapproximate to the electrical length.Excess cable in certain installations istypically coiled and tied with noharmful effects.

PROBE CASE

The size of the probe mounting casemay be a factor in some installations(several case options are availableindicated under ordering information).

Standard SKF Eddy Probe Systems.

Some Eddy ProbeOptionsARMOR

A flexible stainless steel jacketprotects the cable. Recommendedwhen the cable is not protected byconduit. Available on Probe Cablesand Extension Cables. Not compatiblewith Cable Packing Glands.

CERTIFICATION

Approved Probes and Drivers can besupplied with either nonincendive orintrinsic safetly approvals.Nonincendive products are suppliedwith FM (Factory Mutual) certificationtags attached. Intrinsically safeproducts are supplied with tripleagency approval certification tagsattached (EECS [BASEEFA], FM[Factory Mutual Systems] and CSA).

CE Mark

Beginning January 1996, EuropeanCommunity requires equipment sold intheir area to be a CE marked product.Because sensors have an activecomponent such as the integratedcircuit amplifier, the sensor shouldhave the CE mark.

A Word About . . .PROBE TIPS

SKF uses RYTON® for Eddy Probetips because it is simply the bestmaterial for the job. RYTON has highdimensional stability reducing probe

coil shape variations with temperatureand humidity and maintaining systemaccuracy, linearity, and resolution.RYTON is a “super plastic” that hasno known solvent below +400°F(+205°C) and therefore highly resistantto the acids, bases and solventshandled by process machinery.

INSTALLATION

Major considerations includetemperatures, pressures, andmechanical stress to which the Probe,Driver, and cables are subjected. It isessential that the Probe be rigidlymounted, yet easily adjusted (SKFmounting accessories are ideal forthis). If long cable runs between theDriver and Monitor are required,consult the table to the right todetermine the maximum recommendedwire length (use 3-conductor shieldedwire).

TARGET MATERIAL

Standard systems are calibrated toobserve 4140 steel. As recommendedby API Standard 670, Probecalibration should be verified on atarget with the same electricalcharacteristics as the shaft. The SKFCMSS 601 Static Calibrator and theDriver trim control, permit verificationand convenient field calibration withina ± 5% range on the shaft itself.Response is dependent upon theconductance of the target material, asillustrated on the chart. Drivers maybe special ordered for calibratedresponse to different metal types.Customers will be requested to providesamples of the metal types.

RUNOUT

Because the Eddy Probe works on theprinciple of conductivity, shaftirregularities (flat spots, scratches,plating, hardness variations, carboninclusions, magnetized regions, etc.)may produce false vibration signals.API Standard 670 recommendscombined total electrical andmechanical runout does not exceed0.25 mils maximum. Someirregularities, such as plated shafts,cannot be reduced to an acceptablelevel with traditional methods(peening, knurling, etc.).

System response varies with the targetmaterial.

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Usable System StandardSystem Range Sensitivity Length Case Comments

CMSS 65/CMSS 665 80 Mils 200 mV/Mil 5 Meters 1/4-28 Standard SystemCMSS 68/CMSS 668 90 Mils 200 mV/Mil 5 Meters 3/8-24 Meets Intent Of API 670CMSS 68/CMSS 668-1 90 Mils 200 mV/Mil 10 Meters 3/8-24 Long System LengthCMSS 68/CMSS 668-2 90 Mils 200 mV/Mil 15 Meters 3/8-24 Long System LengthCMSS 62/CMSS 620-2 60-300 Mils 50 mV/Mil 10.8 Meters 1"–12 UNF Long RangeCMSS 68/CMSS 668-5 15-160 Mils 100 mV/Mil 10 Meters 3/8-24 Long Range

Wire Size Distance(AWG) (Maximum)

22 500 Feet (150 meters)20 1,000 Feet (300 meters)18 2,000 Feet (600 meters)16 3,000 Feet (900 meters)

Gap From Probe Tip To Test Article (mils)

Out

puts

(V

dc)

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10 20 30 40 50 60 70 80 90 100

-22

-20

-18

-16

-14

-12

-10

-8

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4 Eddy Probe Systems Introduction / Selection

Selecting An Eddy Probe System

INTRINSIC SAFETY

SKF Monitors provide current limitedpower to Eddy Probe Systems whichmeet safety requirements of mostapplications. However, if intrinsicsafety barriers (Zener barriers) will beused, consult the local salesrepresentative to ensure range,linearity, and power requirements willbe met.

API STANDARD 670

The American Petroleum Institute haspublished Standard 670 as an aid to theprocurement of standardized non-contacting vibration, axial position,and temperature monitoring systems.The standard is based on theaccumulated knowledge andexperience of petroleum refiners andmonitoring system manufacturers.API Standard 670 is a valuablereference tool for all machinery usersand manufacturers, and is highlyrecommended as a guide for defining,purchasing, and installing machinerymonitoring systems.

API 670 was written to define reliableprotection systems for rotatingequipment operating in the harshconditions found in oil production,refining, and chemical processing.SKF RYTON based Eddy CurrentProbes were designed using a uniquetemperature chamber to test the Probesover the wide temperature rangerequired by API. The outputsensitivity of conventional EddyCurrent Probe systems typically fallsoff as temperature increases. A uniqueProbe winding technique wasdeveloped by SKF that strives tomaintain output sensitivity over thespecified temperature range.

“Super tough” Eddy Current Probesystems are thoroughly field tested andproven, with thousands of unitsinstalled.

SKF has been using RYTON in itstransducer designs for many years.RYTON’s strength approaches that ofmetal. The material is now beginningto be used in the manufacture ofautomobile engine camshafts. That’swhat we mean when we say “Supertough”.

SKF Eddy Current Probes are availablein a variety of case mountingconfigurations and length options tomeet difficult installation requirements.

RYTON is impervious to any solventat temperatures up to +400°F(+205°C). For this reason, SKF DriverHousings are also made of this samesuper tough material. An addedbenefit is that there is no longer a needto electrically isolate drivers duringinstallation to prevent troublesomeground loops. RYTON’s provenresistance to extreme harshenvironments protects the complexelectronics required to operate EddyCurrent Probes. An internal sealingsystem protects these components frommoisture ingression and corrosion.This increases system reliability byeliminating the need to totallyencapsulate these components. Due toits unique construction, both the DriverHousing and the internal circuits reactto severe thermal excursions at thesame rate. This reduces internalstresses created by routine machinerytransients or load changes, providingfor a longer driver life.

SKF Drivers are EMI/RFI shielded,and the mounting scheme allows themto fit the same “footprint” as previousSKF Driver Housings, or they can besnapped onto type C-DIN rails for highdensity applications and quickinstallation. The compressionconnector for terminating the powerand signal wiring further aids in theease and cost of installation. A fixedconnector version is also available.

SKF Eddy Current Probe systems areconstantly temperature andperformance tested in a continuingeffort to improve what is already thebest Probe available for themeasurement of vibration in rotatingequipment. They are available witharmored and fiberglass sleeving, andmay be offered EECS (BASEEFA)/CSA/FM certified.

The small tip diameter (5mm) of theCMSS 65 Eddy Current Probesystems, coupled with the stringentcontrols under which they areproduced, effectively reducescalibration error due to shaft curvature.This makes the CMSS 65 anexceptional choice for measuringvibration in small diameter shafts. TheCMSS 65 is available in 5 metersystems (Probe with Integral Cable, ora combination of Probe Cable andExtension Cable) and has a typicalusable range of 10 mils to 90 mils witha 200 mV/mil sensitivity. A specificCMSS 665 Driver is required for eachof the standard length systems (refer tochart on page 3).

The larger tip diameter (8mm) of theCMSS 68 SKF Transducer is used forlarge diameter shafts as well as longrange axial position (thrust)measurements. The CMSS 68 isavailable in 5, 10 or 15 meter systemsand has a typical usable range of 10mils to 100 mils with a 200 mV/mil(7.87 V/mm) sensitivity. The CMSS668-5 Driver provides a usable rangeof 15 mils to 160 mils with asensitivity of 100 mV/ mil (3.94 V/mm); it is available only as a 10 metersystem.

Length conversion table.Temperature conversion table.

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Fahrenheit to Celsius: °C = 5/9 (°F – 32)Celsius to Fahrenheit: °F = 9/5 (°C) + 32

°F°C °C °F

-40.0 -40.0 -40.0-28.9 -20.0 -4.0-23.3 -10.0 +14.0-20.6 -5.0 23.0-17.8 0 32.0-15.9 +5.0 41.0-12.2 10.0 50.0-6.7 20.0 68.0-1.1 30.0 86.0

°F°C °C °F

+4.4 40.0 104.010.0 50.0 122.015.6 60.0 140.021.1 70.0 158.026.7 80.0 176.032.2 90.0 194.037.8 100.0 212.093.3 200.0 392.0

Conversion Between °F and °C

1 Mils = 25.4 Microns 5 Mils = 127.0 Microns 10 Mils = 254.0 Microns 20 Mils = 508.0 Microns 30 Mils = 762.0 Microns 40 Mils = 1.0160mm 50 Mils = 1.2700mm 60 Mils = 1.5240mm 70 Mils = 1.7780mm

80 Mils = 2.0320mm 90 Mils = 2.2860mm 100 Mils = 2.5400mm 110 Mils = 2.7940mm 120 Mils = 3.0480mm 130 Mils = 3.3020mm 140 Mils = 3.5560mm 150 Mils = 3.8100mm

Mils × (25.4 × 10-6) = MicronsMicrons ÷ (25.4 × 10-6) = Mils

0.5 Meters ≈ 20 Inches (1.7 Feet) 1.0 Meters ≈ 39 Inches (3.3 Feet) 5.0 Meters ≈ 196 Inches (16.0 Feet) 10.0 Meters ≈ 393 Inches (33.0 Feet) 15.0 Meters ≈ 590 Inches (49.0 Feet)

CMSS 65 / CMSS 665 Series System 5

CMSS 65/CMSS 665 Series 5mm Eddy Probe SystemRYTON® – Based Eddy Current Transducers

Option now available witheither the standardremovable/reversibleconnector or the optionalpermanent fixedconnector.

SpecificationsThe following specifications apply to acomplete CMSS 65 Eddy CurrentProbe System comprising a CMSS 65Eddy Current Probe, a CMSS 958Extension Cable and a CMSS 665 orCMSS 665P Driver. Thesespecifications may vary with differentoptions and systems configurations.

ELECTRICAL

Usable Range: 80 mils (10 mils to 90 mils)

Sensitivity: 200 mV/mil; ± 5% of 200 mV/mil, (-24 Vdc supply) at +73°F(+23°C)

Linearity: ± 1 mil of best straight lineover 80 mil range of unit at +73°F(+23°C)

Frequency Range: DC to 600,000 CPM;down maximum of 3 dB at 600,000CPM

Driver Signal Output:

Impedance: Minimum calibrated loadresistance of 3k Ω; output isprotected against miswiring

Voltage: Nominal 200 mV/milcorresponding to -18 Vdc at 90mils with -24 Vdc supply

Interchangeability: Probes, ExtensionCables and Drivers may beinterchanged with 5% or less

performance change withoutrecalibration. All units factorycalibrated at +73°F (+23°C). Trimcalibration adjustment on Driverprovides duplication of characteristicsafter replacement of any component.

Power Supply Requirements: 15 mAfrom -24 Vdc to -30 Vdc

ENVIRONMENTAL ANDMECHANICAL

CMSS 65 Eddy CurrentProbe

Operating Temperature Range:-30°F to +250°F (-35°C to +120°C)

EECS (BASEEFA) tagged are limitedto +212°F (+100°C) maximum.

Differential Pressure: To 60 psi

Case Material: 300 Stainless Steel

Tip Material: RYTON®

Connectors: Nickel plated stainless steel;weatherproof, sealable

Cable: Coaxial with Teflon® insulation;High tensile and flexible strength

Mounting: Any position; recommendclearance of 1/2 Probe Tip diameteraround the Probe Tip to maintainfactory calibration.

CMSS 665 and CMSS 665PDriver


Connections: (Power, Signal, GND) Fiveterminal removable and reversiblecompression terminal block acceptingup to 14 AWG wire. Threeconnections necessary per block (-24Vdc; GND; Signal). The CMSS 665Phas a permanent fixed connector withsame connection characteristics.

Mounting: C-DIN Rail Mount which boltsonto Driver enclosure, or the standardfour number 10 clearance holes in asquare on (2.5") 63mm centers.

CMSS 958 Extension Cable

Temperature ranges, connectors, cablesame as CMSS 65 Eddy Current Probe.

EECS (BASEEFA)Approved

FMCSA

6 CMSS 65 / CMSS 665 Series System

CMSS 65/CMSS 665 Series 5mm Eddy Probe System

Ordering Information

Part 1: Eddy Current Probe (SKF Standard: CMSS 65-002-00-12-10)

– NOTE –

See catalog page 34 for recommended Intrinsic

Safety (I-S) Barriers and entity parameters.

DIMENSIONS IN INCHES, EXCEPT AS NOTED

BA

5.0mm

6.3mm

0.205" Dia.1/4–28 OR M8 X 1 Thread

Armor (Optional)

0.28" Maximum DiameterC

STANDARD MOUNT CASE

5.0mm

0.348" (8.8mm)0.215" (5.5mm)

1.200"(30.5mm)

3/8–24 Thread UNF 2A7/16" HEX

REVERSE MOUNT CASE

CMSS 65 0 RM 12

BUTTON (DISK) PROBE

0.375"Diameter

0.190"Diameter

0.100"

0.250"

0.101"Diameter

0.030"

CMSS 65 E 00 00

CableProbe

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2.50"(6.35cm)

3.00"(7.62cm)

2.50"(6.35cm)

0.25" Clearance Hole For Mounting With Number 10 Hardware

3.00"(7.62cm)

1.60"(4.06cm)

CONNECTOR:Stainless Steel

Jack-Type Mates With CMSS 958 Extension Cable

REMOVABLE OR PERMANENT FIXED CONNECTOR:Terminal Strip Type Rated For 250 V, 10 AMPS 14 AWG. Maximum Wire Size

+1: Length is Nominal Electrical:physical length may vary.

Compatible Systems:

0.5m Probe:5.0m System:CMSS 958 - XX - 045/CMSS 665

1.0m Probe:5.0m System: CMSS 958 - XX - 040/CMSS 665

5.0m Probe:5.0m System: CMSS 665

The 5A units have integral cable and mate directly to the Driver.

CMSS 65

CABLE

Standard 00Armored 01Fiberglass Sleeved 02CSA/FM/EECS 07

(BASEEFA)(IntrinsicallySafe) Certified

CSA/FM/EECS 08(BASEEFA)(IntrinsicallySafe) Certifiedand Armored

FM (non-incendive) 09FM (non-incendive) 0B

Armored

2 1/4–28 Threads(Standard)

3 M8 X 1 Threads0 3/8–24 Threads1 M10 X 1 Threads4 No CaseE Button Probe

(Fiberglass)

CASE "C" OVERALLLENGTH +1

05 0.5 Meter10 1.0 Meter

(Standard)5A 5.0 Meter

Fully Threaded 000.1 Inches To 01

5.0 Inches ToUnthreaded 50

5.1 Inches To 519.9 Inches To

99Reverse Mount RM

3/8–24 Thread

Standards:No Case 000.8 Inches 081.2 Inches 121.5 Inches 152.0 Inches 202.5 Inches 253.0 Inches 304.0 Inches 404.7 Inches 476.0 Inches 609.0 Inches 90

SPECIALS0.9 To 5.9 09

Inches To59

9.1 To 9.9 91Inches To

99

"A" UNTHREADEDCASE LENGTH

"B" CASE LENGTH

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Part 2: Extension Cable (SKF Standard: CMSS 958-00-040)

Part 3: Driver (SKF Standard: CMSS 665)

Drivers containing the "P" in the model number denote those models withpermanent fixed connector.

CMSS 665-16-XX/CMSS 665P-16-XX

CSA/FM/BASEEFA (IntrinsicallySafe) Certified Driver for 5.0m Systemcalibrated for shaft materials other thanstandard 4140 stainless steel. Use withCSA/FM/BASEEFA (IntrinsicallySafe) Certified 1.0m CMSS 65 Probeand 4.0m CMSS 958 Extension Cable.For intrinsic safety installations driversmust be installed with intrinsic safety(I-S) barriers.

Usable Range: Best attainable for specificshaft material provided. Customer toprovide identification of shaft materialand sample (approximately 2.0"diameter disk, 0.5" thick). Range notexpected to exceed the 45 mils ofstandard unit.

Sensitivity: 200 mV/mil, ± a to bedetermined (TBD) percentage of 200mV/mil dependent on the shaft samplematerial (-24 Vdc supply).

Linearity: ± the minimum deviation (inmils) from the best straight lineattainable for the sample shaft materialprovided.

CMSS 665-20-00/CMSS665P-20-00

FM (non-incendive) Certified Driverfor the 5.0m System. Use with FM(non-incendive) Certified 1.0m CMSS65 Probe and CMSS 958 ExtensionCable. The installed system is FMapproved for Class 1, Division 2,Groups A, B, C, and D whenconnected in accordance with NationalElectric Code®.


Sensitivity: 200 mV/mil, ± 5% of 200 mV/mil, (-24 Vdc supply) at +73°F(+23°C)

Linearity: ± 1 mil of best straight line over80 mil range of unit at +73°F (+23°C)

– NOTE –

All circuit boards used in SKF CMSS 665 Series

Drivers are conformal coated as standard

procedure.

CMSS 665/CMSS 665P

SKF Standard (200 mV/mil). Use with1.0m Probe and 4.0m Extension Cable,0.5m Probe and 4.5m Extension Cableor 5.0m Probe.

CMSS 665-8/CMSS 665P-8

Specifications same as standard driver,that is also filled with potting materialto provide additional measure ofprotection when operated in adverseenvironmental conditions (200 mV/mil).

CMSS 665-16-9/CMSS 665P-16-9

CSA/FM/BASEEFA (IntrinsicallySafe) Certified Driver for 5.0mSystem. Use with CSA/FM/BASEEFA (Intrinsically Safe)Certified 1.0m CMSS 65 Probe and4.0m CMSS 958 Extension Cable. Forintrinsic safety installations driversmust be installed with intrinsic safety(I-S) barriers.


Sensitivity: 200 mV/mil, ± 5% of 200 mV/mil at +73°F (+23°C) (-24 Vdcsupply)

Linearity: ± 1 mil from best straight lineover 45 mil range at +73°F (+23°C)

CMSS 958

CABLE

Standard 00Armored 01Fiberglass Sleeved 02CSA/FM/EECS (BASEEFA) 09

(Intrinsically Safe) CertifiedCSA/FM/EECS (BASEEFA) 0A

(Intrinsically Safe) Certifiedand Armored

FM (non-incendive) 0HFM (non-incendive) Armored 0J

CMSS 665, 2.0m CMSS 65 030CMSS 665, 1.0m CMSS 65 040CMSS 665, 0.5m CMSS 65 045

LENGTH (Compatible System Listed)

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CMSS 68/CMSS 668 Series 8mm Eddy Probe SystemRYTON® – Based Eddy Current Transducers

Option now available witheither the standardremovable/reversibleconnector or the optionalpermanent fixedconnector.

SpecificationsThe following specifications apply to acomplete CMSS 68 Eddy CurrentProbe System comprising a CMSS 68Eddy Current Probe, a CMSS 958Extension Cable and a CMSS 668Driver. These specifications may varywith different options and systemsconfigurations.

ELECTRICAL

Usable Range: 90 mils (10 mils to 100mils)

Sensitivity: 200 mV/mil; ± 5% of 200 mV/mil, (-24 Vdc supply) at +73°F(+23°C)


Frequency Range: DC to 600,000 CPM;down maximum of 3 dB at 600,000CPM


Impedance: Minimum calibrated loadresistance of 3k Ω; output isprotected against miswiring

Voltage: Nominal 200 mV/milcorresponding to -18 Vdc at 90mils with -24 Vdc supply

Interchangeability: Probes, ExtensionCables and drivers may beinterchanged with 5% or less

performance change withoutrecalibration. All units factorycalibrated at +73°F (+23°C). Trimcalibration adjustment on Driverallows duplication of exactcharacteristics after replacement ofany component.

Power Supply Requirements: 15 mAfrom -24 Vdc to -30 Vdc


CMSS 68 Eddy CurrentProbe


EECS (BASEEFA) tagged are limitedto +212°F (+100°C) maximum.

Differential Pressure: To 60 psi


Tip Material: RYTON®

Connectors: Nickel plated stainless steel;weatherproof, sealable

Cable: Coaxial with Teflon® insulation;High tensile and flexible strength

Mounting: Any position; recommendclearance of 1/2 Probe Tip diameteraround the Probe Tip to maintainfactory calibration.

CMSS 668 and CMSS 668PDriver


Connections: (Power, Signal, GND) Fiveterminal removable and reversiblecompression terminal block acceptingup to 14 AWG wire. Threeconnections necessary per block (-24Vdc; GND; Signal). The CMSS 668Phas a permanent fixed connector withsame connection characteristics.

Mounting: C-DIN Rail Mount which boltsonto Driver enclosure, or the standardfour number 10 clearance holes in asquare on (2.5") 63mm centers.


Temperature ranges, connectors, cablesame as CMSS 68 Eddy Current Probe.

EECS (BASEEFA)Approved

FMCSA

+1: Length is Nominal Electrical:physical length may vary.

Compatible Systems:

0.5m Probe:5.0m System:CMSS 958 - XX - 045/CMSS 668

1.0m Probe:5.0m System: CMSS 958 - XX - 040/CMSS 668

5.0m Probe:5.0m System: CMSS 668

10.0m Probe:10.0m System: CMSS 668-1

15.0m Probe:15.0m System: CMSS 668-2

The 5A, AA, FA, units have integral cable and mate directly to the Driver.

CABLE

Standard 00Armored 01Fiberglass Sleeved 02CSA/FM/EECS 07

(BASEEFA)(IntrinsicallySafe) Certified

CSA/FM/EECS 08(BASEEFA)(IntrinsicallySafe) Certifiedand Armored

FM (non-incendive) 09FM (non-incendive) 0B

Armored

0 3/8–24 Threads(Standard)

1 M10 X 1 Threads4 No CaseE Button Probe

(Fiberglass)

CASE "C" OVERALLLENGTH +1

05 0.5 Meter10 1.0 Meter

(Standard)5A 5.0 MeterAA 10.0 MeterFA 15.0 Meter

Fully Threaded 000.1 Inches To 01 5.0 Inches To

Unthreaded 505.1 Inches To 51

9.9 Inches To99

Reverse Mount RM3/8–24 Thread

Standards:No Case 000.8 Inches 081.2 Inches 121.5 Inches 152.0 Inches 202.5 Inches 253.0 Inches 304.0 Inches 404.7 Inches 476.0 Inches 609.0 Inches 90

SPECIALS0.9 To 5.9 09

Inches To59

9.1 To 9.9 91Inches To

99


"B" CASE LENGTH

CMSS 68AAAAAA

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BUTTON (DISK) PROBE

0.500"Diameter

0.300"Diameter

0.200"

0.515"

0.110"Diameter

0.091"

CMSS 68 E 00 00

CableProbe

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4VG

ND

SIG

GN

D-2

4V

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A A

A A

CMSS 668

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2.50"(6.35cm)

3.00"(7.62cm)

2.50"(6.35cm)

0.25" Clearance Hole For Mounting With Number 10 Hardware

3.00"(7.62cm)

1.60"(4.06cm)



REMOVABLE OR PERMANENT FIXED CONNECTOR:Terminal Strip Type Rated For 250 V,10 AMPS 14 AWG. Maximum Wire Size


BA

8.0mm

7.0mm

0.324" Dia.3/8–24 OR M10 X 1 Thread

Armor (Optional)

0.28" Maximum DiameterC

STANDARD MOUNT CASE

8.0mm

0.348" (8.8mm)0.275" (6.9mm)

1.200"(30.5mm)

3/8–24 Thread UNF 2A7/16" HEX

REVERSE MOUNT CASE

CMSS 68 0 RM 12





– NOTE –

See catalog page 34 for recommended Intrinsic

Safety (I-S) Barriers and entity parameters.

AAAACMSS 958

CABLE

Standard 00Armored 01Fiberglass Sleeved 02CSA/FM/EECS (BASEEFA) 09

(Intrinsically Safe) CertifiedCSA/FM/EECS (BASEEFA) 0A

(Intrinsically Safe) Certifiedand Armored

FM (non-incendive) 0HFM (non-incendive) 0J

Armored

CMSS 668, 1.0m CMSS 68 040CMSS 668, 0.5m CMSS 68 045CMSS 668-1, 1.0m CMSS 68 090CMSS 668-1, 0.5m, CMSS 68 095CMSS 668-2, 1.0m, CMSS 68 140

LENGTH (Compatible System Listed)

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CMSS 668/CMSS 668P

SKF Standard (200 mV/mil). Use with1.0m Probe and 4.0m Extension Cable,0.5m Probe and 4.5m Extension Cableor 5.0m Probe.


Driver for 10.0m System (200 mV/mil). Use with 1.0m Probe and 9.0mExtension Cable or 10.0m Probe.


Sensitivity: 200 mV/mil, ± 10% of 200mV/mil (-24 Vdc supply) at +73°F(+23°C)

Linearity: ± 1.5 mil from best straight lineat +73°F (+23°C )


Driver for 15.0m System (200 mV/mil). Use with 1.0m Probe and 14.0mExtension Cable or 15.0m Probe.


Sensitivity: 200 mV/mil, ± 10% of 200mV/mil (-24 Vdc supply) at +73°F(+23°C )

Linearity: ± 1.5 mil from best straight lineover 90 mil range at +73°F (+23°C )


Driver for extended range (15 mils to160 mils) used with 10.0m System.Use with 1.0m Probe and 9.0mExtension Cable or 10.0m Probe.


Sensitivity: 100 mV/mil, ± 10% of 200mV/mil (-24 Vdc supply) at +73°F(+23°C)



Specifications same as standardDriver, that is also filled with pottingmaterial to provide additional measureof protection where operated inadverse environmental conditions (200mV/mil).

CMSS 668-16-9/CMSS 668P-16-9

CSA/FM/BASEEFA (IntrinsicallySafe) Certified Driver for 5.0mSystem. Use with CSA/FM/BASEEFA (Intrinsically Safe)Certified 1.0m CMSS 68 Probe and4.0m CMSS 958 Extension Cable. Forintrinsic safety installations driversmust be installed with intrinsic safety(I-S) barriers.


Sensitivity: 200 mV/mil, ± 5% of 200 mV/mil (-18 Vdc or -24 Vdc supply) at+73°F (+23°C)


– NOTE –



procedure.





CMSS 668-16-15/CMSS668P-16-15

CSA/FM/BASEEFA (IntrinsicallySafe) Certified Driver for 10.0mSystem. Use with CSA/FM/BASEEFA (Intrinsically Safe)Certified 1.0m CMSS 68 probe and9.0m CMSS 958 Extension Cable. Forintrinsic safety installations driversmust be installed with intrinsic safety(I-S) barriers.


Sensitivity: 200 mV/mil, ± 10% of 200mV/mil (-18 Vdc or -24 Vdc supply)at +73°F (+23°C)

Linearity: ± 1.5 mil from best straight lineover 60 mil range at +73°F (+23°C)

CMSS 668-16-XX/CMSS668P-16-XX

CSA/FM/BASEEFA (IntrinsicallySafe) Certified Driver for 5.0m Systemcalibrated for shaft materials other thanstandard 4140 stainless steel. Use withCSA/FM/BASEEFA (IntrinsicallySafe) Certified 1.0m CMSS 68 probeand 4.0m CMSS 958 Extension Cable.For intrinsic safety installations driversmust be installed with intrinsic safety(I-S) barriers.

Usable Range: Best attainable for specificshaft material provided. Customer toprovide identification of shaft materialand sample (approximately 2.0"diameter disk, 0.5" thick). Range notexpected to exceed the 60 mils of thestandard unit.

Sensitivity: 200 mV/mil, ± a to bedetermined (TBD) percentage of 200mV/mil dependent on the shaft samplematerial (-18 Vdc or -24 Vdc supply).

Linearity: ± the minimum deviation (inmils) from the best straight lineattainable for the sample shaftmaterial provided.

CMSS 668-20-00/CMSS668P-20-00

FM (non-incendive) Certified Driverfor the 5.0m System. Use with FM(non-incendive) Certified 1.0m CMSS65 Probe and CMSS 958 ExtensionCable. The installed system is FMapproved for Class 1, Division 2,Groups A, B, C, and D whenconnected in accordance with NationalElectric Code®.


Sensitivity: 200 mV/mil, ± 5% of 200 mV/mil, (-24 Vdc supply) at +73°F(+23°C)


– NOTE –



procedure.



For long range (wide gap)measurements

• 60 mils to 300 mils usablerange at 50 mV/mil (1.96 V/mm)sensitivity

• 10.8 meter overall cablelengths

• Dependable eddy currentoperation

• Readily interchangeable on-site

• Durable, high-temperatureprobe tip

• Rugged long life connectors

The CMSS 62 Eddy Probe, when usedwith a CMSS 620-2 Driver, has ausable range that is typically 60 mils to300 mils. The standard outputsensitivity of the system is 50 mV/mil(1.96 V/mm).

The CMSS 62 packs a long range intoa rugged industrial probe. It is usedextensively in those applicationsinvolving large position measurement.

Differential expansion measurement isan ideal application for the CMSS 62.

The CMSS 62 is available in severalprobe case configurations andenvironmental options to meet a widerange of installation requirements.

SpecificationsThe following specificationsapply to a system including theCMSS 62 Eddy Probe, CMSS620-2 Driver and CMSS 900Extension Cable.

ELECTRICAL

Usable Range: 60 mils to 300 mils

Sensitivity: 50 mV/mil, ± 10%(1.96 V/mm) (-24 Vdc supply)at +73°F (+23°C)

Linearity: ± 2 mil of best straightline from 80 mils to 280 milsgap, ± 10% of 50 mV/milsensitivity from 80 mils to 280mils absolute gap at +73°F(+23°C)

Frequency Range: Static to600,000 CPM; down to 3 dB at600,000 CPM


Impedance: 30 ΩCurrent: 4 mA maximum

Voltage:

Nominal: 50 mV/mil

Maximum Output: -19 Vwith -24 V supply

Power: -24 Vdc

CMSS 620-2 Driver


Calibration Probe Temperature:+73°F (+23°C)

Connections (Power, Output,Common): Three terminal barrier strip

(accepts #6 spade lugs)

Mounting Holes: Four #10 clearance holesin a square on 2.5" (63mm) centers

Interchangeability: Probes and Driversmay be interchanged with 10% or lessperformance change withoutcalibration. All units factorycalibrated. Trim calibrationadjustment on Driver allowsduplication of replacement.


CMSS 62 PROBE



Connections: Stainless Steel. Weather-proof, sealable.

Cable: Coaxial with Teflon® insulation.High tensile and flexural strength.

Mounting: Any position



Connections: Stainless Steel. Weather-proof, sealable.

Cable: Coaxial with Teflon® insulation.High tensile and flexural strength.

– NOTE –

Performance specifications are based on a 4140

steel target. Consult sales representative for

calibration requirements on other materials.

20

18

16

14

12

10

8

6

4

2

0

Out

put (

Vol

ts)

80 10060 140 160 180 200 220 240 260 280 300

Gap (mils)

120

Output vs. Gap

60

55

50

45

40

35

Sen

sitiv

ity (

mV

/mil)

Sensitivity vs. Gap

80 10060 140 160 180 200 220 240 260 280 300

Gap (mils)

120

± 10%

Typical CMSS 62/CMSS 620-2 Performance


BUTTON (DISK) PROBE

CMSS 62 5 00 00

#8 MountingHoles (3 Places)

120°

0.750"(19.1mm)

1.312"(33.3mm)

Cable

Mounting Surface

19.0mm

1.500" Diameter(38.1mm)

BA

19.0mm

15.2mm

0.900" Diameter(22.8mm)

1–12 UNF 2A Thread

Armor (Optional)

0.28" Maximum Diameter

C

STANDARD MOUNT CASE




Part 3: Probe Driver (SKF Standard: CMSS 620-2)

Use with: 1.0 Meter Probe and 9.8 Meter Extension Cable2.0 Meter Probe and 8.8 Meter Extension Cable4.0 Meter Probe and 6.8 Meter Extension Cable


CMSS 900

Standard 0Armored 1Radiation Resistant 2Armored and Radiation 3

ResistantFiberglass Sleeving 4Fiberglass Sleeving and 5

Radiation Resistant

CABLE

CONNECTORS

Both Straight 0One Right Angle 1Both Right Angle 2

6.8 Meters: Use With 4.0 Meter 068 Probe and CMSS 620-2 Driver8.8 Meters: Use With 2.0 Meter 088 Probe and CMSS 620-2 Driver9.8 Meters: Use With 1.0 Meter 098 Probe and CMSS 620-2 Driver

LENGTH *

Radiation resistant probes must use radiation resistant extension cables.

* NOTE: Probe overall lengths and extension cable lengths are nominal and will vary to meet electrical interchangeability requirements. Contact sales representative for unlisted options.

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CALIBRATIONTEMPERATURE

Standard 0Radiation Resistant 1Armored 4Armored and Radia- 5

tion ResistantFiberglass Sleeved 8Radiation Resistant, 9

Fiberglass Sleeved

CABLE

75°F; Operation 0< 200°F (UseCMSS 620-2 Driver)

0 1–12 UNF 2AThreads(Standard)

4 No Case5 Button (Disk)

Probe6 Right Angle

Cable Exit1–12 UNF 2A Threads

CASE

00 Fully Threaded01 0.1 InchesTo To50 5.0 Inches

Unthreaded


"B" CASE LENGTH

Standards:00 No Case10 1.0 Inches15 1.5 Inches30 3.0 Inches35 3.5 Inches50 5.0 Inches

10 1.0 Meter20 2.0 Meters

(Standard)40 4.0 Meters

"C" OVERALLLENGTH

CMSS 62AAAAAA

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INSIDE MACHINEOUTSIDE MACHINE

5-Meter Systems: CMSS 665 CMSS 958-00-030 (3.0 Meters)CMSS 668

10-Meter Systems: CMSS 668-1 CMSS 958-00-080 (8 Meters)

15-Meter Systems: CMSS 668-2 CMSS 958-00-130 (13 Meters)

Driver Extension Cable Feedthrough Eddy Probe

CMSS 665CMSS 668

Driver Feedthrough Eddy ProbeAA AAAA AA

AA AAAA AACMSS 920-x0xx-10xxxx-010 (1.0 Meters) CMSS 65-00x-xx-xx-10 (1.0 Meters)

CMSS 68-00x-xx-xx-10 (1.0 Meters)

CMSS 920-x0xx-10xxxx-010 (1.0 Meters) CMSS 65-00x-xx-xx-10 (1.0 Meters) CMSS 68-00x-xx-xx-10 (1.0 Meters)

CMSS 920-x0xx-10xxxx-010 (1.0 Meters) CMSS 68-00x-xx-xx-10 (1.0 Meters)

CMSS 920-x0xx-45xxxx-000 (4.5 Meters) CMSS 65-00x-xx-xx-05 (0.5 Meters) CMSS 68-00x-xx-xx-05 (0.5 Meters)

14 Eddy Current Probe Installation Accessories

CMSS 920 High Pressure Feedthrough

HIGH PRESSURE SIDE LOW PRESSURE SIDE

Armor Optional Armor Optional3/4" NPT Both Ends

Cable 1 High Pressure End LengthCable 2/3 High Pressure End Length

Cable LengthCable Length

1.50"1.25"The SKF ConditionMonitoring Model CMSS920 is a low cost, generalpurpose High PressureFeedthrough. The CMSS920 is principally used toprovide a cable exit forinternally mounted EddyProbes in high pressureareas. The unit is availablein configurations for one,two, or three cables and the cablelengths on the high pressure and lowpressure side may be specified asrequired to meet particular Eddy ProbeSystem configurations. The internalmodular construction allowsconfiguration to customer’sspecifications.

The CMSS 920’s bidirectionalpressure rating of 2,000 psi enables theunit to withstand both pressure andvacuum, a critical requirement forrefrigeration units which aredehumidified under vacuum andpressurized in normal operation. The

3/4 inch NPT mounting threads oneither end enables the CMSS 920 to beinstalled in a smaller hole. An optional1-inch NPT thread adapter is availableand may replace other high pressurefeedthroughs with the CMSS 920.

SpecificationsPHYSICAL

Case Material: Type 303 stainless steel

Mounting: Any position, 3/4" NPT threads

Cable Length of High Pressure End:Increments of 0.1 meter (Recommendminimum of 0.2 meters)

Cable Quantity: 1, 2, or 3 cables

Cable Armor: Available

Customer ID: 1.5" clear heat-shrink

Torque: 60–80 foot-pounds

DYNAMIC

Pressure/Vacuum: 0 to 2,000 psibidirectional

Electrical Cable Length: As required tomeet Eddy Probe Systemconfiguration

ENVIRONMENTAL


Compatible CMSS 920 Systems

CMSS 920

ENVIRONMENT

CABLE QUANTITY

1 Cable 12 Cables 23 Cables 3

Standard 0

ARMOR

No Armor 0High Pressure End Armor 1Low Pressure End Armor 2Both Ends Armor 3

CASE

Stainless Steel 03/4" To 1" Thread Adapter 1

LOW PRESSUREEND CONNECTOR

HIGH PRESSUREEND CONNECTOR

Female (Probe or 0Driver mate)

Male (CMSS958 1ExtensionCable Mate)

No Connector 3

OTHER OPTIONS

+1: Use configuration illustrations and chart below to determine length/compatible system.

CABLE LENGTH +1

1.0 Meters (For CMSS 65 10and CMSS 68)



CABLE 1 HIGH PRESSUREEND LENGTH

CABLES 2 AND 3 HIGH PRESSURE END LENGTH

Increments Of 0.1 Meter XXMinimum: 0.2 MetersExample: 25 = 2.5 Meters

Cable Not Used 00

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When ordering, customers are requested to provide information to define the Eddy Probe System this item will be used with to facilitate calibration.

Ordering Information: (SKF Standard: CMSS 920-1000-100500-010)

Eddy Current Probe Installation Accessories 15

CMSS 911 Probe Holder/Dual Sensor Holder with Housing

3.50"(89mm)

4.75"(121mm)

3.00"(76mm)

5.87"(150mm)

Dimension "B"

Dimension "A"Penetration

Depth

Probe Tip(Reference Only)

Machine Shaft

Outside Surface of Machine

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10AAAA8

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7

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1

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5

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CMSS 911 Probe HolderThe CMSS 911 Probe Holderwith Housing offers anadjustable probe mount with avariety of penetration depths.The integral housing protects theprobe cable exit and permitseasy access for probe adjustmentwithout machine disassembly. Itis recommended that reversemount probes be used or thatstandard case probes be orderedwith a case length of 1.2 inchesand an overall cable length of0.5 or 1.0 meters. The housinghas four 3/4" NPT hubs forconduit attachment (3 close-upplugs provided).

1. Outlet Body (Part Number10699400) GRR-2

2. Outlet Body Extension (PartNumber 10699300)GRCEX-0

3. Outlet Body Hub, 3/4" NPT(4 Each)

4. Probe Adapter Union; 3/4"NPT (Part Number30180900)

5. Probe Adapter Collar (PartNumber 30187900)

6. Hex Head Steel Cap Screw(Part Number 10702200)

7. Probe Holder (“Stinger”)(Part Number – VariousDepending On ProbeHolder Length)

8. Jam Nut, Integral To ReverseMount Eddy Probe Case

9. “O” Ring Union Seal (PartNumber 10711803)

10. “O” Ring Tip Seal (PartNumber 10711800)

CMSS 911 Dual Sensor HolderThe CMSS 911 Dual SensorHolder with or without thehousing provides for themounting, adjustment andprotection of the eddy probe aswell as provides for mounting anaccelerometer or velocity sensoron the same axis as the eddyprobe for absolute vibrationmeasurements. It isrecommended that reversemount probes be used or thatstandard case probes be orderedwith a case length of 1.2 inchesand an overall cable length of0.5 or 1.0 meters. The housinghas four 3/4" NPT hubs forconduit attachment (3 close-upplugs provided).

1. Outlet Dome (Part Number10699402) 4GOU

2. Seismic Sensor MountingAdapter (Part Number301194200)

3. Outlet Body (Part Number10699401) GECXAT-2

4. End Plug (Part Number10746003) CUP-2

5. Probe Adapter Union (PartNumber 30180900)

6. “O” Ring Union Seal (PartNumber 10711803)

7. Jam Nut, Integral To ReverseMount Eddy Probe Case

8. Seismic SensorAccelerometer/Velocity

9. Probe Adapter Collar (PartNumber 30187900)

10. Hex Head Steel Cap Screw(Part Number 10702200)

11. Probe Holder (“Stinger”)(Part Number – VariousDepending On Length)

12. “O” Ring Tip Seal (PartNumber 10711800)

3.88"(99mm)

5.50"(140mm)

8.50"(216mm)

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AA1

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AA4

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5

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AA7

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9

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AA11

AA12

Intermediate Support/Oil Seal

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Intermediate support/oil seal. Recommended for use with probeholders 8 inches (203 mm) or longer in length. Provides supportand aids in eliminating/minimizing probe holder resonancescausing inaccurate probe measurements. For use with probeholders with model numbers CMSS 911-0XX-XXX only.

Part Number 31194401 (1" – 12 threads).

Part Number 31194400 (3/4" NPT threads).

Probe Adapter

Part Number 30221900Probe Adapter 3/8–24 to1/4–28 used wheninstalling CMSS 61 andCMSS 65 Probes in ProbeHolder with 3/8–24threads.

CMSS 61 and CMSS 65Probe Tip Assembly(Reference only)

†1A Dimension A penetration depth will be 1.0 inches less than indicated.

†1B Dimension A penetration depth will be 2.0 inches less than indicated.

†1C Dimension A penetration depth will be 3.0 inches less than indicated.

†1D Dimension A penetration depth will be 6.5 inches less than indicated.

†2 Indicated depth is center of ± 0.7" adjustment range for standard CMSS 911 units. Indicated depth is ± 0.5" adjustment range for dual sensorunits. API 670 recommends maximum of 8 inches of free cantilevered length. Use intermediate support/oil seal for longer lengths.

†3 Center of adjustment depth may be field cut within the indicated range.

†4 Probe Adapter 1/4–28 to 3/8–24 threads, Part Number 30221900 is required and must be ordered separately when using CMSS 65/CMSS 61standard Eddy Current Probes with the larger diameter stringers.

†5 This option does not require removal of connector of probe cable during field assembly. CMSS 65/CMSS 68 3/8–24 Reverse Mount Eddy Probeis recommended configuration offered in either 5mm or 8mm versions.

†6 This option size stinger only available in the standard 020 and 050 lengths.

†7 This option provides "Stingers" with M10 X 1 probe threads and can be used with CMSS 65 and CMSS 68 Reverse Mount Probes with M10 X 1thread cases.

†8 Eddy Probe connector must be removed and reinstalled when using this size threaded stinger.


CMSS 911 Probe Holder/Dual Sensor Holder with Housing


PROBE THREAD †4

DIMENSION BADAPTER LENGTH

OTHER OPTIONS

3/8–24 CMSS 65/CMSS 68 0Reverse Mount Standard †5

1/4–28 CMSS 65 Standard †6, †8 1M10 X 1 CMSS 65 and CMSS 68 2

Reverse Mount With M10 X 1Case †7

0.5 Inch (Standard) 01.5 Inches †1A 32.5 Inches †1B 13.5 Inches †1C 27.0 Inches †1D 4

None Required 0Probe Holder WITHOUT Housing 1Dual Sensor WITH Housing 6Dual Sensor WITHOUT Housing 7

CMSS 911

DIMENSION APENETRATION DEPTH †2

Standard Lengths: †3 020Short (1.0" To 2.0")Long (2.0" To 5.0")

Non-Standard Lengths: †26 Inches 0607 Inches 0708 Inches 0809 Inches 09010 Inches 10011 Inches 11012 Inches 12013 Inches 13014 Inches 14015 Inches 15016 Inches 16017 Inches 170

– NOTE –

Customers are strongly encouraged to use the

CMSS 65/CMSS 68 Reverse Mount Eddy Probe

Options when mounting Probes in CMSS 911

Holders.

– NOTE –

With the ± 0.07" adjustment these length

stingers should meet all length requirements

without trimming or cutting to interim custom

lengths (i.e. 9.3", 10.7", etc.).

PROBE THREAD

OTHER OPTIONS

3/8–24 CMSS 65/CMSS 68 0Reverse MountStandard †1

None Required 0

DIMENSION "A""STINGER" DEPTH

Short (0.75" To 2.50") * 025Long (1.45" To 5.50") * 055

CMSS 904


CMSS 904 Probe Holder

0.50" NPT External(Machine Case

Mounting Point)

0.50" NPT Internal(Conduit Mount)

Adjustment Range

Dimension "A"

By trimming stinger, working range of long CMSS 904 is 4.00" to 7.75" frommounting surface to probe tip (combination of stinger length and adjustment insidethreaded stock); range of short CMSS 904 is 2.50" to 4.75".

The CMSS 904 Probe Holderprovides a rigid mount withprovision for external gapadjustment. Conduit may be readilymounted at the cable exit. TheCMSS 904 provides 0.75" ofadjustment range after installation; aset screw securely locks theadjustment. It is recommended thatprobes be ordered with a case lengthof 1.2 inches or use the standardreverse mount probe.


†1 CMSS 65/CMSS 68 3/8–24 ReverseMount Eddy Probe is recommendedconfiguration offered in either 5mm or8mm versions.

* “Stingers” may be cut down in the fieldwithin the indicated ranges.

4.62" (116mm)

6.62"(166mm)

Machine Surface

1/2" NPT (2 Places)

Probe (2) Not Included

1.5"(38mm)

Shaft

WorkingRange

Fitting Not Furnished

Conduit Hub 3/4"

CMSS 912 Dual Axial Probe Adapter

The CMSS 912 Dual Axial Probe Adapterprovides mounting and protection for twoparallel probes for measuring axial thrustposition. The probes are mounted on adapterswhich are installed directly on the machinecase through 1/2-inch NPT-threaded holes.The adapters provide for easy gapping of theprobes. The enclosure bolts directly to themachine case and protects the probeinstallation. A removable cover providesaccess to the installed probe.

It is recommended that probes be ordered witha case length of 1.2 inches and an overalllength of 0.5 or 1.0 meters.

MODEL WORKINGNUMBER RANGE* PROBE THREAD

CMSS 912-1 1.10" To 2.35" 1/4–28 CMSS 65 StandardCMSS 912-2 1.30" To 5.35" 1/4–28 CMSS 65 StandardCMSS 912-3 0.75" To 2.00" 3/8–24 CMSS 68 StandardCMSS 912-4 0.95" To 5.00" 3/8–24 CMSS 68 Standard

* Working range with field trim of probe holder.

CMSS 903-1 CMSS 903-2 CMSS 903-3

Mounts CMSS 68 Series Probes (3/8–24 Case) Mounts CMSS 65 Series Probes (1/4–28 Case) Mounts CMSS 65 Series Probes (1/4–28 Case)

0.88"(22mm)

0.75"(19mm)

0.50"(13mm)

1.25"(31mm)

0.625"(16mm)

0.20" (5mm)

0.30"(8mm)

0.25"(6mm)

0.88"(22mm)

0.88"(22mm)

0.75" (19mm)

0.50"(13mm)

1.25"(31mm)

Sleeve


Mounting Devices, Adapters, and Packing Glands

The basic design and construction ofthe SKF Condition Monitoring EddyProbes insures long, dependableservice life. However, properinstallation is essential; once adjustedto its optimum position, a probe mustbe absolutely immovable.

Standardized installation devices areoffered for this specific purpose. Theyeliminate the chore of making specialbrackets or fixtures for eachinstallation. They also help insure thatevery SKF Eddy Probe will continue todeliver all the accuracy built into it …year after year.

(From left to right) CMSS 903 Series Probe Adapters: CMSS 903-1 Probe Holder; CMSS903-3 Probe Holder; CMSS 903-2 Probe Holder.

CMSS 903 Mounting Brackets areused in those installations requiringprobe mounting in the machine’sinternal area.

CMSS 903-1 Probe Holders are usedto install CMSS 68 Series Eddy Probeson flat machine surfaces. Threaded(3/8–24) and slotted, they insure a firmgrip on the probe, once it is adjusted tofinal operating position. Twomounting holes accommodate #10 hightensile Allen head cap screws (notprovided) which are normally securedwith safety wires.

Material: Anodized aluminum.

CMSS 903-2 Probe Holders are usedfor installing CMSS 65 Series EddyProbes on flat machine surfaces whenspace is at a premium. They arethreaded (1/4-28) and slotted to insurea firm grip after final adjustment.Mounting holes accommodate two #6high tensile Allen head cap screwswith safety wire holes (not provided).

Material: Stainless Steel.

CMSS 903-3 Probe Holders aresimilar to the CMSS 903-1 but aredesigned to hold CMSS 65 SeriesEddy Probes and, in addition, permitfinal adjustment where it is not

possible to turn the Probe itself. Thisis especially convenient for installationof Probes with armored or otherwiseprotected leads.

The Probe is threaded into a sleeve,which mates with a left-hand thread inthe main body of the Holder. Turningthe sleeve then sets the Probe position;it is not necessary to turn the Probeitself. Both Holder and sleeve areslotted to insure a firm grip on theProbe. Mounting holes accommodatetwo #10 high tensile Allen head capscrews with safety wire holes (notprovided).

Material: Anodized aluminum.

CMSS 903 Series Mounting Brackets

1.70"(43.5mm)

2.50" (63.5mm)

1/2" NPTInternal Thread

For ConduitInstallation

1.375" HEX 35

1/2" NPTor 3/4" NPT

Neoprene Packing

0.12" Diameter

Set Screw

1.20"(30.5mm)

Teflon Washers

Split Washers Split Washers


CMSS 30112000 Series Cable Packing Gland Assembly

The CMSS30112000 SeriesCable PackingGland Assemblyoffers a splash-proof cable exitfrom the machinecase. They areavailable in 1 or 2cable exit versionsand with either a1/2" or3/4" NPT male thread for screwinginto the machine housing. It is aneffective and easily installed lowpressure (60 psi/4 bars) seal. Theinternal oil resistant neoprene packingas well as washers are split to allowcable installation without connectorremoval.

The Cable Packing Glands aretypically used for exiting the EddyProbe Cable or Extension Cable forinternally installed Eddy Probes.

The Cable Packing Gland will notprovide a seal for armored cables.

Ordering InformationCMSS 30112000

One (1) cable exit, 1/2" NPTthread

CMSS 30112001Two (2) cable exit, 1/2" NPTthread

CMSS 30112003One (1) cable exit, 3/4" NPTthread

CMSS 30112004Two (2) cable exit, 3/4" NPTthread

CMSS 30112006 †1Two (2) cable exit, 1/2" NPTthread

CMSS 30112007 †1Two (2) cable exit, 3/4" NPTthread

†1 The CMSS 30112006 and CMSS30112007 models have split washerswhich can accommodate an Eddy ProbeCable and an Accelerometer/VelocityTransducer Cable for internal installationsof absolute Vibration Transducers.

CMSS 30837800 1/2" or 3/4" NPT Probe Adapter

1/2" NPTor 3/4" NPT

1/4–28 Thread or3/8–24 Thread

The Probe Adapter is used to mount a probe with a 1/4–28 or3/8–24 thread in a machine case which will accept the 1/2" or3/4" NPT fitting. Conduit or a junction box may be mounted onthe exterior side of the adapter.

Ordering InformationCMSS 30837800

3/8–24 internal thread for CMSS 68 style probes. 1/2" NPTexternal thread.

CMSS 308378011/4–28 internal thread for CMSS 65 style probes. 1/2" NPT

external thread.


external thread.


external thread.

20 Driver Housings

Explosion-Proof Housings For DIN-Rail Mount Drivers

Explosion-ProofHousingsExplosion-Proof and Dust-TightHousings

Class I, Group C and D

Class II, Groups E, F, and G

Class III,

UL Standard 886

CSA Standard C22.2,Number 30 1970

The Explosion-Proof housing isdesigned for use in environmentsclassified as hazardous. The housingis manufactured of aluminum alloywith a copper content less than 0.3%maximum. On three sides the bossesare drilled and tapped for 3/4" NPTconduit fittings. The dome typehousing is specified requiring aminimum of floor space for fixturemounting.

7.8750"(20.0cm)

6.3750"(16.2cm)

6.3750"(16.2cm)

7.8750"(20.0cm)

0.4375"Diameter

Hole

"B""A"

Ordering InformationExplosion-Proof Housings for RYTON™ DIN-Rail Mount Drivers. The units comewith all hardware ready for assembly and installing the drivers.

CMSS 31091700 Explosion-Proof Housing for maximum four drivers

"A" "B" Diameter Mounting WeightCatalog Number Inside Overall Cover Hole Each

Dome Height Opening Size Pounds

CMSS 31091700 10.2500" 11.4375" 6.8750" 0.4375" 15(26.0cm) (29.0cm) 17.5cm) (6.5 kg)

– NOTE –

Please refer to reference information in the back of this catalog for definitions, standards

and cross references.

Driver Housings 21

Weatherproof Housings

Weatherproof Housing(NEMA 4 and 4X)Meets requirements for NEMA Type4, Type 4X, Type 12 and Type 13.

UL 508 Type 4 and Type 4X

CSA Type 4.

IEC 529, IP66 (European Standard)

Weatherproof HousingsFor Protection FromAdverse EnvironmentalConditionsSKF Condition Monitoring productline offers three types of housings toprovide protection from adverseenvironmental conditions for DIN-RailMountable Eddy Probe Drivers.

Water-Resistant HousingEnclosures are intended for indoor oroutdoor use primarily to provide adegree of protection against corrosion,windblown dust and rain, splashingwater, and hose-directed water;undamaged by the formation of ice onthe enclosure. The housings areconstructed of 14 or 16 gauge steelwith seams continuously welded.Holes and cable clamp fittings areprovided. The cover is held in placeby steel clamps on four sides of coverto assure water tight integrity. There isan oil-resistant gasket held in placewith oil resistant adhesive. Finish isANSI 61 gray polyester powdercoating. Meets NEMA 4 criteria.

Water and CorrosionResistant Housing(Stainless Steel)Meets the same criteria as the WaterResistant Housing in addition to beingmanufactured of stainless steel to meetthe CORROSION RESISTANTcriteria. Finish is unpainted polishedsurface. Meets NEMA 4X criteria.

OrderingInformationWeatherproof housingsfor RYTON™ DIN-Railmount Drivers.

Area Classification— (Clamp Cover)

NEMA/EEMACType 4, Type 12 andType 13

UL50 Type 4, Type12, Type 13

UL508 Type 4, Type12, Type 13

CSA Type 4

IEC 529, IP66

CMSS 31092100 †1Weatherproof Housing formaximum three Drivers

CMSS 31092200 †1Weatherproof Housing formaximum six Drivers

CMSS 31092300 †1Weatherproof Housing formaximum ten Drivers

Area Classification —(Stainless Steel, ClampCover)

NEMA/EEMAC Type 4, Type4X, Type 12 and Type 13

UL50 Type 4, Type 4X


CSA Type 4, Type 4X

IEC 529, IP66




Area Classification —(Stainless Steel) ContinuousHinge on one side, Clampson other three sides of cover.

NEMA/EEMAC Type 4, Type4X, Type 12 and Type 13



CSA Type 4, Type 4X

IEC 529, IP66




– NOTE –

Please refer to reference information in theback of this catalog for definitions, standards

and cross references.

†1 If it is desired to order a housing with "NOHOLES" then add a "–NH" to the right ofthe model number, i.e. CMSS 31092100–NH.

SKF Box Size Mounting Clamp Style Overall Hinge Style OverallModel Number "A" x "B" x "C" "D" x "E" "L" x "W" "L" x "W"

CMSS 31092100 8.00" x 6.00" x 3.50" 8.75" x 4.00" 9.50" x 7.38" 9.50" x 6.94"CMSS 31092101 (203mm x 152mm x 89mm) (222mm x 102mm) (241mm x 187mm) (241mm x 176mm)CMSS 31092103

CMSS 31092200 10.00" x 8.00" x 4.00" 10.75" x 6.00" 11.50" x 9.38" 11.50" x 8.94"CMSS 31092201 (254mm x 203mm x 102mm) (273mm x 152mm) (292mm x 238mm) (292mm x 227mm)CMSS 31092203

CMSS 31092300 12.00" x 10.00" x 5.00" 12.75" x 8.00" 13.50" x 11.38" 13.50" x 10.94"CMSS 31092301 (305mm x 254mm x 127mm) (324mm x 203 mm) (343mm x 289mm) (343mm x 278mm)CMSS 31092303

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

12 Gauge

1.25" (32mm)

L

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AAAAAAAAAAAAAAAAAAAAAAAA

B

W

C

DAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

EB

A

0.75" (19mm)

∅0.31"Diameter(8mm)

0.75" (19mm)

AAAAAAAAAAAAAA

B

W

C

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

12 Gauge

1.31" (33mm)

L


– NOTE –

Due to changes in housing manufacturer

specifications, cover clamps may be located in

positions other than depicted in these

drawings.

22 Driver Housings

Weatherproof Housings For DIN-Rail Mount Drivers

Weatherproof Housing Dimensions

Clamp Style

Hinge Style

The CMSS 601-1 is supplied as a portable kit complete withstandard target disc, an Allen wrench and two adapters toaccommodate both CMSS 65 and CMSS 68 Eddy Probes.

CMSS 601 Static Calibrator 23

CMSS 601 Static Calibrator

The CMSS 601 Field Calibratorprovides a convenient, precise methodfor verifying the voltage output vs. gapof an Eddy Probe and Drivercombination. It is especially useful forapplications requiring exact calibration(the hot alignment of machinery) orwhere “targets” of various metal alloysare used.

As recommended by API Standard670, the CMSS 601 can be used forcalibrating an Eddy Probe on the actualshaft it will monitor. The Calibrator’sself-centering magnetic base holds thepickup rigidly at 90° to the shaft axisto provide reliable performancecharacteristics on its “real target.” Themetal disc supplied with the Calibratormay be placed across the V-Shapedbase as a standardized flat calibrationtarget.

Precision Results …Easy to Use1. An Eddy Probe is locked into the

proper size adapter with the setscrew.

2. The adapter and probe cable areslipped upward through themagnetic base and over themicrometer spindle.

3. The magnetic base is placed on amachine shaft or on the target disc.

4. The probe lead is connected to amatching Eddy Probe Driverthrough an Extension Cable.

5. -24 Vdc is applied to the driver,whose output is connected to avoltmeter.

6. The micrometer spindle is set toread 40 mils.

7. The adapter and probe are verticallypositioned to produce a -8 Vdcvoltmeter reading and then lockedin position on the micrometerspindle by the upper set screw. Theunit is now ready for use.

To calibrate an Eddy Probe, thespindle is lowered by the micrometerhead to a reading of 10 mils and avoltage reading taken. Readings aretaken successively at 5 mil or 10 milincrements. Fine tuning is availablewith the calibrate potentiometer on thedriver.

Ordering InformationCMSS 601-1 Standard (English units)

CMSS 601-2 Metric Version (Metricunits)

CMSS 601-7 For long probe cases(over 2.0")* (English units)

CMSS 601-8 Metric Version for longprobe cases (over 60mm)* (Metricunits)

* Calibrators for long probes use integraltarget only … will not observe actual shaft.

24 CMSS 748-3 Probe Gapper

Fast, Easy, Accurate . . .To save time and money in the field, SKF ConditionMonitoring offers a unique device — The CMSS 748-3Probe Gapper, a portable, battery-powered unit for theSKF CMSS 65, and CMSS 68 Eddy Probes.

Whether you are on the factory floor, in a test cell orworking on a machine in the plant, you can use theCMSS 748-3 for conveniently gapping a probe at 40mils direct reading. (No conversion from volts isnecessary as with a voltmeter.) Built-in signalconditioning allows a probe to be gapped with orwithout the extension cable, and there is never any needto wait for conduit runs and wiring to be installed backto the drivers and monitors.

Since the CMSS 748-3 stays “on” for a period of 4-5minutes after the Power-On switch is pressed, theoperator can use two hands to set and lock the probe inplace.

SpecificationsProbe WITHOUT CMSS 958 Compatibility: CMSS 65 or

CMSS 68 with 1 meter cable overall length.

Probe WITH CMSS 958 Compatibility: Any Probe andExtension Cable combination normally driven by astandard 5 meter CMSS 665 or CMSS 668 Series driver.

Dimensions: 2.4" (52mm) Height x 3.6" (103mm) Width x9.3" (236mm) Length

Weight: 1.6 lb. (0.62 Kg)

Batteries: Four each 9V Transistor.

Life approximate: 10 – 12 hours continuous use.

– NOTE –

40 mil reading only accurate with SKF CMSS 65 or CMSS 68 Eddy

Current Probes observing 4140 steel or a similar metal.

CMSS 748-3 Probe Gapper

Ordering InformationCMSS 748-3 Standard for use with CMSS 65 or CMSS 68

Eddy Probes only.

Typical Eddy Probe Arrangement Plans 25

Typical Eddy Probe Arrangement Plans

TurbineItem Description

P1 Axial position probe (instrument manufacturer IDdata).

P2 Axial position probe (instrument manufacturer IDdata).

3Y Low pressure end radial vibration probe, 45° off TDC(instrument manufacturer ID data).

4X Low pressure end radial vibration probe, 45° off TDC(instrument manufacturer ID data).

5Y High pressure end radial vibration probe, 45° off TDC(instrument manufacturer ID data).

6X High pressure end radial vibration probe, 45° off TDC(instrument manufacturer ID data).

Ø Phase reference probe, 45° off TDC (instrumentmanufacturer ID data).

R Radial bearing (description)

T Thrust bearing (description)

JB Junction box

NOTES: 1. The numbering system shown is based on the higher pressureend equaling a higher device number.

2. TDC = Top dead center.

Item Description

P1 Axial position probe (vendor and model number).

P2 Axial position probe (vendor and model number).

3Y Low pressure end radial vibration probe, 45° off TDC(vendor and model number).

4X Low pressure end radial vibration probe, 45° off TDC(vendor and model number).

5Y High pressure end radial vibration probe, 45° off TDC(vendor and model number).

6X High pressure end radial vibration probe, 45° off TDC(vendor and model number).

Ø Phase reference probe, 45° right of TDC (vendor andmodel number).



JB Junction box (description)

NOTES: 1. TDC = Top dead center.

Compressor

26 Typical Eddy Probe Arrangement Plans


Electric MotorItem Description

3Y Coupling end Y radial vibration probe, 45° off TDC(instrument manufacturer ID data).

4X Coupling end X radial vibration probe, 45° off TDC(instrument manufacturer ID data).

5Y Outboard end Y radial vibration probe, 45° off TDC(instrument manufacturer ID data).

6X Outboard end X radial vibration probe, 45° off TDC(instrument manufacturer ID data).

Ø Phase reference probe, 45° off TDC (instrumentmanufacturer ID data).

T1 Outboard end bearing temperature.

T2 Coupling end bearing temperature.


JB Junction box


PumpItem Description

A1 Coupling end radial horizontal accelerometer, 90° offTDC (instrument manufacturer ID data).

A2 Outboard end radial horizontal accelerometer, 90° offTDC (instrument manufacturer ID data).



JB Junction box


Typical Eddy Probe Arrangement Plans 27


Gear Box (Double Helical Gear)

Item Description

3Y Input shaft coupling end Y radial vibration probe, 45°off TDC (instrument manufacturer ID data).

4X Input shaft coupling end X radial vibration probe, 45°off TDC (instrument manufacturer ID data).

A1 Input shaft coupling end horizontal radial acceleration,90° off TDC (instrument manufacturer ID data).

P1 Input shaft thrust bearing end axial position probe #1,(instrument manufacturer ID data).

A2 Output shaft coupling end horizontal radialacceleration, 90° off TDC (instrument manufacturerID data).

5Y Output shaft coupling end Y radial vibration probe,45° off TDC (instrument manufacturer ID data).

6X Output shaft coupling end X radial vibration probe,45° off TDC (instrument manufacturer ID data).

Ø1 Input shaft noncoupling end phase reference probe atTDC (instrument manufacturer ID data).

Ø2 Output shaft noncoupling end phase reference probe atTDC (instrument manufacturer ID data).

P2 Output shaft thrust bearing end axial position probe #2(instrument manufacturer ID data).



JB Junction box


2. Oscillator-demodulators and accelerometer signalconditioners should be located in separate junction boxes.

3. For a single helical gear, a pair of axial probes should beinstalled at each thrust bearing end.

1/2" Flex Conduit "Sealtite"Or Equivalent (Typical) 3/4"–1/2" Reduction

Bushing (Typical)

CMSS 911 Extension(Use As Required)

Rotation

1 2

4 6

3 Typical

8

7

Side View

CMSS 911 Assembly (Typical)

Thermocouple Wire

Radial Bearing Thrust Collar Thrust Bearing

7

4

6

1

3

28

28 Bearing Housing Mounting

Bearing Housing Mounting

End View

Notes:

1 Drill and tap housing for 3/4"NPT (typical).

2 Set sealing adapter tight inbearing housing before pullinglead wires.

3 Identify leads prior toinstallation. Use tag numbers asrequired.

4 Probes must be mountedperpendicular to shaft.

5 Do not pull thermocouple wireand probe lead wires into sameoutlet without EngineeringDepartment approval.

6 Check gap Volts after CMSS911 assembly has been installed.Set gap at -8.0" ± 1/2 Volts (40± 2.5 mils). May use SKFCondition Monitoring CMSS748 Probe Gapper.

7 Torque mating connectors to 145± 5 inch-ounces. Then wrapconnections with Teflon tape(typical).

8 Drill 1/4" drain hole in lowestpoint of box (typical).

Axial Probe Installation 29

Axial Probe Installation

5 Do not pull thermocouplewires and probe lead wires intosame outlet withoutengineering departmentapproval.

6 Check gap volts afterCMSS 911 or CMSS 912assemblies have been installed.Use CMSS 748 Probe Gapperor digital voltmeter.

7 Set gap at midpoint of proberange at the center of the shaftfloat zone.

8 Torque mating connectors to145 ± 5 inch-ounces. Thenwrap connectors with Teflontape.

Thrust Probe InstallationRecommendations

1. At least two probes per rotor arerecommended.

2. Where the probes cannot bechanged without shutting down themachine, install spare probes.

3. Calibrate probe, cable and driverand record final response curves forprimary as well as spare probes.The SKF Condition MonitoringCMSS 601 Static Calibrator may beused.

4. Try to observe the thrust collar withone probe and the shaft with theother.

5. Probes must be mounted with in onefoot of the thrust collar.

6. Avoid mounting probes through thinplates or bell housings that may bowwith thermal expansion.

7. Determine the float zone of the rotorby jacking the rotor in bothdirections. Use up to 2 tonspressure.

8. Measure the rotor movement withdual indicators on the shaft, theEddy Probe voltage change at thedriver and the monitor reading. (Allthree should agree.)

9. Jack the shaft several times eachway to verify readings.

10. Set the probe gap so that the centerof the probe’s range is in the centerof the float zone.

11. Securely lock the probe and anyadapters in place.

12. Be sure the probe tip has a sideclearance of at least 0.200".

Notes:

1 Set sealing adapter tight inhousing before pulling leadwires through.

2 Probe lead wires must besecured against internalwhipping and rubbing.

3 Identify probe leads prior toinstallation. Use tag numbersas required.

4 Probes must be mountedperpendicular to shaft orsurface it is “seeing”.

CMSS 912 Dual Thrust Assembly

1/2" Conduit Hub

3

BellHousing

1/2" Conduit Hub

3 (Typical)

BellHousing Use Locktite On Threads

16

Working Range RecommendedMinimumThickness Is 3/8"

Surface Must Be FreeOf Stencil Marks andOther Discontinuities

6.62"(168mm)

4.62"(117mm)

Axial Probe

Axial Probe

Key Phasor Probe

2

30 Outline Dimension Drawings

5mm and 8mm Eddy Probe Outline Dimension Drawing

50.00" MAX33.00" MIN

6 8mm (0.312") for CMSS 68.5mm (0.200") for CMSS 65.

7 1/4–28 or 3/8–24 according to probe model number.

8 All information applies to both models unlessotherwise specified.

9 Armored model only.

10 All dimensions in parentheses are millimeters (mm).

1 Cable shown with and without flex armor.

2 Drawing applicable to CMSS 65 and CMSS 68.

3 Clear shrink tubing for label identification.

4 7/16" for 1/4–28 thread probe case. (13mm for M8 x1 thread probe case.)

9/16" for 3/8–24 thread probe case. (17mm for M10 x1 thread probe case.)

5 Probe case length dependent on probe model number.

4.0 meters – nominal 160.00"3.6 meters – minimum 140.00"

AAAAAAAAAAAAAAAA

1 2 3 4 5AAAAAAA

3.00"(7.62cm)



AAAAAAAAAAAAAAAAAAAAAAAAA

AAAAAAAAA

-24V

GN

DS

IGG

ND

-24V

AAAAAAAAAAAAAAAA

AAAA

AA

AAAA

AA

CMSS 668

AAAAAAAA

2.50"(6.35cm)

3.00"(7.62cm)

2.50"(6.35cm)

4 X ∅ 0.25" Clearance Hole For Mounting With 10-32 Hardware, Machine Screws 1.375" Minimum Length

5 4

A1.00"

(2.54cm)

REMOVABLE OR PERMANENT FIXED CONNECTOR:Terminal Strip Type Rated For 250 V, 10 AMPS 14 AWG. Maximum Wire Size

Removable Neoprene Plug

1.60"(4.06cm)

A

0.60"(1.52cm)

AA

AAAAAAAAA "C" DIN-Rail

Mount

"C" DIN-Rail

1.95"(4.95cm)

1.10"(2.79cm)

3.90"(9.91cm)

This outline drawing applies to the following drivers:

CMSS 665 and CMSS 665P SeriesCMSS 668 and CMSS 668P Series

3 Units interchangeable without recalibration.

4 Probe driver 5 terminal connector shown.Removable or permanent fixed connectors available.

5 Access hole for fine trimming of calibration on probedrivers or for range selection on transmitter units.

Outline Dimension Drawings 31

5mm and 8mm Eddy Probe Driver Outline DimensionDrawing

1 Specifications:Operating Temperature Range: -30°F to +150°F(-35°C to +65°C)

2 Storage: -45°F to +150°F (-43°C to +65°C)Material: Case made from RYTON®

5 High strength steel coax with steel braid shield.

6 Installation direction not restricted (Reversible).

7 Information applies to both models unless otherwisespecified.

8 Armored model only.

9 All dimensions in parentheses are millimeters (mm).

32 Outline Dimension Drawings

CMSS 958 Extension Cable Outline Dimension Drawing

1 Cable shown with and without flex armor.

2 Clear shrink tubing for label identification.

3 Specifications:Operating Temperature Range: -30°F to +250°F(-35°C to +120°C)

Storage: -45°F to +250°F (-43°C to +120°C)

4 Bend radius 1.375" (34.9mm) minimum (Armored).Bend radius 0.750" (19.0mm) minimum (Non-Armored).

Hazardous Area Information 33

CE MarkEuropean Community Declaration ofConformity.

Manufacturer:

SKF Condition Monitoring

4141 Ruffin Road

San Diego, California USA

Product: SKF Eddy Current ProbeSystems

SKF Condition Monitoring, Inc. ofSan Diego, California USA herebydeclares, that the referenced product,to which this declaration relates, is inconformity with the provisions of:

Council Directive 89/336/EEC (3May 1989), on the Approximationof the Laws of the Member StatesRelating to ElectromagneticCompatibility, as amended by:

Council Directive 92/31/EEC(28 April 1992);

Council Directive 93/68/EEC(22 July 1993).

The above-referenced productcomplies with the following standardsand/or normative documents:

EN 50081-2, Electromagneticcompatibility–Generic emissionstandard. Part 2: Industrialenvironment (August 1993).

EN 50082-2, Electromagneticcompatibility–Generic immunitystandard. Part 2: Industrial

Hazardous Area Information

Area GeneralInformationReview the Hazardous LocationInformation section to properly definethe area in which the sensors andmonitoring systems are to be installed,then determine which equipment willmeet the specified requirements.

Sensors may either be installed in aClass 1, Division 1 (Zone 0, 1) or aDivision 2 (Zone 2) hazardous area.However, for installation in theseareas, the sensors must be approved byan appropriate agency.

SKF Condition Monitoring does haveeddy probe sensor systems approvedfor installation in these areas andspecific model numbers assigned toeasily identify these agency approvedoptions.

It is strongly recommended thatintrinsic safety barriers be used for thehazardous area installations as themeans of limiting the thermal andelectrical energy to the sensorcomponents in Class 1, Division 1(Zone 0, 1) and Division 2 (Zone 2)hazardous areas. The agency approvedintrinsic safe sensor components, andthe intrinsic safety barriers provide fora very high level of safety, and aid inthe prevention of fire and explosions inyour facility.

It is recommended in fieldinstallations, that housings be used toprovide physical protection for theSKF Condition Monitoring EddyProbe Drivers. For CENELECapproved systems, these housingshould have a minimum rating of IP20.Other agency approvals do not specifya level of protection for the housings.

However SKF does provide a series ofstandard housings which can be usedfor these installations.

Agency ApprovalsSKF Condition Monitoring hasobtained agency approvals from thefollowing:

British Approvals Service forElectrical Equipment inFlammable Atmospheres –EECS (BASEEFA)

EECS (BASEEFA) intrinsically safecertified equipment is intended for usein Zone 0, 1 as intrinsically safe inaccordance with CENELEC Europeanharmonized Standards, [EN50 014(1977) and EN50 020 (1977)] and isaccepted by member countries ofAustria, Belgium, Denmark, Finland,France, Germany, Greece, Ireland,Italy, Luxembourg, the Netherlands,Norway, Portugal, Spain, Sweden,Switzerland, and the United Kingdom.

Canadian StandardsAssociation – CSA

CSA intrinsically safe certifiedequipment is intended for use in Class1, Division 1, Groups A, B, C, D.

Factory Mutual Research,USA – FM

FM intrinsically safe and non-incendive certified equipment isintended for use in Class 1, Division 1and Division 2, Groups A, B, C, D.

To order eddy probe systems withthe various agency approvals pleaserefer to the front part of the catalogunder the specific eddy probe modelnumber desired i.e. CMSS 65 orCMSS 68 systems. There is an optionsform available which delineates thespecific agency approval desired.Select the appropriate agency approvaland the additional configurationrequirements for the eddy probe andextension cable. Then select theappropriate driver model numberindicated on the pages following.

ApprovedFM

34 Hazardous Area Information

Intrinsic Safety (I-S) Barriers for Use With CMSS 65 andCMSS 68 Series Eddy Probe Systems

Canadian StandardsAssociation – CSA

Intrinsically safe for Class 1, Division1, Groups A, B, C, D

System Approval:

Barriers:

Power: Stahl 8901/30-280/085/00

Signal: Stahl 8901/30-199/038/00

Barriers are approved by FM, CSA,and PTB, CESI (CENELEC Standard)

SKF Condition Monitoring drawingnumber 31163300 is applicable

Power/Signal: MTL 796 Dual(neg)

Measurement Technology Ltd., (MTL)

SKF Condition Monitoring drawingnumber 31163200 is applicable.

– CAUTION –

All intrinsic safety installations should be done

in accordance with the national installation

codes of practice for the particular country at

the place of installation.

British Approvals Servicefor Electrical Equipment inFlammable Atmospheres –EECS (BASEEFA)(CENELEC Standard)

Intrinsic safe code (see below)

System Approval:

Intrinsic safe code EEx ia IIC T2


Eddy Probe Approval:

Intrinsic safe code EEx ia IIC T2(Tamb = +100°C)

Driver Approval:

Intrinsic safe code EEx ia IIC T4(Tamb = +75°C)

Umax:in = 28 Vdc,

Imax:in = 138 mAdc,

Wmax:in = 1.0 W

Ceq = 0.06 microfarad,

Leq = 0.5 millihenries

Suggested Barriers:

Power: Stahl 9003/50-200/050

Signal: Stahl 8901/34-280/000/60

Barriers are approved by EECS(BASEEFA) (CENELEC Standard).

Power/Signal: MTL796 Dual(neg)

Measurement Technology Ltd.,(MTL).

Barriers are approved by EECS(BASEEFA) (CENELEC Standard).

– CAUTION –

All intrinsic safety installations should be done

in accordance with the national installation

codes of practice for the particular country at

the place of installation.

The following information provides alisting of the Intrinsic Safety Barriersused by the various testing agenciesduring the eddy probe approvalprocess. As such these barriers meetthe various agency approvals and allowfor the proper operation of the SKFCondition Monitoring Eddy ProbeSystems when properly installed in thehazardous areas. Also included are theparameters for selecting othermanufacturers barriers.

However, only the brand namedbarriers listed have been tested and areverified to work properly with theCMSS 65 and CMSS 68 eddy probesystems.

Factory Mutual – (FM)

Intrinsically safe for Class 1, Division1, Groups A, B, C, D

Entity Parameters:

Supply terminals:

Vmax = 30 Vdc,Imax = 245 mA,Ci = 0.056 microfarad,Li = 0.536 millihenries.

Signal terminals:

Vmax = 24 Vdc,Imax = 60 mA,Ci = 0 microfarad,Li = 0 millihenries


System Approval:

Barriers:

Power: Stahl 8901/30-280/085/00

Signal: Stahl 8901/30-199/038/00

Barriers are approved by FM, CSA,and PTB, CESI (CENELEC Standard)


– CAUTION –

All intrinsic safety installations should be donein accordance with the national installation

codes of practice for the particular country atthe place of installation.

APPROVED

Hazardous Location Information 35

Classes and Divisions

Hazardous locations are those areaswhere a potential for explosion andfire exist because of flammable gases,vapors or finely pulverized dusts in theatmosphere, or because of the presenceof easily ignitable fibers or flyings.Hazardous locations may result fromthe normal processing of certainvolatile chemicals, gases, grains, etc.,or they may result from accidentalfailure of storage systems for thesematerials. It is also possible that ahazardous location may be createdwhen volatile solvents or fluids, usedin a normal maintenance routine,vaporize to form an explosiveatmosphere.

Regardless of the cause of a hazardouslocation, it is necessary that everyprecaution be taken to guard againstignition of the atmosphere. Certainlyno open flames would be permitted inthese locations, but what about othersources of ignition?

Electrical Sources ofIgnitionA source of ignition is simply theenergy required to touch off anexplosion in a hazardous locationatmosphere.

Electrical equipment such as lightingfixtures and motors are classified as“heat producing,” and they willbecome a source of ignition if theyreach a surface temperature whichexceeds the ignition temperature of theparticular gas, vapor or dust in theatmosphere.

It is also possible that an abnormalityor failure in an electrical system couldprovide a source of ignition. A loosetermination in a splice box or a looselamp in a socket can be the source ofboth arcing and heat. The failure ofinsulation from cuts, nicks or agingcan also act as an ignition source fromsparking, arcing and heat.

Hazardous Locationsand the NationalElectrical Code®*The National Electrical Code® treatsinstallations in hazardous locations inarticles 500 through 517.

Each hazardous location can beclassified by the definitions in theNEC. Following are interpretations ofthese classifications and applications.

CLASS I LOCATIONS

Class I locations are those in whichflammable gases or vapors are or maybe present in the air in quantitiessufficient to produce explosive orignitable mixtures.

Class I, Division 1

These are Class I locations where thehazardous atmosphere is expected tobe present during normal operations. Itmay be present continuously,intermittently, periodically or duringnormal repair or maintenanceoperations. Division 1 locations arealso those locations where abreakdown in the operation ofprocessing equipment results in therelease of hazardous vapors and thesimultaneous failure of electricalequipment.

Class I, Division 2

These are Class I locations in whichvolatile flammable liquids or gases arehandled, processed or used, but inwhich they will normally be confinedwithin closed containers or closedsystems from which they can escapeonly in the case of accidental ruptureor breakdown of the containers orsystems. The hazardous conditionswill occur only under abnormalconditions.

CLASS II LOCATIONS

Class II locations are those that arehazardous because of the presence ofcombustible dust.

* All references to the National ElectricCode® are from the NFPA 70 1990 Edition.

Class II, Division 1

These are Class II locations wherecombustible dust may be in suspensionin the air under normal conditions insufficient quantities to produceexplosive or ignitable mixtures. Thismay occur continuously, intermittentlyor periodically. Division 1 locationsalso exist where failure or malfunctionof machinery or equipment mightcause a hazardous location to existwhile providing a source of ignitionwith the simultaneous failure ofelectrical equipment. Included also arelocations in which combustible dust ofan electrically conductive nature maybe present.

Class II, Division 2

A Class II, Division 2 location is onein which combustible dust will notnormally be in suspension in the airand normal operations will not put thedust in suspension, but whereaccumulation of the dust may interferewith the safe dissipation of heat fromelectrical equipment or whereaccumulations near electricalequipment may be ignited by arcs,sparks or burning material from theequipment.

CLASS III LOCATIONS

Class III locations are those that arehazardous because of the presence ofeasily ignitable fibers or flyings, but inwhich the fibers or flying are not likelyto be in suspension in the air inquantities sufficient to produceignitable mixtures.

Class III, Division 1

These are locations in which easilyignitable fibers or materials producingcombustible flyings are handled,manufactured or used.

Class III, Division 2

These locations are where easilyignitable fibers are stored or handled.

36 Hazardous Location Information

Classes and Divisions

Hazardous LocationEquipmentCLASS I LOCATION EQUIPMENT

Devices for Class I locations arehoused in enclosures which aredesigned to be strong enough tocontain an explosion if the hazardousvapors enter the enclosure and areignited. These enclosures then cooland vent the products of combustion insuch a way that the surroundingatmosphere is not ignited.

Heat producing equipment forhazardous locations must also bedesigned to operate with surfacetemperatures below the ignitiontemperatures of the hazardousatmosphere.

Since the different vapors and gasesmaking up hazardous atmosphereshave varying properties, they havebeen placed in groups based oncommon flame propagationcharacteristics and explosionpressures. These groups aredesignated A, B, C, and D, and theequipment selected must be suitablefor the group of the specific hazardousgas or vapor, with regard to flamepropagation, explosion pressures andoperating temperatures.

Reference to the National ElectricalCode® will indicate that most of theequipment used for Class I Division 2applications is the same as that usedfor Division 1 applications.

CLASS II LOCATION EQUIPMENT

The enclosures used to house devicesin Class II locations are designed toseal out dust. Contact between thehazardous atmosphere and the sourceof ignition has been eliminated and noexplosion can occur within theenclosure.

As in Class I equipment, heatproducing equipment must be designedto operate below the ignitiontemperature of the hazardousatmosphere. However, in Class IIequipment, additional considerationmust be given to the heat buildupwhich may result from the layer of dustwhich will settle on the equipment.

Dusts have also been placed in Groupsdesignated E, F, and G, based on theirparticular hazardous characteristics andthe dusts’ electrical resistivity. It isimportant to select equipment suitablefor the specific hazardous group.

CLASS III LOCATIONEQUIPMENT

Class III locations require equipmentwhich is designed to prevent theentrance of fibers and flyings, preventthe escape of sparks or burningmaterial and operate at a temperaturebelow the point of combustion.

Hazardous LocationEquipment ApplicationsHazardous location equipment may berequired in any area where thepresence of flammable gases, vapors orfinely pulverized dusts in theatmosphere is sufficient to create athreat of explosion or fire. It may alsobe required where easily ignitablefibers or flyings are present. Thefollowing is a representative (buthardly complete) list of the types oflocations and operations requiringhazardous location equipment in atleast certain areas.

CLASS I LOCATIONS

• Petroleum refining facilities

• Dip tanks containing flammableor combustible liquids

• Dry cleaning plants

• Plants manufacturing organiccoatings

• Spray finishing areas (residuemust be considered)

• Petroleum dispensing areas

• Solvent extraction plants

• Plants manufacturing or usingpyroxylin (nitrocellulose) typeand other plastics (Class II also)

• Locations where inhalationanesthetics are used

• Utility gas plants, operationsinvolving storage and handlingof liquefied petroleum andnatural gas

• Aircraft hangers and fuelservicing areas

CLASS II LOCATIONS

• Grain elevators and bulkhandling facilities

• Manufacture and storage ofmagnesium

• Manufacture and storage ofstarch

• Fireworks manufacture andstorage

• Flour and feed mills

• Areas for packaging andhandling of pulverized sugarand cocoa

• Facilities for the manufacture ofmagnesium and aluminumpowder

• Some coal preparation plantsand coal handling facilities

• Spice grinding plants

• Confectionery manufacturingplants

CLASS III LOCATIONS

• Wood working plants

• Textile mills

• Cotton gins and cotton seedmills

• Flax producing plants

Hazardous Location Information 37

Chemical By Groups

Group A – Atmospheres• acetylene

Group B – Atmospheres• acrolein (inhibited)• butadiene• ethylene oxide• formaldehyde (gas)• hydrogen• manufactured gases containing

more than 30% hydrogen (byvolume)

• propylene oxide• propyl nitrate

Group C – Atmospheres• acetaldehyde• allyl alcohol• butyl mercaptan• n-butyraldehyde• carbon monoxide• crotonaldehyde• dicyclopentadiene• diethyl ether• diethylamine• di-isopropylamine• dimethylamine• 1, 4-dioxane• di-n-propylamine• epichlorohydrin• ethylene• ethylenimine• ethyl mercaptan• n-ethyl morpholine• hydrogen cyanide• hydrogen selenide• hydrogen sulfide• isobutyraldehyde• isopropyl glycidyl ether• methylacetylene• methylacetylene-propadiene

(stabilized)• methyl ether• methyl formal• methyl mercaptan• monomethyl hydrazine• morpholine• nitroethane• nitromethane• 2-nitropropane• propionaldehyde• n-propyl ether• tetrahydrofuran• triethylamine• unsymmetrical dimethyl

hydrazine (UDMH 1, 1-dimethylhydrazine)

• valeraldehyde

Group D – Atmospheres• acetic acid (glacial)• acetone• acetonitrile• acrylonitrile• allyl chloride• ammonia• n-amyl acetate• sec-amyl acetate• benzene• butane• 1-butanol (butyl alcohol)• 2-butanol(secondary butyl

alcohol)• n-butyl acetate• sec-butyl acetate• butylamine• butylene• chlorobenzene• chloroprene• cyclohexane• cyclohexene• cyclopropane• 1, 1-dichloroethane• 1, 2-dichloroethylene• 1, 3-dichloropropene• di-isobutylene• ethane• ethanol (ethyl alcohol)• ethyl acetate• ethyl acrylate (inhibited)• ethylamine• ethyl benzene• ethyl chloride• ethylenediamine (anhydrous)• ethylene dichloride• ethylene glycol monomethyl ether• ethyl formate• gasoline• heptane• heptene• hexane• 2-hexanone• hexenes• isoamyl acetate• isoamyl alcohol• isobutyl acrylate• isoprene• isopropyl acetate• isopropylamine• isopropyl ether• liquefied petroleum gas• mesityl oxide• methane (nature gas)• methanol (methyl alcohol)• methyl acetate• methyl acrylate• methylamine• methylcyclohexane• methyl ethyl ketone• methyl formate• methyl isobutyl ketone• methyl isocyanate• methyl methacrylate

Group D – Atmospheres• 2-methyl-1-propanol (isobutyl

alcohol)• 2-methyl-2-propanol (tertiary

butyl alcohol)• naphtha (petroleum)• nonane• nonene• octane• octene• pentane• 1-pentanol (amyl alcohol)• 2-pentanone• 1-pentene• petroleum naphtha• propane• 1-propanol (propyl alcohol)• 2-propanol (isopropyl alcohol)• n-propyl acetate• propylene• propylene dichloride• propylene oxide• pyridine• styrene• toluene• tripropylamine• turpentine• vinyl acetate• vinyl chloride• vinylidene chloride• xylenes

Group E – AtmospheresAtmospheres containing combustiblemetal dusts regardless of resistivity, orother combustible dusts of similarlyhazardous characteristics havingresistivity of less than 105 ohm-centimeter.

Group F – AtmospheresAtmospheres containing carbon black,charcoal, coal or coke dusts whichhave more than 8 percent total volatilematerial (carbon black per ASTMD1620; charcoal, coal and coke dustsper ASTM D271) or atmospherescontaining these dusts sensitized byother materials so that they present anexplosion hazard, and havingresistivity greater than 102 ohm-centimeter but equal to or less than 108ohm-centimeter.

Group G – AtmospheresAtmospheres containing combustibledusts having resistivity of 105 ohm-centimeter or greater.

38 Hazardous Location / Industry Reference Information

Hazardous Locations Cross Reference

Comparison of "Zones" to North America "Division" and the types of Protection Accepted

IEC North America

Zone 0 Intrinsically safe apparatus of category ia or other apparatus, both specifically approved for Zone 0.

Zone 1 All equipment certified for Zone 0

Apparatus with type(s) of protection.• "d" flameproof enclosure• "p" pressurized apparatus• "i" intrinsic safety (ia and ib)• "o" oil immersion• "e" increased safety• "q" powder filling• "s" special protection

In Future• "m" moulding

Zone 2 All equipment certified for Zone 0 or 1

Apparatus with type of protection:• "n" nonsparking/nonincendive

Class I, Some users recognize the Zone 0 principleDivision 1 without using the name and would only

install apparatus suitable for Zone 0 operation in such areas.

Apparatus with type(s) of protection:• explosion proof enclosures• purging• intrinsic safety• oil immersion

Class I, All equipment certified for Division 1Division 2

Apparatus incapable of creating sparks or hot surfaces capable of ignition in "general purpose" enclosures, ANSI/ISA-S12.12-1986*

* "Electrical Equipment for use in Class I, Division 2 Hazardous (Classified) Locations"

Industry Reference Information

What’s In A Rating?

As a way of standardizing enclosure performance,organizations like NEMA, UL, CSA, IEC, and TUVRheinland use rating systems to identify an enclosure’sability to repel the outside environment. Resistance toeverything from dripping liquid to hose down to totalsubmersion is defined by the ratings system.

While these ratings are all intended to provide information tohelp you make a safer, more informed product choice, thereare differences between them. NEMA, UL, and CSA are theorganizations most commonly referred to in North America.Their ratings are based on similar application descriptionsand expected performance. UL and CSA both requireenclosure testing by qualified evaluators in their labs. Theyalso send site inspectors to make sure a manufacturer adheresto prescribed manufacturing methods and materialspecification. NEMA, on the other hand, does not requireindependent testing and leaves compliance completely up tothe manufacturer.

In Europe, TUV-IEC ratings are based on test methods, thatare similar to UL and CSA. Nevertheless, there aredifferences in how enclosure performance is interpreted. Forexample, UL and CSA test requirements specify that even asingle drop of water entering an enclosure is considered atest failure. In the IEC standards for each protection level(IP) a certain amount of water is allowed to enter theenclosure.

North American enclosure rating systems also include a 4Xrating that indicates resistance to corrosion. This rating is

based on the enclosure’s ability to withstand prolongedexposure to salt water spray.

While a 4X rating is a good indicator that an enclosure canresist corrosion, it does not provide information on how aspecific corrosive agent will affect a given enclosurematerial.

Comparison of Specific Non-Hazardous Applications

Outdoor Locations

Provides a Degree of Protection Type Of EnclosureAgainst the FollowingEnvironmental Conditions 4 4X

Incidental Contact With ♦ ♦The Enclosed Equipment

Rain, Snow, and Sleet* ♦ ♦

Sleet

Windblown Dust ♦ ♦

Hosedown ♦ ♦

Corrosive Agents ♦

Occasional Temporary Submersion

Occasional Prolonged Submersion

* External operating mechanisms are not required to be operable when the enclosure is ice covered

Industry Reference Information 39

Enclosures For Non-Hazardous LocationsNEMA National Electrical Manufacturers Association (NEMA Standard 250) and Electrical and Electronic Manufacturers Association of Canada (EEMAC)

Enclosures are intended for indoor use primarily to provide a degree of protection against contact with the enclosed equipment or locations where unusual service conditions do not exist.

Enclosures are intended for indoor use primarily to provide a degree of protection against limited amounts of falling water and dirt.

Enclosures are intended for outdoor use primarily to provide a degree of protection against windblown dust, rain, and sleet; undamaged by the formation of ice on the enclosure.

Enclosures are intended for outdoor use primarily to provide a degree of protection against falling rain and sleet; undamaged by the formation of ice on the enclosure.

Enclosures are intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose-directed water; undamaged by the formation of ice on the enclosure.

Enclosures are intended for indoor or outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, and hose-directed water; undamaged by the formation of ice on the enclosure.

Enclosures are intended for use indoors or outdoors where occasional submersion is encountered.

Enclosures are intended for indoor use primarily to provide a degree of protection against dust, falling dirt, and dripping non-corrosive liquids.

Enclosures are intended for indoor use primarily to provide a degree of protection against dust, spraying of water, oil, and non-corrosive coolant.

The preceding descriptions are not intended to be complete representations of National Electrical Manufacturers Association standards for enclosures nor those of the Electrical and Electronic Manufacturers Association of Canada.

Underwriters Laboratories Inc. (UL 50 and UL 508)

Indoor use primarily to provide protection against contact with the enclosed equipment and against a limited amount of falling dirt.

Indoor use to provide a degree of protection against limited amounts of falling water and dirt.

Outdoor use to provide a degree of protection against windblown dust and windblown rain; undamaged by the formation of ice on the enclosure.

Outdoor use to provide a degree of protection against falling rain, undamaged by the formation of ice on the enclosure.

Either indoor or outdoor use to provide a degree of protection against falling rain, splashing water, and hose-directed water; undamaged by the formation of ice on the enclosure; resists corrosion.

Either indoor or outdoor use to proved a degree of protection against falling rain, splashing water, and hose-directed water; undamaged by the formation of ice on the enclosure; resists corrosion.

Indoor or outdoor use to provide a degree of protection against entry of water during temporary submersion at a limited depth; undamaged by the formation of ice on the enclosure.

Indoor use to provide a degree of protection against dust, dirt, fiber flyings, dripping water, and external condensation of non-corrosive liquids.

Indoor use to provide a degree of protection against lint, dust seepage, external condensation and spraying of water, oil, and non-corrosive liquids.

Underwriters Laboratories Inc. (UL) shall not be responsible to anyone for the use of or reliance upon a UL Standard by anyone. UL shall not incur any obligation or liability of damages, including consequential damages, arising out of or connection with the use, interpretation of, or reliance upon a UL standard.

Canadian Standards Association (Standard C22.2 Number 94)

General purpose enclosure. Protects against accidental contact with live parts.

Indoor use to provide a degree of protection against dripping and light splashing of noncorrosive liquids and falling dirt.

Indoor or outdoor use; provides a degree of protection against rain, snow, and windblown dust; undamaged by the external formation of ice on the enclosure.

Indoor or outdoor use; provides a degree of protection against rain and snow, undamaged by the external formation of ice on the enclosure.

Indoor or outdoor use; provides a degree of protection against rain, snow, windblown dust, splashing and hose-directed water; undamaged by the external formation of ice on the enclosure.

Indoor or outdoor use; provides a degree of protection against rain, snow, windblown dust, splashing and hose-directed water; undamaged by the external formation of ice on the enclosure; resists corrosion.

Indoor or outdoor use; provides a degree of protection against the entry of water during temporary submersion at a limited depth; undamaged by the external formation of ice on the enclosure; resists corrosion.

Indoor use; provides a degree of protection against circulating dust, lint, fibers, and flyings; dripping and light splashing of non-corrosive liquids; not provided with knockouts.

Indoor use; provides a degree of protection against circulating dust, lint, fibers, and flyings; seepage and spraying of non-corrosive liquids, including oils and coolants.

TypeDesignation

1

2

3

3R

4

4X

6

12

13

AAAAAA

ULNEMA

* These fibers and flyings are non-hazardous materials and are not considered Class III type ignitable fibers or combustible flyings. For Class III type ignitable fibers or combustible flyings see the National Electrical Code, Section 500-6(a).AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAProvides a Degree of Protection Type Of Enclosure

Against the FollowingEnvironmental Conditions 4 4X 12 13

Oil and Coolant Seepage ♦ ♦Oil or Coolant Spraying and Splashing ♦Corrosive Agents ♦Occasional Temporary Submersion

Occasional Prolonged Submersion

Provides a Degree of Protection Type Of EnclosureAgainst the FollowingEnvironmental Conditions 4 4X 12 13

Incidental Contact With The Enclosed Equipment ♦ ♦ ♦ ♦Falling Dirt ♦ ♦ ♦ ♦Falling Liquids and Light Splashing ♦ ♦ ♦ ♦Dust, Lint, Fibers, and Flyings* ♦ ♦ ♦ ♦Hosedown and Splashing Water ♦ ♦

Comparison of Specific Non-Hazardous ApplicationsIndoor Locations

40 Industry Reference Information

International Standards' IP Protection Classification

IEC Publication 529Classification ofDegrees of Protectionby Enclosures,provides a system forspecifying requiredenclosures of electrical equipment.IEC 529 does not specify degrees ofprotection against risk of explosion, orconditions such as moisture (produced,for example, by condensation),corrosive vapors, fungus, or vermin.NEMA Standards Publication 250does test for environmental conditionssuch as corrosion, rust, icing, oil, andcoolants. For this reason, and becausethe tests and evaluations for othercharacteristics are not identical, theIEC enclosure classificationdesignations CANNOT be exactlyequated with NEMA enclosure Typenumbers.

The accompanying table provides across-reference from NEMA enclosureType numbers to IEC enclosureclassification designations. This cross-reference is an approximation based onthe most current available informationof enclosure test performance and isnot sanctioned by NEMA, IEC, or anyaffiliated agency.

To use the table first find theappropriate NEMA rating along thevertical axis and then read across thehorizontal axis for the correspondingIP rating. DO NOT use this table toconvert IEC classification designationsto NEMA Type numbers.

SpecificationIP 2 3

Characteristic letters

1st characteristic numeral(Protection against solid objects)

2nd characteristic numeral(Protection against liquids)

An enclosure with this designation isprotected against the penetration ofsolid objects greater than 12mm andagainst spraying water.

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

First Numeral Second Numeral

IP IP TestsTests

No Protection

Protected againstsolid objects upto 50mm, e.g.accidental touchby hands.

Protected againstsolid objects upto 12mm, e.g. fingers.

Protected againstsolid objects over 2.5mm, e.g. tools and wires.

Protected againstsolid objects over 1mm

Totally protected against dust.

Protected againstdust (limited ingress, no harmful deposit)

No Protection

Protected againstvertically falling drops of water, e.g. condensation.

Protected againstdirect sprays of water up to 15° from vertical.

Protected againstsprays to 60° from vertical.

Protected againstwater sprayed from all directions (limited ingress permitted).

Protected againstlow pressure jets of water from all directions (limited ingress permit-ted).

Protected against strong jets of water.

Protected against the effects of im-mersion between 15cm and 1m.

Protected against long periods of immersion under pressure.

0 0

1 1

2 2

3 3

4 4

5 5

6 6

7

♦ Indicates compliance.

IEC 529 has no equivalents to NEMA enclosure Types 7, 8, 9, 10, or 11.

Type Of Enclosure IP23 IP30 IP32 IP64 IP65 IP66 IP67

4 ♦

4X ♦

12 ♦

13 ♦

Industry Reference Information 41

NEMA, UL, CSA, versus IEC Enclosure Type Cross-Reference(approximate)

(Cannot be used to convert IEC Classifications to NEMA Type Numbers)

Sources of Standards

NationalNEMA Electrical

ManufacturersAssociation

2101 L Street NorthwestWashington, D.C. 20037

NEMA Standards Publication Number250 Enclosures for ElectricalEquipment (1000 Volts Maximum)

NEMA Standards Publication NumberICS6 Enclosures for IndustrialControls and Systems

Electrical/Electronic

EEMAC ManufacturersAssociation ofCanada

10 Carlson CourtSuite 500Rexdale (Toronto), Ontario,Canada M9W 6L2

UnderwritersLaboratoriesInc.

333 Pfingsten RoadNorthbrook, IL 60062

UL 50 Cabinets and Boxes

UL 508 Industrial Control Equipment

UL 870 Wireways, Auxiliary Guttersand Associated Fittings

CanadianStandardsAssociation

178 Rexdale BoulevardRexdale (Toronto), Ontario,Canada M9W 1R3

CSA Standard C22.2 Number 94Industrial Control Equipment for Usein Ordinary (Non-Hazardous)Locations

AAAAAAUL

InternationalElectro-TechnicalCommission

3 Rue de VarembéCH-1211Geneva 20, Switzerland

IEC 529 Classification of Degrees ofProtection Provided by Enclosures

AmericanANSI National

StandardsInstitute

1430 BroadwayNew York, NY 10018

ANSI Z55.1-1967 Gray Finishes forIndustrial Apparatus and Equipment

National FireNFPA Protection

Association

Batterymarch ParkQuincy, MA 02269

NFPA 70 National Electrical Code(1990)

42 Glossary

Glossary

ACCELERATION. The time rate ofchange of velocity. Typical units are ft/sec/sec, meters/sec/sec, and G’s (1 G = 32.17ft/sec/sec = 9.81 m/sec/sec). Accelerationmeasurements are usually made withaccelerometers.

ACCELEROMETER. Sensor whoseoutput is directly proportional toacceleration. Most commonly usepiezoelectric crystals to produce output.

ACCURACY. The quality of freedom frommistake or error, that is, conformity to truth,a rule or a standard; the typical closenessof a measurement result to the true value;the specified amount of error permitted orpresent in a physical measurement orperformance setup.

ACOUSTIC SENSITIVITY. The parameterquantifying output signal picked up by amotion transducer when subjected toacoustic fields.

ALIASING. A phenomenon which canoccur whenever a signal is not sampled atgreater than, twice the maximum frequencycomponent, causes high frequency signalsto appear at low frequencies. Aliasing isavoided by filtering out signals greater than1/2 the sample rate.

ALIGNMENT. A condition whereby theaxes of machine components are eithercoincident, parallel or perpendicular,according to design requirements.

AMPLITUDE. The magnitude of dynamicmotion or vibration. Amplitude isexpressed in terms of peak-to-peak, zeroto-peak, or RMS. For pure sine wavesonly, these are related as follows:

RMS = 0.707 times zero-to-peak;

peak-to-peak = 2 times zero-to-peak.

ANALOG-TO-DIGITAL CONVERTER (A/D, ADC). A device, or subsystem, thatchanges real-world analog data (as fromtransducers, for example) to a formcompatible with digital (binary) processing.

ANALYSIS RANGE (ANALYSISBANDWIDTH). (See FREQUENCY

RANGE.)

ANTI-ALIASING FILTER. A low-pass filterdesigned to filter out frequencies higherthan 1/2 the sample rate in order to preventaliasing.

ANTI-FRICTION BEARING. (SeeROLLING ELEMENT BEARING.)

ASCII (AMERICAN STANDARD CODEFOR INFORMATION INTERCHANGE). Aseven-bit code capable of representingletters, numbers, punctuation marks, andcontrol codes in a form acceptable tomachines.

ASYMMETRICAL SUPPORT. Rotorsupport system that does not provideuniform restraint in all radial directions.This is typical for most heavy industrialmachinery where stiffness in one planemay be substantially different than stiffnessin the perpendicular plane. Occurs inbearings by design, or from preloads suchas gravity or misalignment.

ASYNCHRONOUS. Vibration componentsthat are not related to rotating speed (alsoreferred to as nonsynchronous).

A

ATTENUATION. The reduction of aquantity such as sensitivity: i.e. throughfiltering or cable loading.

ATTRIBUTE. An individual field of a SETrecord or of a POINT record, acharacteristic of a POINT.

AVERAGING. In a dynamic signalanalyzer, digitally averaging severalmeasurements to improve statisticalaccuracy or to reduce the level of randomasynchronous components. (See RMS.)

AXIAL. In the same direction as the shaftcenterline.

AXIAL POSITION. The average position,or change in position, of a rotor in the axialdirection with respect to some fixedreference position. Ideally the reference isa known position within the thrust bearingaxial clearance or float zone, and themeasurement is made with a displacementtransducer observing the thrust collar.

AXIS. The reference plane used in plottingroutines. The X-axis is the frequencyplane. The Y-axis is the amplitude plane.

BACKGROUND NOISE. The total of allnoise when no signal is input into theamplifier. (See BROADBAND NOISE.)

BALANCE RESONANCE SPEED(s). Arotative speed that corresponds to a naturalresonance frequency.

BALANCED CONDITION. For rotatingmachinery, a condition where the shaftgeometric centerline coincides with themass centerline.

BALANCING. A procedure for adjustingthe radial mass distribution of a rotor sothat the mass centerline approaches therotor geometric centerline.

BALL PASS INNER RACE (BPFI). Thefrequency at which the rollers pass theinner race. Indicative of a fault (crack orspall) in the inner race.

BALL PASS OUTER RACE (BPFI). Thefrequency at which the rollers pass theouter race. Indicative of a fault (crack orspall) in the outer race.

BALL SPIN FREQUENCY (BSF). Thefrequency that a roller turns within thebearing. Indicative of a problem with anindividual roller.

BANDPASS FILTER. A filter with a singletransmission band extending from lower toupper cutoff frequencies. The width of theband is determined by the separation offrequencies at which amplitude isattenuated by 3 dB (0.707).

BAND-REJECT. Also known as band stopand notch; a band-reject filter attenuatessignal frequencies within a specified band,while passing out-of-band signalfrequencies; opposite to the bandpassfilter.

BANDWIDTH. The spacing betweenfrequencies at which a bandpass filterattenuates the signal by 3 dB. In ananalyzer, measurement bandwidth is equalto [(frequency span)/(number of filters) x(window factor)]. Window factors are: 1 foruniform, 1.5 for Hanning, and 3.63 for flattop.

BASE STRAIN SENSITIVITY. Theparameter quantifying the unwanted outputsignal picked up by a motion transducerwhen its mounting surface is subjected tomechanical strains.

CAMPBELL DIAGRAM. A mathematicallyconstructed diagram used to check forcoincidence of vibration sources (i.e. 1Ximbalance, 2X misalignment) with rotornatural resonances. The form of thediagram is a rectangular plot of resonantfrequency (Y-axis) versus excitationfrequency (X-axis). Also known as aninterference diagram.

CAPACITANCE. The ratio of the electriccharge stored to the voltage applied acrossconductive plates separated by a dielectricmaterial (C = q/V).

CARTESIAN FORMAT. A graphicalformat consisting of two (2) orthogonalaxes; typically, Y is the vertical axis and Xis the horizontal axis. This format is usedto graph the results of one variable as afunction of another, e.g., vibrationamplitude versus time (Trend), frequencyversus amplitude (Spectrum) and 1Xamplitude versus shaft rotative speed(Bodé).

CASCADE PLOT. (See SPECTRAL

MAP.)

CAVITATION. A condition which canoccur in liquid-handling machinery (e.g.centrifugal pumps) where system pressuredecrease in the suction line and pump inletlowers fluid pressure and vaporizationoccurs. The result is mixed flow which mayproduce vibration.

CENTER FREQUENCY. For a bandpassfilter, the center of the transmission band.

CENTERLINE POSITION. (See RADIAL

POSITION.)

CHANNEL. A transducer and theinstrumentation hardware and relatedsoftware required to display its outputsignal.

CHARGE AMPLIFIER. Amplifier used toconvert charge mode sensor outputimpedance from high to low, makingcalibration much less dependent on cablecapacitance (also, charge converter).

CHARGE MODE ACCELEROMETER.Any piezoelectric accelerometer that doesnot contain an internal amplifier andproduces a high impedance charge signal.

CHARGE SENSITIVITY. A measure of theamount of charge produced by a chargemode accelerometer per unit ofacceleration. Usually given in terms ofpicocoulombs per g of acceleration; written(pC/g). (See COULOMB, VOLTAGE

SENSITIVITY.)

CLIPPING. Clipping is the term applied tothe generally undesirable circumstance inwhich a signal excursion is limited in somesense by an amplifier, ADC, or other devicewhen its full scale range is reached.Clipping may be “hard” in which the signalexcursion is strictly limited at some voltage;or, it may be “soft” in which case theclipped signal continues to follow the inputat some reduced gain above a certainoutput value.

CLONE. The process of exactlyduplicating a SET or a POlNT.

CLOSE. A SET or POINT is consideredCLOSED if the members below it in itshierarchy are not visible. Use LEFTARROW to CLOSE a SET or POINT. ASET or POINT that is marked on its left bya hyphen symbol is CLOSED (not OPEN).Its members are not displayed (not visibleon screen). (Also, See OPEN.)

B

BASELINE SPECTRUM. A vibrationspectrum taken when a machine is in goodoperating condition; used as a referencefor monitoring and analysis.

BAUD RATE (BIT RATE). The rate in bitsper second at which information istransmitted over a serial data link.

BENDER BEAM ACCELEROMETER. Anaccelerometer design which stresses thepiezoelectric element by bending it. Thisdesign is used primarily for low frequency,high sensitivity applications. (SeeCOMPRESSION MODE

ACCELEROMETER, SHEAR MODE

ACCELEROMETER.)

BIAS OUTPUT VOLTAGE. abr. BOV.Syns. Bias Voltage, Rest Voltage. The DCvoltage at the output of an amplifier onwhich the AC motion signal issuperimposed.

BLADE PASSING FREQUENCY. Apotential vibration frequency on any bladedmachine (turbine, axial compressor, fan,etc.). It is represented by the number ofblades times shaft rotating frequency.

BLOCK SIZE. The number of samplesused in a DSA to compute the Fast FourierTransform. Also the number of samples ina DSA time display. Most DSAs use ablock size of 1024. Smaller block sizereduces resolution, larger block sizeincreases resolution.

BLOCKING CAPACITOR. A capacitorplaced in series with the input of a signalconditioning or measurement device whichblocks the DC Bias Voltage but passes theAC Signal.

BODÉ. Rectangular coordinate plot of 1Xcomponent amplitude and phase versusrunning speed.

BOW. A shaft condition such that thegeometric centerline of the shaft is notstraight.

BRINNELING (FALSE). Impressionsmade by bearing roiling elements on thebearing race; typically caused by externalvibration when the shaft is stationary.

BROADBAND NOISE. The total noise ofan electronic circuit within a specifiedfrequency bandwidth. (SeeBACKGROUND NOISE.)

BUFFER. 1) An isolating circuit used toavoid distortion of the input signal by thedriven circuit. Often employed in datatransmission when driving through longcables. 2) A temporary software storagearea where data resides between time oftransfer from external media and time ofprogram-initiated I/O operations.

CAGE (RETAINER). A component ofrolling bearings which constrains therelative motion of the rolling elementscircumferentially around the bearing.

CALIBRATION. Comparison of theperformance of an item of test andmeasuring equipment with a certifiedreference standard.

CALIBRATION CURVE. A graphicalrepresentative of the measured transduceroutput or instrument readout as comparedto a known input signal.

CALIBRATOR. Verifies that theperformance of a device or instrument iswithin its specified limits.

C

Glossary 43

C

COHERENCE. The ratio of coherentoutput power between channels in a dual-channel DSA. An effective means ofdetermining the similarity of vibration at two(2) locations, giving insight into thepossibility of cause and effect relationships.The real part of a complex function. Thecomponent which is in phase with the inputexcitation. In frequency domain analysis,the coincident terms are the cosine termsof the “Fourier transform.”

COHERENCE FUNCTION. Coherence isa frequency domain function generallycomputed to show the degree to which alinear, noise-free relationship existsbetween a system input and the output.Values vary between one and zero, withone being total coherence and zero beingno coherence between input and output.

COMPRESSION MODEACCELEROMETER. An accelerometerdesign which stresses the piezoelectricelement in the compressive direction: i.e.the electrode faces move toward and awayfrom each other. (See BENDER BEAM

ACCELEROMETER, SHEAR MODE

ACCELEROMETER.)

CONDITION MONITORING. Determine ofthe condition of a machine by interpretationof measurements taken either periodicallyor continuously indicating the condition ofthe machine.

CONSTANT BANDWIDTH FILTER. Abandpass filter whose bandwidth isindependent of center frequency. Thefilters simulated digitally in a DSA areconstant bandwidth.

CONSTANT PERCENTAGEBANDWIDTH. A bandpass filter whosebandwidth is a constant percentage ofcenter frequency. 1/3 octave filters,including those synthesized in DSAs, areconstant percentage bandwidth.

CONTINUOUS SPECTRUM. The type ofspectrum produced from non-periodic data.The spectrum is continuous in thefrequency domain (See LINE

SPECTRUM).

COULOMB. symbol C. The SI unit ofelectric charge. The amount of chargetransported by one volt of electricalpotential in one second of time. One (1)picocoulomb = 10-12 coulombs.

CPM. Cycles per minute.

CPS. Cycles per second. Also referred toas Hertz (Hz).

CREST FACTOR. Relation between peakvalue and RMS value (Peak divided byRMS.)

CRITERIA. A means of selecting desireditems from the database. Very helpful ingenerating reports or downloading to theMICROLOG. The types of selection criteriathat can be set are POINTS IN ALARM,ENABLED POINTS, and OVERDUEPOINTS that fit a selectable date range.

CRITICAL MACHINERY. Machines whichare critical to a major part of the plantprocess. These machines are usuallyunspared.

CRITICAL SPEED MAP. A rectangularplot of system natural frequency (Y-axis)versus bearing or support stiffness (X-axis).

DIFFERENTIATION. Representation interms of time rate of change. For example,differentiating velocity yields acceleration.In a DSA, differentiation is performed bymultiplication by jw, where w is frequencymultiplied by 2π. (Differentiation can alsobe used to convert displacement tovelocity.)

DIFFERENTIAL EXPANSION. Themeasurement of the axial position of therotor with respect to the machine casing atthe opposite end of the machine from thethrust bearing. Changes in axial rotorposition relative to the casing axialclearances are usually the result of thermalexpansion during start-up and shutdown.Often incorporated as a measuredparameter on a steam turbine.

DIGITAL FILTER. A filter which acts ondata after it has been sampled anddigitized. Often used in DSAs to provideanti-aliasing protection after internalresampling.

DIGITAL-TO-ANALOG CONVERSION.The process of producing a continuousanalog signal from discrete quantizedlevels. The result is a continuouswaveform designed to match as closely aspossible a previously sampled signal or asynthesized result. Usually followed by alow pass filter.

DISCRETE FOURIER TRANSFORM. Aprocedure for calculating discretefrequency components (filters or lines) fromsampled time data. Since the frequencydomain result is complex (i.e. real andimaginary components), the number ofpoints is equal to half the number ofsamples.

DISPLACEMENT. The change in distanceor position of an object relative to areference.

DISPLACEMENT SENSOR. A transducerwhose output is proportional to the distancebetween it and the measured object(usually the shaft).

DOWNLOAD. Transferring information tothe Microlog from the host computer.

DYNAMIC DATA. Data (steady state and/or transient) which contains that part of thetransducer signal representing the dynamic(e.g., vibration) characteristics of themeasured variable waveform. Typicaldynamic data presentations includetimebase, orbit, frequency-based spectrum,polar, Bodé, cascade, and waterfall.

DYNAMIC MOTION. Vibratory motion of arotor system caused by mechanisms thatare active only when the rotor is turning atspeeds above slow roll speed.

DYNAMIC RANGE. For spectrummeasurements, the difference, in dB,between the overload level and theminimum detectable signal level (above thenoise) within a measurement system. Theminimum detectable signal of a system isordinarily fixed by one or more of thefollowing: noise level; low level distortion;interference; or resolution level. Fortransfer function measurements, theexcitation, weighting and analysisapproaches taken can have a significanteffect on resulting dynamic range.

ECCENTRICITY, MECHANICAL. Thevariation of the outer diameter of a shaftsurface when referenced to the truegeometric centerline of the shaft. Out-of-roundness.

CRITICAL SPEEDS. In general, anyrotating speed which is associated withhigh vibration amplitude. Often, the rotorspeeds which correspond to naturalfrequencies of the system.

CRYSTAL CAPACITANCE. The electricalcapacitance across the terminations of apiezoelectric crystal. Usually given in termsof picofarads; written (pF).

CROSS AXIS SENSITIVITY. A measure ofoff-axis response of velocity andacceleration transducers.

CROSS TALK. Interface or noise in atransducer signal or channel which has itsorigin in another transducer or channel.When using eddy probes, cross talk canoccur when the tips of two (or more) probesare too close together, resulting in theinteraction of electromagnetic fields. Theeffect is a noise component on each of thetransducers’ output signals.

CURRENT REGULATING DIODE. Asemiconductor device which limits andregulates electrical current independent ofvoltage.

CURVEFITTING. Curvefitting is theprocess whereby coefficients of an arbitraryfunction are computed such that theevaluated function approximates the valuesin a given data set. A mathematicalfunction, such as the minimum meansquared error, is used to judge thegoodness of fit.

CYCLE. One complete sequence of valuesof a periodic quantity.

DAMPING. The quality of a mechanicalsystem that restrains the amplitude ofmotion with each successive cycle.Damping of shaft motion is provided by oilin bearings, seals, etc. The dampingprocess converts mechanical energy toother forms, usually heat.

DAMPING, CRITICAL. The smallestamount of damping required to return thesystem to its equilibrium position withoutoscillation.

DATABASE. A group of SETs, subSETs,and POINTs arranged in a hierarchy thatdefine a user’s facilities (i.e., buildings,areas, machine, data gathering locations).Also a top menu bar function in PRISM2.Allows add to, change, and delete of datain the database.

DECIBELS (dB). A logarithmicrepresentation of amplitude ratio, definedas 20 times the base ten logarithm of theratio of the measured amplitude to areference. DBV readings, for example, arereferenced to 1 volt RMS. dB amplitudescales are required to display the fulldynamic range of a DSA.

DEFECT BEARING FREQUENCY.Frequency generated as a result of a defectin a bearing.

DEGREES OF FREEDOM. A phrase usedin mechanical vibration to describe thecomplexity of the system. The number ofdegrees of freedom is the number ofindependent variables describing the stateof a vibrating system.

DELAY. In reference to filtering, refers tothe time lag between the filter input and theoutput. Delay shows up as a frequency-dependent phase shift between output andinput, and depends on the type andcomplexity of the filter.

D

E

EDDY CURRENT. Electrical current whichis generated (and dissipated) in aconductive material in the presence of anelectromagnetic field.

ELECTROMAGNETIC INTERFERENCE.abr.: EMI. The condition in which anelectromagnetic field produces anunwanted signal.

ELECTROMAGNETIC SENSITIVITY. Theparameter quantifying the unwanted outputsignal picked up by a motion transducerwhen subjected to electromagnetic fields.

ELECTROSTATIC DISCHARGE. abr.:ESD. A very high voltage discharge,sometimes accompanied by a spark,caused by static electrical charges acrossa dielectric material, such as air. This is aproblem especially to electronic equipment,in hot, dry environments and plants wherelarge rollers transport textiles or paper andbuild up very large amounts of charge.

ENGINEERING UNITS. In a DSA, refersto units that are calibrated by the user (e.g.in/sec, g’s).

ENVELOPING. Screening technique toenhance pure repetitive elements of asignal.

EXTERNAL SAMPLING. In a DSA refersto control of data sampling by a multipliedtachometer signal. Provides a stationarydisplay of vibration with changing speed.

FAST FOURIER TRANSFORM (FFT). Acomputer (or microprocessor) procedurefor calculating discrete frequencycomponents from sampled time data. Aspecial case of the discrete Fouriertransform where the number of samples isconstrained to a power of 2.

FIELD. One data item of a record.Examples of fields are first name, middleinitial, last name, room number, machineID, etc.

FILTER. Electronic circuitry designed topass or reject a specific frequency band.

FLAT TOP WINDOW. DSA windowfunction which provides the best amplitudeaccuracy for measuring discrete frequencycomponents.

FLUID-FILM BEARING. A bearing whichsupports the shaft on a thin film of oil. Thefluid-film layer may be generated by journalrotation (hydrodynamic bearing), or byexternally applied pressure (hydrostaticbearing).

FOLDING FREQUENCY. Equal to one-half of the sampling frequency. This is thefrequency above which higher signalfrequencies are folded or aliased back intothe analysis band.

FORCED VIBRATION. The oscillation of asystem under the action of a forcingfunction. Typically forced vibration occursat the frequency of the exciting force.

FRAME. Discrete set of elements(numbers) representing a time or frequencydomain function. The numerical size of theelement set is called the frame, block, orrecord size and is generally a power of 2,such as 64, 128, 256, etc. The term, framelength or block length, is used to describethe length of the element set in seconds ormilliseconds and is equal to N D t where Nis the frame size and D t is the samplinginterval.

F

44 Glossary

FREE RUNNING. A term used to describethe operation of an analyzer or processorwhich operates continuously at a fixed rate,not in synchronism with some externalreference event. Analyzers, processorsand computing systems are often thoughtto be operating in a triggered, blocksynchronous or free running mode ofoperation.

FREE VIBRATION. Vibration of amechanical system following an initialforce–typically at one or more naturalfrequencies.

FREQUENCY. The repetition rate of aperiodic event, usually expressed in cyclesper second (Hz), revolutions per minute(RPM), or multiples of rotational speed(orders). Orders are commonly referred toas 1X for rotational speed, 2X for twicerotational speed, etc.

FREQUENCY COMPONENT. Theamplitude, frequency and phasecharacteristics of a dynamic signal.

FREQUENCY DOMAIN. An FFT graph(amplitude versus frequency).

FREQUENCY RANGE. The frequencyrange (bandwidth) over which ameasurement is considered valid; (i.e.,within manufacturer’s specifications).Typical analyzers have selectable ranges.Usually refers to upper frequency limit ofanalysis, considering zero as the loweranalysis limit (See ZOOM ANALYSIS).

FREQUENCY RESPONSE. The amplitudeand phase response characteristics of asystem.

FREQUENCY RESPONSE FUNCTION.The transfer function of a linear systemexpressed in the frequency domain.Commonly defined as the ratio of theFourier transform of the system’s responseto the Fourier transform of the system’sexcitation function as magnitude and phaseor real and imaginary parts. Whereas thetransfer function of a linear system is, in astrict sense, defined as the ratio of theLaPlace transform of the system responseto the LaPlace transform of the LaPlacetransform of the system response to theLaPlace transform of the system input, thefrequency response function is moregenerally used.

FTF. Fundamental Train Frequency.

FUNDAMENTAL. The lowest frequencyperiodic component present in a complexspectrum. At least one complete period ofa signal must be present for it to qualify asthe “fundamental.”

FUNDAMENTAL TRAIN FREQUENCY(FTF). The frequency at which the cagethat contains the rollers rotates. Indicativeof a fault in the cage.

g. A standard unit of acceleration equal toone earth’s gravity, at mean sea level. Theacceleration of free-fall. One g equals32.17 ft/s2 (FPS) or 9.807 m/s2 (MKS).

GAIN. The factor by which an outputsignal exceeds an input signal; theopposite of attenuation; usually expressedin dB.

F GEAR MESH FREQUENCY. A potentialvibration frequency on any machine thatcontains gears; equal to the number ofteeth multiplied by the rotational frequencyof the gear.

GLOBAL BEARING DEFECT. Relativelylarge damage on a bearing element.

GROUND LOOP. Current flow betweentwo or more ground connections whereeach connection is at a slightly differentpotential due to the resistance of thecommon connection.

HANNING WINDOW. DSA windowfunction that provides better frequencyresolution than the flat top window, but withreduced amplitude accuracy.

HARMONIC. Frequency component at afrequency that is an integer multiple of thefundamental frequency.

HEAVY SPOT. The angular location of theimbalance vector at a specific laterallocation on a shaft. The heavy spottypically does not change with rotationalspeed.

HERTZ (Hz). The unit of frequencyrepresented by cycles per second.

HFD. High Frequency Detection. Adynamic high frequency signal from anaccelerometer which includes theaccelerometer’s resonant frequency. Forassessing the condition of rolling elementball or roller bearings.

HIGH-PASS FILTER. A filter with atransmission band starting at a lower cutofffrequency and extending to (theoretically)infinite frequency.

HIGH SPOT. The angular location on theshaft directly under the vibration transducerat the point of closest proximity. The highspot can move with changes in shaftdynamics (e.g. from changes in speed).

IEEE 488 BUS. An industry standard busthat defines a digital interface forprogrammable instrumentation; it uses abyte-serial, bit-parallel technique to handle8-bit-wide data words.

IMBALANCE. Unequal radial weightdistribution on a rotor system; a shaftcondition such that the mass and shaftgeometric centerlines do not coincide.

INFLUENCE COEFFICIENTS.Mathematical coefficients that describe theinfluence of system loading on systemdeflection.

IN-PHASE (DIRECT) MOTIONCOMPONENT. (In F) The Cartesian valueof the 1X vibration transducer angularlocation. This may be expressed as: IN F =A cos Q, where A is the peak to peakamplitude, and Q is the base angle of the1X peak to peak amplitude, and Q is thephase angle of the 1X vector.

INNER RACE. A generally cylindricalcomponent of rolling bearings which ispositioned between the shaft and therolling elements.

INTEGRATED CIRCUITPIEZOELECTRIC. The industry standardpowering scheme using a current limitedvoltage supply for powering internallyamplified accelerometers and PVTs.

H

G

K

J

I

INTEGRATION. A process producing aresult that, when differentiated, yields theoriginal quantity. Integration ofacceleration, for example, yields velocityintegration is performed in a DSA bydividing by jw, where w is frequencymultiplied by 2π. (Integration is also usedto convert velocity to displacement.)

IsoRing®. A bolt through shear modepiezoelectric sensor designs thatelectrically, mechanically, and thermallyisolates the sensing element from thesensor housing. A registered trademark ofWilcoxon Research.

JITTER. Abrupt and spurious shifts in time,amplitude, frequency or phase withwaveforms of either a pulse or continuousnature. Can also be introduced by designas in the case of sample pulse dither.

JOURNAL. Specific portions of the shaftsurface from which rotor applied loads aretransmitted to bearing supports.

KEYPHASOR PHASE REFERENCESENSOR. A signal used in rotatingmachinery measurements, generated by asensor observing a once-per-revolutionevent The keyphasor signal is used inphase measurements for analysis andbalancing. (Keyphasor is a Bently-Nevadaname.)

LATERAL LOCATION. The definition ofvarious points along the shaft axis ofrotation.

LEAD-ZIRCONATE TITANATE. Apiezoelectric ceramic materialcharacterized by a very high activity(sensitivity), broad temperature range, andlong term stability.

LEAKAGE. When power from discretefrequency components extends intoadjacent frequency bands.

LINEAR RANGE. The portion of asensor’s output voltage versus gap curvewithin which the slope (linearity) does notvary significantly from the nominal slope.

LINEARITY. The response characteristicsof a linear system remain constant withinput level. That is, if the response to inputa is A, and the response to input b is B,then the response of a linear system toinput (a + b) will be (A + B). An example ofa nonlinear system is one whose responseis limited by a mechanical stop, such asoccurs when a bearing mount is loose.

LINES. Common term used to describethe filters of a DSA (e.g. 400 line analyzer).

LINE SPECTRUM. The discrete frequencyspectrum produced by the analysis of aperiodic time function. Typically presentedwith fixed bandwidth resolution andnormally contains neither broadband noisenor transient characteristics. Notnecessarily given as a line or bar display.

LOCAL BEARING DEFECT. Relativelysmall damage on a bearing element, forexample, a crack in an outer ring.

LOW-PASS FILTER. A filter whosetransmission band extends from dc to anupper cutoff frequency.

L

LVDT. Acronym for Linear VariableDifferential Transformer. A contactingdisplacement transducer consisting of amoveable core and a stationarytransformer. The core is attached to thepart to be measured and the transformer isattached to a fixed reference. Often usedfor valve position measurements.

MEMORY LENGTH (PERIOD). The sizeof storage, typically expressed in units oftime for a specified sampling rate. Usuallyrefers to the input memory section of anFFT processing system. Also, sometimesreferred to as block or frame length (SeeFRAME). Defined as the sampling interval(∆t) times the number of samples (N) in thedata block.

MEMORY SYNC. A timing pulsecoincident with the starting address of afixed length, recirculating memory. Oftenrefers to an external sync pulse used toclock the loading of a finite length memorywith respect to an externally free-runningprocess, such as during a signal averagingoperation. Also used to refer to a pulseoutput, occurring once each time a fixedlength memory is updated or recirculated.

MODAL ANALYSIS. The process ofbreaking complex vibration into itscomponent modes of vibration, very muchlike frequency domain analysis breaksvibration down to component frequencies.

MODE SHAPE. The resultant deflectedshape of a rotor at a specific rotationalspeed to an applied forcing function. Athree-dimensional presentation of rotorlateral deflection along the shaft axis.

MODULATION, AMPLITUDE (AM). Theprocess where the amplitude of a signal isvaried as a function of the instantaneousvalue of another signal. The first signal iscalled the carrier, and the second signal iscalled the modulating signal. Amplitudemodulation produces a component at thecarrier frequency, with adjacentcomponents (sidebands) at the frequencyof the modulating signal.

MODULATION, FREQUENCY (FM). Theprocess where the frequency of the carrieris determined by the amplitude of themodulating signal. Frequency modulationproduces a component at the carrierfrequency, with adjacent components(sidebands) at the frequency of themodulating signal.

MOUNTING STUD. A threaded screwused to rigidly attach a motion sensor tothe structure under test.

MOUNTING TORQUE. The optimumtorque applied to the sensor whenmounting with a threaded stud.

MULTIPLEXER. A hardware device thatallows multiple channels to be digitized bya single ADC. In a typical scan, themultiplexer scans the input channelssequentially, pausing only long enoughbetween channels to allow the conversionto be completed.

NATURAL FREQUENCY. The frequencyof free vibration of a system. Thefrequency at which an undamped systemwith a single degree of freedom willoscillate upon momentary displacementfrom its rest position

M

N

Glossary 45

N OUTER RACE. For rolling bearings, agenerally cylindrical component which ispositioned between the rolling elementsand the bearing housing.

OUTPUT IMPEDANCE. The electricalimpedance as measured from the output ofan electrical system. The impedance at theoutput of a sensor must be considerablyless than that of the input of themeasurement system.

OVERLAP PROCESSING. Theprocessing time of an FFT computingdevice is the total amount of time requiredto calculate a desired parameter once theloading of input data memory or memorieshas been accomplished. If the timerequired to process and display the resultsis equal to, or less than, the time requiredto sample the data signals and load inputmemories, the processing is said to beperformed on a real time basis. If theprocessing can be performed significantlyfaster than the time required to sample andload signal inputs, it is then possible toperform multiple analyses of the inputsignals on a segmented basis. Theconcept of performing a new analysis on asegment of data in which only a portion ofthe signal has been updated (some olddata, some new data) is referred to asoverlap processing.

PALOGRAM. Waterfall plot turned 90degrees for easier frequency specific trendidentification.

PASSBAND ANALYSIS. Analysis ofsignals (information) that occur in a known,usually restricted bandwidth. Normallyapplies to frequency domain analysis whichdoes not include dc. (See BASEBAND

ANALYSIS.)

PEAK SPECTRA. A frequency domainmeasurement where, in a series of spectralmeasurements, the one spectrum with thehighest magnitude at a specified frequencyis retained.

PEAK-TO-PEAK VALUE. The differencebetween positive and negative extremevalues of an electronic signal or dynamicmotion. (See AMPLITUDE.)

PERIOD. The time required for a completeoscillation or for a single cycle of events.The reciprocal of frequency.

PERIODIC IN THE WINDOW. Termapplied to a situation where the data beingmeasured in a sampled data system isexactly periodic (repeats an integralnumber of times) within the frame length.Results in a leakage-free measurement indigital analysis instrumentation if arectangular window is used. Real signalsare typically not periodic in the windowunless sampling is synchronized to thedata periodicity.

PERIODIC RANDOM NOISE. A type ofnoise generated by digital measurementsystems that satisfies the conditions for aperiodic signal, yet changes with time sothat devices under test respond as thoughexcited in a random manner. Whentransfer function estimates are measuredwith this type of noise for the excitation,each individual measurement is leakagefree and by ensemble averaging, theeffects of system non-linearities arereduced, thus providing benefits of bothpseudorandom and true random excitation.

PERIODIC WAVEFORM. A waveformwhich repeats itself over some fixed periodof time.

PERIODICITY. The repetitivecharacteristic of a signal. If the period is T(sec), then this results in a discretefrequency or line spectrum with energy onlyat frequencies spaced at 1/T (Hz) intervals.

PHASE. A measurement of the timingrelationship between two signals, orbetween a specific vibration event and akey phasor pulse.

PHASE ANGLE. 1) Time displacementbetween two currents or two voltages (ortheir mechanical analogs) or between acurrent and a voltage measured inelectrical degrees where an electricaldegree is 1/360 part of a complete cycle ofthe frequency at which the measurement ismade. 2) The angle A given by A = tan1 x/y, where x and y are the real and imaginaryparts of a complex number.

PHASE REFERENCE. A signal used inrotating machinery measurements,generated by a sensor observing a once-per-revolution event.

PHASE RESPONSE. The phasedifference (in degrees) between the filterinput and output signals as frequencyvaries; usually expressed as lead and lagreferenced to the input.

PHASE SPECTRUM. Phase-frequencydiagram obtained as part of the results of aFournier transform.

PICKET FENCE EFFECT. In general,unless a frequency component coincidesexactly with an analysis line, there will bean error in both the indicated amplitude andfrequency (where the highest line is takenas representing the frequency component).This can be compensated for, provided it isknown (or assumed) that one is dealingwith a single stable frequency component.

PIEZOELECTRIC. Any material whichprovides a conversion between mechanicaland electrical energy. For a piezoelectriccrystal, if mechanical stresses are appliedon two opposite faces, electrical chargesappear on some other pair of faces.

PIEZOELECTRIC ACCELEROMETER. Asensor which employs piezoelectricmaterials to transduce mechanical motioninto an electrical signal proportional to theacceleration.

PIEZOELECTRIC VELOCITYTRANSDUCER. A piezoelectricaccelerometer with on board signalintegration into velocity.

POINT. An ID established in the database.This ID names an entity which is onespecific and unique data collection location.One POINT is required for each specificmeasurement. Both vibration and processPOINTs can be established.

POLAR PLOT. Polar coordinaterepresentation of the locus of the 1X, 2X,3X, ... vector at a specific lateral shaftlocation with the shaft rotational speed as aparameter.

POLARITY. In relation to transducers, thedirection of output signal change (positiveor negative) caused by motion in a specificdirection (toward or away from thetransducer) in the sensitive axis of thetransducer. Normal convention is thatmotion toward the transducer will producea positive signal change.

P

PRELOAD, BEARING. The dimensionlessquantity that is typically expressed as anumber from zero to one where a preloadof zero indicates no bearing load upon theshaft, and one indicates the maximumpreload (i.e., line contact between shaftand bearing).

PRELOAD, EXTERNAL. Any of severalmechanisms that can externally load abearing. This includes “soft” preloads suchas process fluids or gravitational forces, aswell as “hard” preloads from gear contactforces, misalignment, rubs, etc.

PROCESS POINT. POINT type used tomonitor values other than vibration.Readings can be manually entered fromthe keyboard collected directly from certaintypes of instruments. Data values can betrended by the software for comparison ofthese process variables with vibration data.

PROCESSING GAIN. In a digital Fourieranalysis system, the improvement insignal-to-noise ratio between periodiccomponents and broadband noise obtainedby transformation to the frequency domainand observation in that domain. The effectis caused by the noise power being spreadout over all frequencies while the discretesignal power remains constant at fixedfrequencies. Doubling the number offrequency resolution lines provides 3 dB ofprocessing gain; (i.e., the noise floor willappear to be reduced by 3 dB in each cell).

PROM. Programmable Read Only Memorycomputer chip.

PSEUDORANDOM NOISE. A periodsignal generated by repeating a datarecord consisting of a series of randomvalues. This noise has a discrete spectrumwith energy at frequencies spaced at 1/record length (sec).

PYROELECTRIC EFFECT. A property ofmost piezoelectric materials whereby achange in temperature produces acorresponding electrical signal.

RADIAL. Direction perpendicular to theshaft centerline.

RADIAL POSITION. The average location,relative to the radial bearing centerline, ofthe shaft dynamic motion.

RANDOM. Describing a variable whosevalue at a particular future instant cannotbe predicted exactly.

RANDOM VIBRATION (RANDOMNOISE). Vibration whose instantaneousvalue cannot be predicted with completecertainty for any given instant of time.Rather, the instantaneous values arespecified only by probability distributionfunctions which give the probable fractionof the total time that the instantaneousvalues lie within a specified range.

– NOTES –

“Random” means not deterministic.

“White” means uncorrelated (flat PSD).

“Gaussian” describes the shape of thePDF.

“Noise” usually means not the signal.

These are all different, though related.

R

NODAL POINT. A point of minimum shaftdeflection in a specific mode shape. Mayreadily change location along the shaft axisdue to changes in residual imbalance orother forcing function, or change inrestraint such as an increased bearingclearance.

NOISE. Any component of a transduceroutput signal that does not represent thevariable intended to be measured.

NORMAL SENSITIVITY. Syn.: AxialSensitivity. The sensitivity of a motionsensor in the direction perpendicular to thesurface of the mounting structure. (SeeTransverse Sensitivity.)

NOTCH FILTER. A band-elimination filterused to prevent the passage of specificfrequencies.

NULLING. Vector compensation at shaftslow roll speed for 1 X electrical/mechanical runout amplitude and phasethat would otherwise distort vibrationmeasurements at higher shaft speeds.

NYQUIST RATE. The Nyquist rate isequal to twice the highest signal frequencyand is the minimum rate at which the datacan be sampled and still avoid aliasing.

OCTAVE. The interval between twofrequencies with a ratio of 2 to 1.

OIL WHIRL/WHIP. An unstable freevibration whereby a fluid-film bearing hasinsufficient unit loading. Under thiscondition, the shaft centerline dynamicmotion is usually circular in the direction ofrotation. Oil whirl occurs at the oil flowvelocity within the bearing, usually 40–49%of shaft speed. Oil whip occurs when thewhirl frequency coincides with (andbecomes locked to) a shaft resonantfrequency. (Oil whirl and whip can occur inany case where a fluid is between twocylindrical surfaces.)

OPTICAL PICKUP. A non-contactingtransducer which detects the level ofreflectively of an observed surface.Provides a light source directed out of thetip of the pickup. When this light isreflected back to the pickup from theobserved surface, a voltage is generated.

ORBIT. The path of the shaft centerlinemotion during rotation. The orbit isobserved with an oscilloscope connectedto X and Y-axis displacement transducers.Some dual-channel DSAs also have theability to display orbits.

ORDER. A multiple of some referencefrequency. An FFT spectrum plotdisplayed in orders will have multiples ofrunning speed along the horizontal axis.Orders are commonly referred to as 1X forrunning speed, 2X for twice running speed,and so on.

ORDER ANALYSIS. The ability to studythe amplitude changes of specific signalsthat are related to the rotation of the deviceunder test. Orders are numbered by theirrelationship to rotational speed, such assecond order = 2 times RPM; third order =3 times RPM.

OSCILLATION. The variation with time ofthe magnitude of a quantity alternatingabove and below a specified reference.(See Vibration.)

O

RREAL. In a complex signal, the componentthat is in phase with the excitation. Infrequency domain analysis, it is themagnitude of the cosine terms of theFourier series, “Coincident, Co”, as in CO-QUAD analyzer.

REAL-TIME ANALYSIS. Analysis forwhich, on the average, the computingassociated with each sampled record canbe completed in a time less than, or equalto, the record length. In digital analyzers,the functions accomplished during thecomputing time should be specified; (e.g.,Fourier transform, calibration, normalizingby the effective filter bandwidth, averaging,display, etc.).

REAL TIME RATE. For a DSA, thebroadest frequency span at which data issampled continuously. Real time rate ismostly dependent on FFT processingspeed.

RELATIVE MOTION. Vibration measuredrelative to a chosen reference.Displacement transducers generallymeasure shaft motion relative to thetransducer mounting.

REPEATABILITY. The ability of atransducer or readout instrument toreproduce readings when the same input isapplied repeatedly.

RESOLUTION. The smallest change instimulus that will produce a detectablechange in the instrument output.

RESONANCE. The condition of vibrationamplitude and phase change responsecaused by a corresponding systemsensitivity to a particular forcing frequency.A resonance is typically identified by asubstantial amplitude increase, and relatedphase shift.

ROLL-OFF FREQUENCY. syn.: cutofffrequency. The frequency at which a filterattenuates a pass band gain by 3 dB.

ROLL-OFF RATE. Usually refers to a filtercharacteristic. The best straight-line fit tothe slope of the “filter transmissibilitycharacteristic” in the “transition band,”usually expressed in dB per octave.

ROLLING ELEMENT BEARING. Bearingwhose low friction qualities derive fromrolling elements (balls or rollers), with littlelubrication.

ROLLOFF RATE. Also known as “ultimateslope;” filter’s attenuation rate atfrequencies well outside the passband.Expressed as a positive rate of change ofamplitude (in dB/octave or dB/decade offrequency) for a low-pass filter; as anegative attenuation rate for a high-passfilter.

ROOT MEAN SQUARE IRMSR. Squareroot of the arithmetical average of a set ofsquared instantaneous values. DSAsperform RMS averaging digitally onsuccessive vibration spectra.

ROOT MEAN SQUARE RMS. Square rootof the arithmetic average of a set ofsquared instantaneous values. This can beexpressed by an integral as: where x is thedependent variable, t is the independentvariable and T is the period. (SeeAMPLITUDE.)

ROTOR, FLEXIBLE. A rotor whichoperates close enough to, or beyond itsfirst bending critical speed for dynamiceffects to influence rotor deformations.Rotors which cannot be classified as rigidrotors are considered to be flexible rotors.

46 Glossary

ROTOR, RIGID. A rotor which operatessubstantially below its first bending criticalspeed. A rigid rotor can be brought into,and will remain in, a state of satisfactorybalance at all operating speeds whenbalanced on any two arbitrarily selectedcorrection planes.

RPM SPECTRAL MAP. A spectral map ofvibration spectra versus RPM.

RTD. An acronym for Resistance ThermalDevice; a sensor which measurestemperature and change in temperature asa function of resistance.

RUNOUT COMPENSATION. Electroniccorrection of a transducer output signal forthe error resulting from slow roll runout.

RS-232C. A de facto standard, originallyintroduced by the Bell System, for thetransmission of data over a twisted-wirepair less than 50 feet in length; it definespin assignments, signal levels, and soforth, for receiving and transmittingdevices. Other RS-standards cover thetransmission of data over distances inexcess of 50 feet (RS-422; RS-485).

SAMPLING. The process of obtaining asequence of instantaneous values of afunction at regular or intermittent intervals.

SAMPLING RATE. The rate, in samplesper second, at which analog signals aresampled and then digitized. The inverse ofthe sampling interval.

SCALE FACTOR. The Factor by whichthe reading of an instrument must bemultiplied in order to result in the true finalvalue, when a corresponding (but inverse)scale factor was used initially to bring thesignal amplitude within range of theinstrument.

SEISMIC. Refers to an inertiallyreferenced measurement or ameasurement relative to free space.

SCREENING. Transformation of ameasurement to such a form that itenhances the information about a certaindefect.

SEE™ (SPECTRAL EMITTED ENERGY).Technology developed by SKF to measurehigh frequencies (250-350 kHz) associatedwith metal-to-metal contact in rollingelement bearings.

SEISMIC TRANSDUCER. A transducerthat is mounted on the case or housing of amachine and measures casing vibrationrelative to free space. Accelerometers andvelocity transducers are seismic.

SENSITIVITY. The ratio of magnitude ofan output to the magnitude of a quantitymeasured (for example, sensitivity ofmeasuring voltage with an oscilloscope isspecified in centimeters/volt or divisions/volt). Also, the smallest input signal towhich an instrument can respond.

SENSOR. A transducer which senses andconverts a physical phenomenon to ananalog electrical signal.

SHEAR MODE ACCELEROMETER. Anaccelerometer design which stresses thepiezoelectric element in the shear direction:i.e. the electrode faces move parallel toeach other. (See BENDER BEAM

ACCELEROMETER, COMPRESSION

MODE ACCELEROMETER.)

SHOCK LIMIT. The maximum amount ofshort duration mechanical shock that asensor can be subjected to before thepossibility of permanent damage canoccur. (See MECHANICAL SHOCK.)

SIDEBANDS. Additional frequenciesgenerated by frequency modulation.

SIDE LOBE. A response separated infrequency from the main or desiredresponse. Usually refers to a filter shape,particularly in digital filters that havecomplex structure (many notches andpeaks) in the filter transition band

SIGNAL ANALYSIS. Process of extractinginformation about a signal’s behavior in thetime domain and/or frequency domain.Describes the entire process of filtering,sampling, digitizing, computation, anddisplay of results in a meaningful format.

SIGNAL CONDITIONER. A device placedbetween a signal source and a readoutinstrument to change the signal.Examples: attenuators, preamplifiers,signal converters (for changing oneelectrical quantity into another, such asvolts to amps or analog to digital), andfilters.

SIGNAL-TO-NOISE RATIO. A measure ofsignal quality. Typically, the ratio ofvoltage or power of a desired signal to theundesired noise component measured incorresponding units.

SIGNATURE. A vibration frequencyspectrum which is distinctive and special toa particular machine or component, systemor subsystem at a specific point in time,under specific machine operatingconditions. Used for historical comparisonof mechanical condition over the operatinglife of the machine.

SIGNATURE ANALYSIS. The methodwhereby a physical process or device isidentified in terms of the invariantfrequency characteristics of the signal itgenerates.

SIGNATURE ANALYZER. Comparesstored patterns (signatures) againstreceived patterns.

SIMULTANEOUS SAMPLE and HOLD. Indata acquisition systems, the technique ofusing separate sample and hold amplifiersfor each channel. This allowssimultaneous sampling on all channels,thereby eliminating any SKEW due to useof a multiplexer.

SLEW RATE. The large-signal rate-of-change of output of a filter under specificoperating conditions, expressed in volts/microsecond; expresses the fastest rate atwhich a filter output can execute voltagelevel output excursions to within predictedtolerances.

SLOW ROLL SPEED. Low rotative speedat which dynamic motion effects fromforces such as imbalance are negligible.

SPALL. In rolling bearings, a flake or chipof metal removed from one of the bearingraces or from a rolling element. Spalling isevidence of serious bearing degradationand may be detected during normalbearing operation by observing increasesin the signal amplitude of the highfrequency vibrations signals.

SPECTRAL MAP. A three-dimensionalplot of the vibration amplitude spectrumversus another variable, usually time orRPM.

SPECTRUM. The distribution of theamplitude of the components of a timedomain signal as a function of frequency.

SPECTRUM ANALYZER. An instrumentwhich displays the frequency spectrum ofan input signal.

STATIC DATA. Data which describes thequantitative characteristics of themeasured parameter. Static data can alsoinclude quantitative values describing theconditions under which the parameter wasmeasured. For condition monitoringpurposes, static data is typically presentedin various forms of trend graphs anddisplays/lists of current values. Examplesof static data include vibration amplitude,phase lag angle, frequency, vector,average shaft position, shaft rotativespeed, time, date, monitor alarm and OKstatus.

STEADY STATE DATA. Data (static and/or dynamic) acquired from a machinewhich is on-line, under (relative) constantoperating conditions (shaft rotative speed,load).

STIFFNESS. The spring-like quality ofmechanical and hydraulic elements toelastically deform under load.

STRAIN. The physical deformation,deflection, or change in length resultingfrom stress (force per unit area).

STRAIN GAUGE. A transducer whichreacts to changes in load, typically throughchanges in resistance.

SUBHARMONIC. Sinusoidal quantity of afrequency that is an integral submultiple ofa fundamental frequency.

SUBSYNCHRONOUS. Component(s) of avibration signal which has a frequency lessthat shaft rotative frequency.

SYNC PULSE. A trigger pulse which isused to synchronize two or moreprocesses.

SYNCHRONOUS. The component of avibration signal that has a frequency equalto the shaft rotative frequency (1X).

SYNCHRONOUS TIME DOMAIN. Adynamic amplitude vs. time graph (timedomain) of data averaged in relation to asynchronous trigger pulse.

SYSTEM IDENTIFICATION. The processof modeling a dynamic system andexperimentally determining values ofparameters in the mathematical modelwhich best describes the behavior of thesystem.

TEMPERATURE RANGE. Thetemperature span, given by thetemperature extremes, over which thesensor will perform without damage.Specifications within the temperature rangemay vary as a function of temperature.

TEMPERATURE RESPONSE. A measureof the change in a quantity, usuallysensitivity, as a function of temperature.

THERMOCOUPLE. A temperaturesensing device comprised of two dissimilarmetal wires which, when thermally affected(heated or cooled), produce a proportionalchange in electrical potential at the pointwhere they join.

THRESHOLD. The smallest change in ameasured variable that will result in ameasurable change in an output signal.

THROUGH-PUT. Amount of workperformed by a system (e.g., number ofbatch jobs per hour processed by acomputer).

S

T

TRIBOELECTRIC EFFECT. Electricalnoise caused by cable motion. When acable is bent, the displacement of oneconductor relative to the other introduces aspurious signal. Particularly problematicwith high impedance electrical systems,such as charge mode accelerometers.

TRIGGER. Any event which can be usedas a timing reference. In a DSA, a triggercan be used to initiate a measurement.

TRIP MULTIPLIER. That function providedin a monitor system to temporarily increasethe alarm (Alert and Danger) set pointvalues by a specific multiple. This functionis normally applied by manual (operator)action during start-up to allow a machine topass through critical speed ranges withoutnuisance monitor alarm indications.

TSI. Acronym for Turbine SupervisoryInstrumentation. A TSI system is acontinuous monitoring system generallyused on turbogenerator sets. It can includesuch measurement parameters as shaftradial vibration, axial thrust position,differential expansion, case expansion,valve position, and shaft rotative speed.The TSI system consists of measurementsensors, monitors, interconnecting wiringand a microprocessor-based monitoring/data acquisition system.

TTL (TRANSISTOR-TRANSISTORLOGIC). A logic family characterized byhigh speeds, medium power consumption,and wide usage.

UNBALANCE. (See IMBALANCE.)

UNIFORM WINDOW. In a DSA, a windowfunction with uniform weighting across thetime record. This window does not protectagainst leakage, and should be used onlywith transient signals contained completelywithin the time record.

UPLOAD. Transferring collected data fromthe MICROLOG to the host computer.

VALVE POSITION. A measurement of theposition of the process inlet valves on amachine, using expressed as a percentageof the valve opening; zero percent is fullyclosed, 100 percent is fully open. Oftenincorporated as a measured parameter onsteam turbines.

VANE PASSING FREQUENCIES. Apotential vibration frequency on vanedimpeller compressors, pumps, and othermachines with vaned rotating elements. Itis represented by the number of vanes (onan impeller or stage) times shaft rotativefrequency.

VECTOR. A quantity which has bothmagnitude and direction (phase).

VELOCITY. The time rate of change ofdisplacement. This if often expressed asV, x or dx/dt; velocity leads displacementby 90 degrees in time. Typical units forvelocity are inches/second or millimeters/second, zero to peak. Velocitymeasurements are usually obtained with anaccelerometer and integrated to velocity ora mechanically activated velocitytransducer and are used to evaluatemachine housing and other structuralresponse characteristics. Electronicintegration of a velocity signal yieldsdisplacement.

T

V

VELOCITY SENSOR. Anelectromechanical transducer, typically ofseismic design, used for measuringbearing housing and other structuralvibration. This transducer measuresabsolute vibration, relative to a fixed pointin space.

VIBRATION. Magnitude of cyclic motion;may be expressed as acceleration,velocity, or displacement. Defined byfrequency and timebase components.

VIBRATION LIMIT. The maximum amountof vibration that a sensor can be subjectedto before the possibility of permanentdamage can occur.

WATERFALL PLOT. (See SPECTRAL

MAP.)

WAVEFORM. A presentation or display ofthe instantaneous amplitude of a signal asa function of time. A vibration waveformcan be observed on an oscilloscope in thetimebase mode.

WINDOW. When a portion only of a recordis analyzed, that portion is called a window.A window can be expressed in either thetime domain or in the frequency domain,although the former is more common. Toreduce the edge effects, which causeleakage, a window is often given a shapeor weighting function. A window in the timedomain is represented by a multiplicationand, hence, is a convolution in thefrequency domain. A convolution can bethought of as a smoothing function. Thissmoothing can be represented by aneffective filter shape of the window; energyat a frequency in the original data willappear at other frequencies as given by thefilter shape. Since time domain windowscan be represented as a smoothingfunction in the frequency domain, the timedomain windowing can be accomplisheddirectly in the frequency domain.

U

W

ZERO TO PEAK VALUE. One-half of thepeak to peak value. (See AMPLITUDE.)

ZOOM. Feature to magnify portions of aselected spectrum plot for more detailedexamination.

ZOOM ANALYSIS. A zoom analysis is atechnique for examining the frequencycontent of a signal with a fine resolutionover a relatively narrow band offrequencies. The technique basically takesa band of frequencies and translates themto a lower band of frequencies, where thesignals can be decimated to reduce thesample size. A standard analyzer can thenbe used to analyze the data.

– NOTE –

That the increased resolution of thistechnique requires a corresponding

increase in the time record length. Thesample rate is decreased by decimation,to reduce the number of samples in the

time window, only after thedemodulation.

Glossary 47

ZTHRUST POSITION. (See AXIAL

POSITION.)

TIME AVERAGING. In a DSA, averagingof time records that results in reduction ofasynchronous components.

TIMEBASE DISPLAY/PLOT. Apresentation of instantaneous amplitude ofa signal as a function of time. A vibrationwaveform can be observed on anoscilloscope in the time domain.

TIME DOMAIN. A dynamic amplitudeversus time graph.

TIME LAG. In correlation analysis onecalculates an integral of the product of onesignal and a temporally displaced signal.The time difference between the twosignals is referred to as the time-lag.

TIME RECORD. In a DSA, the sampledtime data converted to the frequencydomain by the FFT. Most DSAs use a timerecord of 1024 samples.

TIME RECORD LENGTH. The total lengthof time over which a time history isobserved. This total time may be brokenup into several shorter data blocks.

TIMESTAMP. Current date assigned attime of data collection or event.

TIME SYNCHRONOUS. A data samplingand/or processing technique in which thebeginning or ending of a data block issynchronized with an external event.

TIME WINDOW. The time record is oftendivided into segments and each segment isanalyzed as a unit or frame of data. Eachframe is called a block or time window.(See WINDOW.)

TORQUE. A measure of the tendency of aforce to cause rotation, equal to the forcemultiplied by the perpendicular distancebetween the line of action of the force andthe center of rotation.

TORSIONAL VIBRATION. Amplitudemodulation of torque measured in degreespeak-to-peak referenced to the axis ofshaft rotation.

TRACKING FILTER. A low-pass orbandpass filter which automatically tracksthe input signal. A tracking filter is usuallyrequired for aliasing protection when datasampling is controlled externally.

TRANSDUCER. (See SENSOR.)

TRANSIENT ANALYSIS. When theexcitation of a system is of finite duration,the analysis of the data is a transientanalysis. A transient analysis can also beused to study the change from one steady-state to a second steady-state condition.

TRANSIENT VIBRATION. Temporarilysustained vibration of a mechanicalsystem. It may consist of forced or freevibration or both. Typically this isassociated with changes in machineoperating condition such as speed, load,etc.

TRANSVERSE SENSITIVITY. syn.: CrossAxis Sensitivity. The parameter quantifyingthe unwanted output signal picked up by amotion transducer when subjected tomotion perpendicular to the normal axis ofoperation. The transverse sensitivity isusually given in terms of the maximumpercent of the normal axis sensitivity.

Trademarks used in this publication.

RYTON® is a registered trademark of Phillips Chemical Company.

TEFLON® is a registered trademark of DuPont.

UL® is a registered trademark of Underwriters Laboratories Inc.

CSA® is a registered trademark of Canadian Standards Association.

National Electric Code® is a registered trademark of National Fire ProtectionAssociation.

SKF Condition Monitoring®

SKF Condition Monitoring Area Centers Your SKF Condition Monitoring Representative:North and South America Europe, Middle East, Africa Asia, Pacific4141 Ruffin Road Postbus 2091 Kawasan Perindustrian NilaiSan Diego, California 92123 USA 5300 CB Zaltbommel P. O. Box 26, 71807 NilaiTelephone (858) 496-3400 The Netherlands Negeri Sembilan Darul Khusus, MalaysiaFAX (858) 496-3531 Telephone (+31) 418-681818 Telephone (+60) 6-799-2713Web: www.skfcm.com FAX (+31) 418-681800 FAX (+60) 6-799-2407

CM2004 (Revised 6-00) Copyright © 2000 by SKF Condition Monitoring, Inc. ALL RIGHTS RESERVED

Although care has been taken to assure the accuracy of the data compiled in this publication, SKFdoes not assume any liability for errors or omissions. SKF reserves the right to alter any part ofthis publication without prior notice.

SKF is a registered trademark of SKF USA Inc.

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