Commissioning Motors and Generators

Note: The source of the technical material in this volume is the ProfessionalEngineering Development Program (PEDP) of Engineering Services.

Warning: The material contained in this document was developed for SaudiAramco and is intended for the exclusive use of Saudi Aramco’s employees.Any material contained in this document which is not already in the publicdomain may not be copied, reproduced, sold, given, or disclosed to thirdparties, or otherwise used in whole, or in part, without the written permissionof the Vice President, Engineering Services, Saudi Aramco.

Chapter : Electrical For additional information on this subject, contactFile Reference: EEX30205 W.A. Roussel on 874-6160

Engineering EncyclopediaSaudi Aramco DeskTop Standards

Commissioning Motors And Generators

Engineering Encyclopedia Electrical

Commissioning Motors and Generators

Saudi Aramco DeskTop Standards

Content Page

INTRODUCTION................................................................................................................ 1

SAUDI ARAMCO REQUIREMENTS................................................................................. 2

Motor and Generator Standards and Specifications.................................................... 2

NEMA MG-1............................................................................................................ 3

Size Classification .......................................................................................... 3

Application Classification............................................................................... 4

Variability of Speed Classification .................................................................. 4

Electrical Types Classification........................................................................ 5

Enclosure and Method of Cooling Classification ............................................ 6

EVALUATING MOTORS AND GENERATORS UPON RECEIPT ................................... 8

Visual Inspection....................................................................................................... 8

Verification Against Specifications ............................................................................ 8

Motor and Generator Nameplates .................................................................. 9

EVALUATING MOTOR AND GENERATOR INSTALLATION AND TESTING............12

Visual Inspection......................................................................................................12

Suitability .....................................................................................................13

Physical Damage...........................................................................................13

Personnel Protective Devices ........................................................................14

Cleanliness....................................................................................................14

Area Classification ........................................................................................14

Mechanical Inspection ..............................................................................................14

Mounting Bolts.............................................................................................15

Motor Alignment ..........................................................................................15

Shaft Rotation...............................................................................................15

Lubrication ...................................................................................................16

Rotor to Stator Air Gap Alignment ...............................................................16

Electrical Inspection and Test ...................................................................................16

Winding Resistance.......................................................................................17

Insulation Resistance.....................................................................................17




Dc High-Pot .................................................................................................19

Miscellaneous Electrical Tests.......................................................................21

Energization Tests ........................................................................................21

WORK AID 1: REFERENCES FOR EVALUATING MOTORSAND GENERATORS UPON RECEIPT ...................................................24

Work Aid 1A: Motor and Generator Technical and Construction Requirements........24

Method of Bearing Lubrication .....................................................................27

Work Aid 1B: Motor and Generator Winding, Wiring, and Space HeaterRequirements ....................................................................................33

Work Aid 1C: Motor Rating Requirements ..............................................................35

Work Aid 1D: Data Schedules..................................................................................36

WORK AID 2: REFERENCES FOR EVALUATING MOTOR ANDGENERATOR INSTALLATION AND TESTING ...................................42

Work Aid 2A: Testing Requirements........................................................................42

Work Aid 2B: Information, Formulas, and Tables for Use in Evaluating theResults of Insulation Resistance (Megger) Tests ................................43

Work Aid 2C: Information, Formulas, and Tables for Use in Evaluating theResults of Dc High-Pot Tests ............................................................44

Work Aid 2D: Miscellaneous Tests/Checks ..............................................................46

Rotating Rectifier Diode Check.....................................................................46

Air Gap Check..............................................................................................47

Work Aid 2E: Acceptable Values for No Load Run Test Data .................................47

Phase Current ...............................................................................................47

Phase Voltage...............................................................................................47

Percent Voltage Unbalance ...........................................................................47

Vibration Levels ...........................................................................................48

Winding Temperature ...................................................................................48

Bearing Temperature ....................................................................................48

% Ns When Excited......................................................................................48

Exciter Field Current.....................................................................................49

Motor Field Current......................................................................................49

Power Factor ................................................................................................49




Reactive Power (kVAR) ...............................................................................49

Work Aid 2F: Acceptable Values for Load Run Test Data .......................................49

Inspection/Check of Motor Alignment ..........................................................49

Phase Current ...............................................................................................49

Phase Voltage...............................................................................................50

Percent Voltage Unbalance ...........................................................................50

Vibration Levels ...........................................................................................50

Winding Temperature ...................................................................................51

Bearing Temperature ....................................................................................51

Voltage Dip on Start (%)..............................................................................51

Acceleration Time (Sec)................................................................................51

% Ns When Excited......................................................................................51

Exciter Field Current.....................................................................................51

Motor Field Current......................................................................................51

Power Factor ................................................................................................52

Reactive Power (kVAR) ...............................................................................52

Work Aid 2G: Saudi Aramco Pre-Commissioning Form ...........................................52

Work Aid 2H: Excerpts from GI 2.710.....................................................................71

GLOSSARY........................................................................................................................74




Table of Figures Page

Figure 1: Ac Medium Machine Ratings (From NEMA MG-1-1987) ......................... 4

Figure 2: Typical Results of High-Pot Tests.............................................................20

Figure 4: Saudi Aramco Motor and Generator Material and InstallationRequirements (from SAES-P-113) ..........................................................25

Figure 5: Motor Construction Technical Requirements ............................................26

Figure 6: Critical Speeds of Motors .........................................................................26

Figure 7: Bearing Types ..........................................................................................27

Figure 8: Bearing Lubricants ...................................................................................27

Figure 9: Sleeve Bearing Lubrication .......................................................................27

Figure 10: Motor and Generator Bearing Technical Requirements ...........................28

Figure 11: Mechanical Noise and Vibration Monitoring ...........................................28

Figure 12: Motor Enclosure Protection and Specification Requirements. .................29

Figure 13: Maximum Allowable Insulation Temperature ..........................................30

Figure 14: Motor Enclosure Cooling Requirements .................................................30

Figure 15: Nameplate Construction and Minimum Information Requirements ..........31

Figure 16: NEMA Frame Induction Motor Technical Requirements for Motorsthat are Rated Less Than 0.746 KW (from 17-SAMSS-503) ...................32

Figure 17: Motor and Generator Winding Construction Requirements .....................33

Figure 18: Wiring and Grounding Requirements ......................................................34

Figure 19: Space Heater Design and Construction Requirements .............................34

Figure 20: Space Heater Temperature Requirements for Classified Areas.................35

Figure 21: Motor Selection Table (from SAES-P-113) ............................................35

Figure 22: Ac Motor Locked-Rotor KVA per Horsepower (From NEMA MG-1) ...36

Figure 23: NEMA Frame Motor Data Schedule (from 17-SAMSS-503) ..................37

Figure 24: Induction Motor Data Schedule (from 17-SAMSS-502) .........................38

Figure 24: Induction Motor Data Schedule (from 17-SAMSS-502) (Cont'd)............39

Figure 25: Synchronous Motor Data Schedule (from 17-SAMSS-502) ....................40

Figure 25: Synchronous Motor Data Schedule (from 17-SAMSS-502) (Cont'd) ......41

Figure 26: Dielectric Absorption Ratio Chart...........................................................44




Figure 27: Typical Results of High-Pot Tests...........................................................46

Figure 28: Radial Air Gap Values ............................................................................47

Figure 29: Saudi Aramco Pre-Commissioning Form, P-019, NEMAFrame, Form Wound Induction and Synchronous Motors........................53

Figure 29: Saudi Aramco Pre-Commissioning Form, P-019, NEMA Frame,Form Wound Induction and Synchronous Motors (Cont'd)......................54




















Figure 30: GI 2.710 Excerpt....................................................................................72

Figure 30: GI 2.710 Excerpt (Cont'd) ......................................................................73



Saudi Aramco DeskTop Standards 1

INTRODUCTION

Once a motor or generator for a given installation is chosen, the motor or generator is ordered,shipped, and received. Once received, the motor is receipt inspected and tested as part of thecommissioning process. The commissioning process for motors and generators in Saudi Aramcofacilities ensures that a safe and cost-effective system is installed that performs to thespecifications of the facility for the projected operating lifetime of the facility. Experience hasshown that the time and effort that is expended up front to ensure safety, quality control, andadherence to Saudi Aramco and industry standards minimize subsequent equipment failure.

The motor and generator commissioning process involves evaluations, verifications, and checksthat determine whether the proper equipment specifications and installation requirements are met.Tests are performed, and the test results are evaluated to determine whether the motor orgenerator will operate properly and safely after it is installed. When a motor or generator issatisfactorily inspected and tested during the commissioning process, it should operate inaccordance with manufacturer's specifications for its maximum useful life.

Electrical Engineers must be able to direct commissioning of new motors and generators. ThisModule provides information on the following topics that are pertinent to the commissioning ofmotors and generators for Saudi Aramco installations:

• Saudi Aramco Requirements

• Evaluating Motors and Generators Upon Receipt

• Evaluating Motor and Generator Installation and Testing




SAUDI ARAMCO REQUIREMENTS

Large process and process support equipment relies on motors for primary and ancillary functionsthroughout the manufacturing process (e.g., fans, circulation pumps, and blowers). Generators areused to supply power to motors and other equipment. Although motors and generators areusually at the opposite ends of the electrical distribution system (i.e., motors use the power thatgenerators supply), they are similar in construction. Motors and generators have a shaft, arotating element (rotor), a stationary element (stator), and an enclosure. The use of motors andgenerators in industrial settings requires that the motor or generator enclosure provide protectionagainst industrial environmental hazards, such as dust or moisture. Because of the heat that iscreated by motors and generators, some type of cooling system must be also provided.

From this brief overview, it should be clear that the design and construction requirements formotors and generators are similar. During the commissioning process, the Electrical Engineer willbe required to be familiar with the design and construction requirements of motors andgenerators. This section of the module will describe the Saudi Aramco requirements for motorsand generators.

Motor and Generator Standards and Specifications

Several Saudi Aramco standards and specifications contain minimum design and technicalrequirements for motors and generators that are installed in Saudi Aramco facilities. Each ofthese Saudi Aramco documents uses the National Electrical Manufacturers Association (NEMA)Standard MG-1 as a base reference. The following paragraphs contain a brief overview of theSaudi Aramco standards and specifications that are to be used during the commissioning processfor motors and generators.

The minimum mandatory requirements for the procurement and installation of induction andsynchronous motors and generators that are installed in Saudi Aramco industrial facilities aredefined in SAES-P-113, Motors and Generators.

The minimum mandatory technical requirements for 460 V and below, 60 Hz, NEMA Frameinduction motors that are rated from 0.746 to 185 KW (1 hp through 250 hp) that are installed inSaudi Aramco industrial facilities are defined in 17-SAMSS-503, NEMA Frame Motors. 17-SAMSS-503 does not cover submersible motors, overhead crane motors, and valve-operatormotors.

The minimum mandatory technical requirements for form-wound squirrel-cage induction andbrushless salient-pole synchronous motors that are installed in Saudi Aramco industrial facilitiesare defined in 17-SAMSS-502, Form Wound Induction and Synchronous Motors. 17-SAMSS-502 covers form-wound squirrel-cage induction and brushless salient-pole synchronous motorsthat are rated 150 kW (200 hp) and above.




The minimum technical requirements for three-phase, 60 Hz, synchronous generators that arerated 125 kVA (100 kW) through 1250 kVA (1000 kW) that are installed in Saudi Aramcoindustrial facilities are defined in 17-SAMSS-510, Synchronous Generators.

NEMA MG-1

MG-1 is a NEMA publication that contains motor and generator standards. The NEMA MG-1publication is intended to assist users in the proper selection and application of motors andgenerators. The type of information that is contained in NEMA MG-1 pertains to theconstruction, the manufacture, the performance, the safety, and the testing of ac and dc motorsand generators. A detailed discussion of the different types of motors and how they aredesignated by NEMA MG-1 is beyond the scope of this Module; however, a brief overview of theclassifications of motors and generators will be provided. For a detailed discussion of motors andgenerators, refer to EEX 203, Motors and Generators. In accordance with MG-1, motors andgenerators can be classified by size, application, variability of speed, electrical type, and enclosureand method of cooling.

Size Classification

The machine size classifications are small, medium, and large. The sizing of small and mediummachines can depend on frame measurement parameters as well as ratings. Medium dc machinesare machines that have a continuous, open construction rating of up to and including 1.25 hp perrpm for motors or 1.0 kW per rpm for generators. Dc machines that have higher ratings areconsidered large machines. Medium ac machines are machines that have a continuous, openconstruction up to the values that are provided in Figure 1. Ac machines that have higher ratingsare considered to be large machines. For commissioning Saudi Aramco motors or generators, thesize requirements for the particular installation must be met and will vary from installation toinstallation.




Figure 1: Ac Medium Machine Ratings (From NEMA MG-1-1987)

Application Classification

There are three main application classifications for motors in accordance with NEMA MG-1:general purpose (both dc and ac), industrial (both ac and dc), and definite and special purposemotors. The basic difference between general purpose and industrial motors is that the industrialmotors generally have larger ratings and more stringent construction and performancecharacteristics. Definite and special purpose motors have application-specific rating, construction,and performance characteristics. During the commissioning process, the Electrical Engineer mustensure that the application classification of the motor that is being commissioned is correct for theinstallation.

Variability of Speed Classification

The classifications of motors according to variability of speed are dependent upon how the motorspeed reacts to a varying load, and whether the speed of the motor can be controlled. For motorcommissioning, the Electrical Engineer must ensure that the variability of speed classification ofthe motor must be the best fit for the motor application. The variability of speed classificationsare as follows:




• Constant-Speed Motor

• Varying-Speed Motor

• Adjustable-Speed Motor

• Adjustable Varying-Speed Motor

• Multi-Speed Motor

Electrical Types Classification

The classification of motors and generators by electrical type is one of the main ways in whichmotors and generators are specified or described for installations. For Saudi Aramco motor orgenerator commissioning, the Electrical Engineer must determine that the electrical type of themotor or generator matches the electrical type that is required for the installation. The ElectricalEngineer makes the determination by comparing the electrical type of the motor or generator tothe electrical type that is required by the electrical drawings or prints. In accordance with NEMAMG-1, the major electrical type classifications of motors and generators are as follows:

• Ac Motors

- Induction- Synchronous- Polyphase- Single-Phase- Universal

• Ac Generators

- Induction- Synchronous

• Dc Motors

- Shunt-Wound- Series-Wound- Compound-Wound

• Dc Generators

- Shunt-Wound- Compound-Wound




Enclosure and Method of Cooling Classification

The classification of motors and generators according to the enclosure and methods of cooling isanother way to specify motors and generators for installations that is widely used in industry.

NEMA MG-1 allows the use of numerous types of motor enclosures; however, only the followingthree types of NEMA MG-1 enclosures are approved for use in Saudi Aramco applications:

• Totally-enclosed fan-cooled (TEFC).

• Environmental protection totally-enclosed air-to-air cooled (CACA).

• Weather protect type II (WP-II).

NEMA MG-1 defines a TEFC enclosure as a totally-enclosed fan-cooled machine that is equippedfor exterior cooling through use of a fan or fans that are integral with the machine but that areexternal to the enclosing parts. TEFC enclosures without heat exchangers are not permitted formotors that are rated above 11,000 kW (15,000 hp). This requirement is due to the heatdissipation requirements of the motor.

NEMA MG-1 defines a CACA as a totally-enclosed air-to-air cooled machine that is cooledthrough circulation of the internal air through a heat exchanger that, in turn, is cooled throughcirculation of external air. A CACA enclosure is provided with an air-to-air heat exchanger forcooling the internal air, a fan or fans that are integral with the rotor shaft or separate forcirculating the internal air, and a separate fan for circulating the external air. CACA enclosuresshould be specified for induction motors and for salient pole synchronous motors that are rated upto 11,000 kW (15,000 hp).

NEMA MG-1 defines a WP-II as an open machine with ventilating passages that are soconstructed as to minimize the entrance of rain, snow, and air-borne particles to the electric parts,and with ventilated openings that are so constructed as to prevent the passage of a cylindrical rodthat is 0.75 inch in diameter. The WP-II type of enclosure does not afford the same degree ofprotection as TEFC types, but it may be acceptable for synchronous motors with rated outputsthat are above 11,000 kW (15,000 hp) where the cost advantage over a TEFC type of enclosure issignificant.




In addition to environmental protection and methods of cooling, machine enclosures are alsoclassified for installation in hazardous areas. There are many different types of hazardous areas;however, only the usual Class I, Division 1 and 2 locations with Group D hazards that are foundin Saudi Aramco installations will be discussed. For a Division 1 area, the motor enclosure mustbe explosion proof (Exd). Because of the TEFC ruggedness and simplicity, the totally-enclosedflameproof motor is preferred for motor sizes up to about 500 kW (700 hp). For larger motorsizes, the normal practice is to avoid Division 1 locations because of the cost of the enclosures.For a Division 2 area, the motor enclosure must be non-sparking (Exn). The type of protection"n" is such that during normal operation, the motor is not capable of causing ignition, and a faultthat is capable of causing ignition is not likely to occur; therefore, any type of enclosure thatprevents sparks can be utilized.




EVALUATING MOTORS AND GENERATORS UPON RECEIPT

The installation of motors and generators in Saudi Aramco facilities is a process that occurs overa period of time. The motors drive equipment (e.g., pumps) that forms the base of themanufacturing or refining process. The generators supply power to the equipment. Motor andgenerator installations begin with an identified need for motors or power generation equipment ina new facility. After the facility design is approved, the machines are ordered from themanufacturer. When the machines are received from the manufacturer, they must be evaluated toensure that they are proper for the installation. The purpose of the evaluation is to verify thatcorrect motors or generators were received from the manufacturer and that the proper installationspecifications and parameters were met. This section will describe how motors and generators areevaluated upon receipt.

Visual Inspection

When motors or generators are received from the manufacturer, a visual inspection should beperformed. The purpose of the visual inspection is to verify that the motors or generators thatwere received from the manufacturer are in good physical condition and that the enclosures andcooling equipment (if present) have not been damaged during shipment. During the initial visualinspection, the inspection personnel look for obvious equipment damage and determine whetherall necessary equipment (e.g., connection boxes or conduit boxes) are present. A detailedinspection of the motor or generator is also performed when they are completely installed at thesite or facility.

Verification Against Specifications

When a new facility or facility modification is at the equipment installation stage, the design of theinstallation has already been completed. The type and classification of a motor or a generator thatis selected for a specific installation should be shown in the drawings, prints, or specifications forthe installation. The purpose of verifying motors or generators against the specifications is toensure that the machine that is being installed meets Saudi Aramco and industry standards.




Generally, the verification against specifications consists of a determination of whether themachine that is to be installed matches the machine that is specified for the installation. In mostcases, this determination is accomplished by reading an electrical plan that identifies the motor orgenerator size, application, speed control, electrical type, enclosure type, and method of cooling.The Electrical Engineer inspects the manufacturer's nameplate data on the machine, and hecompares them to the requirements on the electrical plan to determine whether the correctmachine is being used. In other situations, the Electrical Engineer must rely on his knowledge ofthe correct application of motors and generators (e.g., types and enclosures) to determine whetherthe correct machine is being used. The data sheets that were used to order the machine from themanufacturer should also be consulted. Example data sheets are provided in Work Aid 1. Anyquality control, quality assurance, and test data that are provided with the motor or generator bythe manufacturer should also be reviewed.

Motor and Generator Nameplates

All motors and generators that are used in Saudi Aramco facilities should have a nameplate that isclearly visible on the machine. The nameplate should contain manufacturer-type information. Theinformation that describes the machine manufacturer's information should consist of themanufacturer's name, the type designation, and the serial number. Because of the different typesand classifications of motors and generators, nameplates may contain many different kinds ofinformation. The nameplates of Saudi Aramco motors and generators should include all theinformation that is required by NEMA MG-1 and IEC 34-1 and the additional information that isrequired by SAES-P-113. The following is a list of the information that NEMA MG-1 requireson machine nameplates:

• Manufacturer information (e.g., name, serial number, and type designation).

• Horsepower output or kilowatt.

• KVA output (ac generators only).

• Power factor (ac machines only).

• Frequency (ac machines only).

• Voltage.

• Rated-load amperes.

• Rated field/armature voltage and current (if applicable).

• Time rating.

• Temperature rise (or maximum ambient temperature).

• RPM at full (or rated) load.




• Number of phases (ac machines only).

• Code letter for locked rotor KVA (ac motors only).

• Winding (dc machines only).

• Insulation system designation.

• The words "Impedance or Thermally Protected" (if applicable).

A brief discussion of nameplate items will be provided. Because Electrical Engineers should havea working knowledge of the electrical engineering principles that are associated with motors andgenerators, fundamental ratings, such as voltage, current, and frequency, will not be covered.

The time rating and temperature rise are nameplate values that describe the ability of machineinsulation and cooling medium to prevent the machine from overheating at full load conditions forextended periods of time. The time rating (usually given in minutes) is the time that it takes forthe machine to exceed maximum temperature values under full load and overload conditions. Thetemperature rise is a maximum temperature value above the ambient temperature of the machine.The temperature rise corresponds to an insulation system class designation with the machineoperating at the machine rating at the base speed. For machine applications that require anoverload capability, a service factor of > 1.0 is used. The service factor is a multiplier that takesinto account overload conditions.

The nameplate of most ac motors must be marked with a locked-rotor kVA "code." The code isa letter designator that corresponds to a locked-rotor kVA value per horsepower. A locked-rotorkVA value per horsepower table is provided in Work Aid 1.

Motor and generator insulation classes are divided into four classes that correspond to the thermalendurance of the machine for temperature rating purposes. The four insulation system classdesignators are A, B, F, and H. The minimum requirements for insulation classes are provided inWork Aid 1.

When a small motor is equipped with a thermal protector, the words "thermally protected" areprovided on the nameplate. The words "impedance protected" are provided on the nameplate ofsmall motors that are manufactured with sufficient impedance to withstand the overheating thatoccurs when a motor is overloaded or fails to start.




The following additional data are required by SAES-P-113 and can be supplied on a separatenameplate(s):

• Buyer's purchase order number.

• Year of manufacture.

• Manufacturer's location.

• Manufacturer's order reference number.

• Anti-friction bearing number and manufacturer.

• Class, group, and division (explosion-proof motors only).

• Rotor weight.

• Total weight of motor.

Saudi Aramco also requires that a separate nameplate be supplied to show the direction of motorrotation. The direction of rotation should be indicated by an arrow, and the nameplate should belocated on the non-drive end of the motor. Nameplate(s) and rotation arrows must be made from300 series stainless steel or monel, must be securely fastened to the motor by pins of similarmaterial, and must be located for easy visibility. The entries on the nameplates must be marked byetching, engraving, or other permanent method of marking.

To verify that a motor that is installed in a hazardous area is permitted in that area, additionalinformation must be included on the nameplate. All the information that is required by NEMAMG-1 must be on the nameplate, plus the following additional information:

• Class, division, and/or group of hazardous atmosphere type for which the machineis approved.

• Type of protection that is provided.

• Temperature class for which the motor is approved.

• Maximum exposed temperature of the machine.




EVALUATING MOTOR AND GENERATOR INSTALLATION AND TESTING

The process of determining whether machines should be commissioned is to verify that all of theelectrical inspections and tests have been properly performed and to verify that the test resultsmeet the specifications that are designated by the applicable Saudi Aramco and industry standards.

Installation inspections are performed to verify that proper machine installation materials are used,that installation specifications and parameters are met, and that proper installation procedures arefollowed. The installation inspection is conducted to ensure that machines will function properlyonce they are installed. Electrical tests are performed to check the ability of machines to functionunder all operating conditions and loads. Installation tests should detect shipping or installationdamage, gross manufacturing defects, or errors in workmanship or installation. The SaudiAramco Pre-Commissioning Form, P-019, NEMA Frame, Form Wound Induction andSynchronous Motors, contains guidance on the items that should be inspected, checked, andtested during the commissioning of rotating machine installations. Form P-019 is provided inWork Aid 2.

The proper evaluation of inspection and testing data during the commissioning process canmaximize the operating time of equipment installations through a determination of trends towardsfailure. Failure prediction can drastically reduce equipment down-time; if a failure is predicted,operational changes can be made, maintenance can be performed, or equipment that is failing canbe replaced in a controlled manner. If a problem is corrected before it causes damage, operatingcosts will be lower because a malfunction can cause associated (or nearby) equipment damage anddisruption of service, or the problem can activate emergency repair crews. A failure in any one ofthe many inspections, checks, or tests that are performed on rotating machines during theinstallation and testing evaluation is sufficient to prevent the machine from being commissioned.

Visual Inspection

Visual inspections are used to assess the physical condition of machines during the commissioningprocess. A visual inspection is a pass/fail verification about a particular aspect of the physicalcondition or the operation of equipment. Because the criteria that are established to determinethe acceptability of the visual inspections can be subjective, the visual inspections should beperformed by an experienced Electrical Engineer. Visual inspection items for motors are listed inSaudi Aramco Pre-Commissioning Form P-019, NEMA Frame, Form Wound Induction andSynchronous Motors. Because of the manufacturing and performance similarities between motorsand generators, many of the inspection items are the same for generators as they are for motors.




Because of the large number of inspection items that are associated with rotating machines, thereare several courses of action for visual inspection failure. The course of action depends on thepart of the machine that failed the visual inspection. For example, a failure of cleanliness visualinspection can generally be corrected through cleaning the machine. A physical damage orsuitability inspection failure will probably require the replacement of the damaged machinecomponent. The following visual inspections are used to assess the condition of rotatingmachines in Saudi Aramco systems:

• Suitability

• Physical Damage

• Personnel Protective Devices

• Cleanliness

• Area Classification

Suitability

The purpose of the suitability visual inspection is to determine whether the motor is appropriatefor the application. Under normal circumstances, the suitability of the machine should bedetermined before it is placed into the system; however, a visual inspection should be performedto ensure that the motor is of the correct size and type for the installation, and that the motorclassification is consistent with the area classification of the installation site. To determine thesuitability of a motor, a visual inspection of the nameplate data should be performed andcompared to the electrical system single line diagram.

Physical Damage

Physical damage to a motor can lead to motor failure during critical system operations. Becausemotors support fluid flow (e.g., lubricating or cooling oil), a motor failure can lead to catastrophicequipment failure, fire, personal injury, or death. Any physical damage to a motor or missingparts that were noted during the physical damage visual inspection requires the immediatereplacement of the damaged or missing component. The most obvious and common forms ofphysical damage are cracks, dents, missing or broken pieces, and bent ventilation openings. Thepurpose of the physical damage inspection is to identify whether corrective maintenance orcomponent replacement is necessary. Motors that show any form of physical damage, no matterhow small, should be determined to have failed the physical damage inspection.




Personnel Protective Devices

Because of both its mass and its speed, rotating equipment is dangerous to personnel who workaround it. The electric power that is required to operate rotating equipment also makes itdangerous. To prevent injury to personnel, all rotating equipment is required to be installed withpersonnel protective devices. Such devices consist of screens, guards, and other items thatprotect operations and maintenance personnel from contacting rotating surfaces and hazardousvoltage potentials. The purpose of the personnel protective devices inspection is to ensure thatthe devices are properly installed prior to commissioning.

Cleanliness

The purpose of the cleanliness visual inspection is to ensure the proper operation of the machineover the maximum operating life of the machine. The accumulation of dirt over a period of timewill impede the proper operation of the machine (e.g., rotor and brushes) and will reduce thedielectric strength of the insulation. Dust and dirt will also create additional ground paths thatreduce the efficiency of the motor and cause overheating and long-term damage. Theaccumulation of heavy amounts of dust and dirt should be cleaned away from the machine duringmaintenance cycles. Motors that are installed in extremely dirty, dusty, or humid areas may haveto be cleaned more often than once during each maintenance cycle.

Area Classification

Because industrial settings contain various hazardous areas, it is important that the machine that isinstalled has the correct enclosure and cooling for the area classification. The purpose of the areaclassification visual inspection is to verify that a motor that is installed in a hazardous area ispermitted in that area. During the commissioning process, the Electrical Engineer should verifythat the enclosure classification information that is included on the machine nameplate (e.g., Exd)matches the equipment prints, drawings, and the actual motor installation conditions.

Mechanical Inspection

A mechanical inspection is used to assess the ability of the machine to physically perform themechanical movements that are necessary for proper operation. Mechanical inspection items arelisted in Saudi Aramco Pre-Commissioning Form P-019, NEMA Frame, Form Wound Inductionand Synchronous Motors, which is provided in Work Aid 2. Because there are severalmechanical inspection items that are associated with motors, there are a number of correctiveactions for a mechanical inspection failure. The corrective action depends on the part of themachine that failed the inspection. For example, a mounting bolt inspection failure can usually becorrected through adjustment of the bolts with a torque wrench.




The general mechanical inspections and tests that are performed on motors that are installed inSaudi Aramco systems are as follows:

• Mounting Bolts

• Motor Alignment

• Shaft Rotation

• Lubrication

• Rotor to Stator Air Gap Alignment

Mounting Bolts

The purpose of a mounting bolt inspection is to verify that the motor's mounting bolts are securelyfastened. The bolts and frame mounts must be capable of preventing the motor from comingloose during mechanical failure or electrical fault conditions. To perform the mounting boltcheck, the manufacturer's technical manual is consulted for the proper bolt torque value. Atorque wrench is then used to determine the amount of torque at the bolt. Improper torque valuesare immediately corrected.

Motor Alignment

Motors are installed in facilities to perform a function. As the motor shaft turns, the mechanicalwork is transferred to another piece of equipment (e.g., pump or compressor). The purpose of themotor alignment mechanical inspection is to ensure that the shaft of the motor is correctly alignedand coupled to the driven equipment.

Shaft Rotation

The shaft rotation is generally performed in conjunction with the motor alignment visualinspection. The purpose of the shaft rotation mechanical inspection is to ensure that the shaft ofthe motor rotates freely and that there are no visual or audible indications of scraping or bindingas the shaft turns. For ac induction motors that do not have slip rings or a commutator, the shaftrotation mechanical inspection is performed by rotating the shaft by hand and inspecting the shaftas it rotates. For dc machines and ac machines with slip rings, the Electrical Engineer should alsoinspect the brushes and brush holders during the shaft rotation mechanical inspection.




Lubrication

The lubrication system visual inspection should be performed in conjunction with the cleanlinessvisual inspection. The purpose of the lubrication visual inspection is to ensure that the motorbearings will be provided with proper lubrication upon energization of the motor. The items thatare inspected in the performance of the lubrication system visual inspection are dependent on thetype of lubrication system with which the motor is equipped. Motors can be equipped with theeither self-contained or external lubrication systems.

Most motors are equipped with self-contained lubrication systems. These systems use grease oroil to provide the required lubrication to the motor bearings. The lubrication system visualinspection that is performed on a self-contained lubrication system should consist of a visualinspection of the bearing cavity or the oil reservoir (as applicable). Initial data records should beinspected to determine that the correct lubricating medium was used.

Large motors are usually equipped with external lubrication systems. These systems use an oilpump and associated oil pipes to provide the motor bearings with a continuous supply oflubrication. External lubrication systems usually contain a pump, an oil sump, an oil filter,monitoring equipment, and the associated oil system pipes. The external lubrication system visualinspection should consist of a visual inspection of the bearing cavity or the oil reservoir (asapplicable), the oil sump level, the oil system piping, and the components. An oil sample from theoil sump should be drawn and analyzed. Initial data records should be inspected to determine thatthe correct lubricating medium was used.

Rotor to Stator Air Gap Alignment

The air gap between the rotor and the stator is checked. This air gap must be uniform to preventmechanical noise, vibration, and misalignment.

Electrical Inspection and Test

During the commissioning process, electrical inspections and tests are performed to check theability of motors to operate for a reasonable future period of time under all operating conditionsand loads. Acceptance or installation tests will usually detect shipping or installation damage andgross defects or errors in workmanship in equipment construction. Once the installation andinspection data have been recorded and assembled, a methodical and consistent program ofperiodic data collection and evaluation should be established. As each new maintenance item,test, system addition, or system reconfiguration occurs, new inspections and data records will berequired and should be added to the existing data on file.




Because an electrical inspection or test failure can be caused by a design flaw, a constructionerror, equipment age, or operational misuse, some kind of troubleshooting or maintenance activityshould be performed on the faulty equipment. For example, an insulation resistance (megger) testfailure can usually be rectified by cleaning the interior of the machine to remove dirt and carbondust build-up. Some electrical inspection or test failures are not repairable, and they will requirethe replacement of the equipment before the motor can be commissioned. For example, a windingresistance test failure usually indicates a damaged or an improperly wound motor winding.

The following electrical inspections, checks, and tests are performed on motors:

• Winding Resistance

• Insulation Resistance

• Dc High-Pot

• Miscellaneous Electrical Tests

• Energization Tests

Winding Resistance

The purpose of the motor winding resistance test is to verify that the winding resistance of allmotor windings (e.g., rotor, stator, and exciter) are in accordance with the manufacturer's listedvalues. The motor winding resistance test may also identify loose connections or improperterminations within the motor enclosure.

To conduct the motor winding resistance test, the winding under test is electrically disconnectedfrom the motor. Once the winding under test is electrically removed from the system, the leads ofa digital, low-resistance ohmmeter are placed across each isolated winding and measurements aretaken. A digital, low-resistance ohmmeter can deliver enough power to the contacts to makeaccurate readings that have more validity than those readings that can be obtained through the useof an ordinary multimeter. The motor winding resistance is recorded on a test data sheet or onthe Saudi Aramco Pre-Commissioning form, P-019, NEMA Frame, Form Wound Induction andSynchronous Motors. Technical data to evaluate the results of the motor winding resistance testcan be found in the motor manufacturer's technical manual.

Insulation Resistance

The purpose of the insulation resistance (megger) test is to directly measure the insulationresistance of the motor components. The megger produces a high potential that is applied fromthe motor windings and other insulated parts to ground. The leakage current that is detectedresults in a megger meter readout of insulation resistance in megohms.




To conduct the insulation resistance megger test, each winding of a motor is electricallydisconnected from the others if possible. Once the windings are disconnected, the megger isconnected between each motor winding and ground, and the megger is operated. Insulationresistance megger tests must be conducted for each winding of the machine. Some largersynchronous motors contain digital equipment in the field winding circuits. Because the voltagepotentials that are generated during the megger test can damage any connected electronicequipment, megger tests must not be performed on electronic equipment. A bearing insulationresistance test is also performed on motors that have insulated bearings. The insulation resistancevalues are recorded on a test data sheet or on Saudi Aramco Pre-Commissioning form P-019,NEMA Frame, Form Wound Induction and Synchronous Motors, in the recorded test datasection.

For Saudi Aramco motor installations, megger readings must be corrected to 50oC. Temperaturecorrection of megger readings is performed by multiplying the megger value by an insulationresistance temperature coefficient (Kt). A table of various values of Kt is provided in Work Aid2.

During the commissioning process, the Electrical Engineer should evaluate the insulationresistance (megger) test values to ensure that the insulation resistance values that were recordedare greater than the manufacturer's minimum values. Minimum values of insulation resistancereadings are provided in Work Aid 2. Any value of insulation resistance that is less than theminimum specification should be investigated by the Electrical Engineer who performs the testdata evaluation.

The ratio of two time-resistance readings (such as a 60-second reading that is divided by a 30-second reading) is called a dielectric absorption ratio. The dielectric absorption ratio is useful inrecording information about the insulation. If the ratio is a ten-minute reading that is divided by aone-minute reading, the value is called the polarization index.

Because constant cranking is required for hand-cranked megger instruments, it is easier to run thetest for only 60 seconds and take the first reading at 30 seconds. When a power-operated meggerinstrument is used, the results of running the test for a full ten minutes and taking readings at oneminute and at ten minutes will give the polarization index. An explanation of the evaluation of thedielectric absorption ratio is provided in Work Aid 2.




Dc High-Pot

The dc high potential (high-pot) test is performed to provide positive proof that a motor'sinsulation has sufficient voltage strength to ride out overvoltage surges. The dc high-pot testshould be done prior to the initial energization of the motor and after satisfactory megohmmetertesting. The dc high-pot testing technique for motors involves the measurement of increased dcvoltage that is applied to the motor under test. The value of the leakage current is tracked as thetest voltage is increased through several steps, and this value becomes a criterion of the conditionof the motor insulation.

The Electrical Engineer should evaluate the dc high-pot test leakage current test data to ensurethat the motor high-pot test data meet the minimum requirements of a successful test. To conductthe dc high-pot test, a test set is connected between the motor phase leads and ground. After thetest set is connected, the initial test voltage, which is equal to 33% of the maximum test voltage,is applied to the motor. The maximum dc test voltage for a motor is calculated through use of thefollowing formula: Maximum Voltage = 75% (1.7(2 x Rated Voltage + 1 kV)). The initial testvoltage is held for ten minutes, and the leakage current, as read on the test set, is monitored. Thevalue of leakage current is recorded at the end of each one minute interval. The polarizationindex is calculated from this test data through division of the leakage current after one minute bythe leakage current that is obtained after ten minutes.

When the first ten minutes of the test is complete, the test voltage should be raised from the initialvalue of 33% to the maximum value in ten equal steps. After each step increase in voltage, thevoltage should be held at the new level for a period of one minute, and the leakage current shouldbe recorded at the end of each minute.

The results of a high-pot test are not compared to a specific value to determine whether theresults are acceptable. Instead, the results of a high-pot test are analyzed for trends that indicatewhether the insulation has sufficient strength to ride out overvoltage surges. A polarization indexvalue of less than two or dc high-pot test data curves that indicate a steady increase in leakagecurrent over the duration of the test should be investigated by the Electrical Engineer whoperforms the test data evaluation.

Figure 2 shows a graphic display of the typical results of high-pot tests for both good and badinsulation. The graph that is shown in Figure 2A is for the first ten minutes of a high-pot test.The curve that represents good insulation shows, over the first one-minute interval, a steep rise inleakage current that is followed by a steady decrease in the value of leakage current over theremainder of the ten-minute interval. The curve that represents bad insulation shows a steadyincrease in the value of leakage current throughout the ten-minute interval. Such a curveindicates unsatisfactory insulation, and the high-pot test should be stopped.




The graph that is shown in Figure 2B is for the last ten minutes of the high-pot test. The curvethat represents good insulation shows a slow, steady increase in the value of leakage current asthe test voltage is raised from 33% to 100%. The curve that represents bad insulation shows asharp upturn or knee when the test voltage is increased to the point at which the insulation startsto break down. A knee in the leakage current curve indicates unsatisfactory insulation, and thehigh-pot test should be stopped.

Figure 2: Typical Results of High-Pot Tests




Miscellaneous Electrical Tests

In addition to the more familiar electrical tests, such as insulation resistance, Electrical Engineerswho are commissioning motors should be familiar with miscellaneous motor tests. Two of themiscellaneous electrical tests that are conducted on motors are the air gap test and the phaserotation test.

Air Gap - The radial air gap should be checked on motors that are rated at 5000 hp orabove to ensure that the air gap is uniform and that it is within the manufacturer'sspecifications. An unequal air gap can cause unequal currents in the stator windings thatwill result in unequal heating of the stator windings. The unequal currents in the statorwindings also can result in an unbalanced magnetic pull between the stator and the rotor,and an unbalanced magnetic pull increases the possibility of contact between the stator andthe rotor while the motor is in operation. Such contact can result in catastrophic damageto the motor.

The radial air gap should be checked at eight different points around the circumference ofthe stator. The radial air gap is checked through insertion of a feeler gauge between therotor and the stator windings of a motor. The feeler gauge size that just bridges the gapbetween the rotor winding and the stator winding is the size of the radial air gap.Minimum acceptable values for radial air gap are provided in Work Aid 2.

Phase Rotation Test - Phase rotation tests are performed to ensure that the motor willrotate in the correct direction and that the motor leads are properly marked to coincidewith the power system leads. If the motor rotates in the wrong direction, damage canoccur to the connected load.

The phase rotation test is the final pre-energization requirement because this test actuallyis performed through energization of the motor. The phase rotation test consists of avisual verification that the motor leads are properly marked to coincide with the powersystem leads and that the motor shaft rotates in the correct direction.

The phase rotation test is performed through a momentary application of power to themotor while the load is disconnected and through observation of the direction of shaftrotation. If the shaft rotates in the wrong direction, the connection between two of themotor leads and two of the power system leads must be switched. After the leads areswitched, the phase rotation test should be repeated to verify that the direction of shaftrotation has been corrected. After the verification is complete, the motor lead markersalso should be switched.




Energization Tests

Energization tests are performed on a motor during the commissioning process to verify that themotor installation is free from defects, to verify that the motor operates within its design limits,and to establish baseline motor operational data. Before energization tests are performed on amotor, all of the discrepancies that were identified during the pre-energization portion of thecommissioning process must be corrected. The two types of energization tests that are performedon motors during the commissioning process are the no load run test and the load run test.

No Load Run Test - For an electric motor, a no load run test consists of themeasurement of various operational parameters of the motor while the motor is inoperation but before the motor is connected to the load that it was installed to drive. Theno load run test is performed prior to connection of the motor to its load to ensure that theinformation that is obtained from the test only applies to the motor. If the information thatis obtained from the test is unsatisfactory, and if the test is conducted with the motorconnected to the load, the cause of the unsatisfactory condition would be more difficult todetermine. Also, if a problem does exist with the motor, performance of the test with themotor connected to the load would be more likely to aggravate the problem.

Before a no load run test is performed on a motor that is equipped with space heaters, thespace heaters must be turned on and the space heater current must be measured. Thespace heater current is measured to verify that the space heaters properly operate (e.g.,that there are no burned-out units or loose connections). To ensure that condensationdoes not form inside of the motor when the motor cools off after the test, the spaceheaters must be operational before the no load run test is performed.

The operational parameters that are measured during a no load run test vary with the typeof motor to be tested. No load run test evaluation information is provided in Work Aid 2.For induction and synchronous motors, the following operational parameters should bemonitored during a no load run test:

• Phase current balance

• Voltage balance

• Vibration level

• RTD readings for bearings and stator windings

For synchronous motors, the following additional operational parameters should bemonitored during a no load run test:

• Field current

• Power factor and kVAR control




Load Run Test - For an electric motor, a load run test consists of the measurement ofvarious operational parameters of the motor while the motor is in operation and while it isconnected to the load that it was installed to drive. The load run test should be conductedafter all of the necessary repairs/adjustments that were identified during the no load runtest have been completed. The operational parameters that are measured during a loadrun test vary with the type of motor to be tested. Load run test evaluation information isprovided in Work Aid 2. For induction and synchronous motors, the followingoperational parameters should be monitored during a load run test:

• Motor alignment

• Phase current balance

• Voltage balance

• Vibration level

• RTD readings for bearings and stator windings

• Voltage dip on start

• Acceleration time

• Test duration

The following additional operational parameters should be monitored during a load runtest for a synchronous motor:

• Field current

• Power factor and kVAR control




WORK AID 1: REFERENCES FOR EVALUATING MOTORS AND GENERATORSUPON RECEIPT

The minimum mandatory requirements for the procurement and installation of induction andsynchronous motors and generators that are installed in Saudi Aramco industrial facilities aredefined in SAES-P-113.

The minimum mandatory technical requirements for 460 V and below, 60 Hz, NEMA Frameinduction motors that are rated from 0.746 to 185 KW (1 hp through 250 hp) that are installed inSaudi Aramco industrial facilities are defined in 17-SAMSS-503. 17-SAMSS-503 does not coversubmersible motors, overhead crane motors, and valve-operator motors.

The minimum mandatory technical requirements for form-wound squirrel-cage induction andbrushless salient-pole synchronous motors that are installed in Saudi Aramco industrial facilitiesare defined in 17-SAMSS-502. 17-SAMSS-502 covers form-wound squirrel-cage induction andbrushless salient-pole synchronous motors that are rated 150 kW (200 hp) and larger, at operatingvoltages of 2300 volts and above, three-phase, at both 50 and 60-hertz.

Unless stated otherwise, the information in this Work Aid contains combined excerpts fromaccepted industry practices and from the following resources:

• SAES-P-113, Motors and Generators

• 17-SAMSS-503, NEMA Frame Motors

• 17-SAMSS-502, Form Wound Induction and Synchronous Motors

• 17-SAMSS-510, Synchronous Generators

• GI-2.710

• NEMA MG-1

Work Aid 1A: Motor and Generator Technical and Construction Requirements

Figure 4 shows Saudi Aramco motor and generator material and installation requirements(excerpted from SAES-P-113).




GeneralInstallation

Motors for non-industrial facilities must meet the requirements of NEMAMG 1.

Requirements Motors and generators must be installed in accordance with ANSI/NFPA 70(NEC).Cable, conduit and/or other connections must not electrically bridge insulatedbearings.Auxiliary instrumentation must comply with SAES-J-604.Generators that are rated 125 kVA (100 kW) through 1250 kVA (1000 kW)must comply with 17-SAMSS-510.Generators that are rated 2500 kVA and above must have surge protectionrated in accordance with 17-SAMSS-502.Motors that are rated 0.746 kW (1 hp) and above must comply with17-SAMSS-502 or 17-SAMSS-503.Motors for belt-driven fin-fans must be designed for vertical operation.

FractionalKilowatt

Motors that are rated less than 0.746 kW (1 hp) must comply with NEMAMG 1.

(Horsepower)Motors

Motors that are rated less than 0.746 kW (1 hp) must comply with thefollowing additional requirements:

a) Motors for outdoor installation must be of the totally enclosed type.b) Motors for indoor installation must be of the drip-proof guarded type.c) The insulation system must be Class B minimum.d) Enclosures and terminal housings must be metallic.e) Single Phase Motors must be provided with a built-in thermal

protective device.f) Fans must be metallic or reinforced fiberglass, and must be designed

for dual rotation.High VoltageApplicationInstallation

Motors that are rated for operating speeds of 3600 RPM must not exceed3000 kW (4000 hp) without written approval of the Saudi Aramco ChiefEngineer, Dhahran.

Requirements Surge tests of all 13.2 kV motors are required (refer to 17-SAMSS-502).Motors that are rated 4000 kW (5360 hp) must have pedestal bearings.

Figure 4: Saudi Aramco Motor and Generator Materialand Installation Requirements (from SAES-P-113)




Figure 5 shows motor construction requirements for Saudi Aramco installations.

Stator The stator frame should be of fabricated steel construction, with sufficientstrength and rigidity to withstand the stresses to which the stator may besubjected in handling, transport, or due to short-circuit or other forces whenin service.

Rotor Induction motors should have a cylindrical rotor of the squirrel-cage type.Synchronous motors are available in cylindrical rotors or salient pole rotors.Cylindrical synchronous motors are used in speeds in excess of 1800 rpm.Salient pole rotors come in two types:

• The laminated salient pole rotor with a cage damper winding in eachpole face for starting.

• The solid pole rotor with solid bolted pole shoes.The solid pole rotor is the preferred type of synchronous salient pole rotor forSaudi Aramco installations.

Figure 5: Motor Construction Technical Requirements

The critical speeds of motors depend on the type of shaft that is used for the motor construction.Critical speeds of motors that are used in Saudi Aramco installations are shown in Figure 6.

First LateralCritical Speed

Second LateralCritical Speed

Rigid Shaft 115% rated motor rpm Not within ±10% of 2 timesrated motor rpm

Flexible Shaft 65 to 85% rated motor speed Not within ±10% of 2 timesrated motor rpm

Figure 6: Critical Speeds of Motors




Bearing types are shown in Figure 7.

Motor Size Bearing Type< 15 hp (11 kW)� 15 hp (11 kW)> 200 hp (150 kW) *

200 or 300 series ball bearings300 series ball bearingsSleeve bearings

* Horizontal Motors

Figure 7: Bearing Types

Bearing lubricants are shown in Figure 8.

Bearing Type LubricationAnti-friction

SleeveOil or Grease

Oil

Figure 8: Bearing Lubricants

Method of Bearing Lubrication

Sleeve bearing lubrication methods are shown in Figure 9.

Shaft Journal Velocity m/S Type of LubricantBelow 1111 and above

Uncooled ring or disc oil lubricationCirculated feed oil lubrication

Figure 9: Sleeve Bearing Lubrication




Figure 10 shows motor and generator bearing technical requirements.

GeneralBearingConstruction

Ball bearings should be of the re-greasable shielded type, furnished withoutgrease fittings, but equipped with plugs in the tapped holes that are normallyprovided for such fittings.Relief holes or drain plugs that are located 180o from the grease point shouldbe provided.Pre-lubricated sealed anti-friction bearings are not acceptable.

BearingHousingProtection

Horizontal motors that are rated <3730 kW (5000 hp) must have the bearingshoused in the endbells of the motor.

Horizontal motors that are rated 3730 kW (5000 hp) and larger must beprovided with pedestal bearings that are supported by the motor baseplate.The bearing housing for horizontal motors with oil-lubricated bearings must beequipped with labyrinth type end seals and deflectors where the shaft passesthrough the housing.Vertical motors with oil or grease-lubricated bearings must be provided with apositive shaft seal on top and bottom bearings.

BearingInsulation

Horizontal motors that are rated 375 kW (500 hp) and larger should havebearings that are electrically insulated from the motor frame or baseplate.A removable test link should be provided for the drive end bearing.Vertical motors that are rated 375 kW (500 hp) and larger should have anelectrically insulated top bearing.

Figure 10: Motor and Generator Bearing Technical Requirements

Figure 11 shows motor and generator mechanical noise and vibration monitoring requirements.

MechanicalNoise

The mechanical noise sound pressure level at one meter should not exceed 90dB.

VibrationMonitoring

Vibration monitoring equipment should not be used for motors below 185 kW(250 hp).For horizontal motors that are rated between 750 kW (10000 hp) and 3000kW (4000 hp), one seismic detector must be mounted horizontally at eachbearing.For horizontal motors that are rated 3001 kW (4001 hp) and above, twoproximity detectors must be mounted 90o apart at each bearing.For vertical motors, seismic type vibration detectors must be mounted 90o

apart around the circumference of the top bearing housing.

Figure 11: Mechanical Noise and Vibration Monitoring




Figure 12 shows motor enclosure protection and specification requirements. Motor main andauxiliary equipment boxes should meet or exceed the main motor enclosure requirements.

Protection All Saudi Aramco motor enclosures must be protected to a level that is equalto the IEC level designation IP44.

TEFC Totally Enclosed Fan-Cooled (TEFC) enclosures are allowed on motors thatare rated less than 11,000 kW (15,000 hp).Permitted in zone 1, zone 2, and unclassified locations.

CACA Totally Enclosed Air to Air-Cooled (CACA) enclosures are required for useon all induction motors and for salient pole synchronous motors that are ratedup to 11,000 kW (15,000 hp) when the motor's temperature rise exceeds theallowable temperature rise for class B insulation.CACA enclosures are required for use on induction motors that are ratedgreater than 11,000 kW (15,000 hp).CACA enclosures are required for use on synchronous motors where thecleaning cost over the life of the machine plus the capital cost of an openmotor would be more than the cost of the CACA enclosure.CACA enclosures are permitted in zone 1, zone 2, and unclassified areas.

WPII Weather Protected (WPII) enclosures must be specified for synchronousmotors that are rated above 11,000 kW (15,000 hp) where the lifetime motorcleaning costs plus motor capital costs are less than the capital cost of aCACA motor.WPII enclosures are permitted in zone 2 and unclassified locations.

GroundingRequirements

Motors up to 150 kW (200 hp) require a grounding stud.

Motors at or above 150 kW (200 hp) require a grounding pad

Figure 12: Motor Enclosure Protection and Specification Requirements.

For motors that are installed in classified environments, special enclosure requirements arenecessary. Class I, Division 1 and 2 locations with Group D hazards are the common classifiedenvironments that are found in Saudi Aramco installations.

For a Division 1 area, the motor enclosure must be explosion-proof (Exd). The totally enclosedflameproof motor is preferred for motor sizes up to about 500 kW (700 hp) because of the TEFCruggedness and simplicity. For larger motor sizes, the normal practice is to avoid Division 1locations because of the cost of the enclosures.




For a Division 2 area, the motor enclosure must be non-sparking (Exn). The type of protection"n" is such that during normal operation, the motor is not capable of causing ignition, and a faultthat is capable of causing ignition is not likely to occur; therefore, any type of enclosure thatprevents sparks can be utilized.

If the motor insulation exceeds the limits of class B insulation, a heat exchanger must be installed.Figure 13 shows the maximum allowable insulation temperature for each motor insulation class.

Motor InsulationClass

Maximum AllowableInsulation Temperature

in oCBFH

130155180

Figure 13: Maximum Allowable Insulation Temperature

Figure 14 shows motor enclosure cooling requirements.

MotorCooling

The cooling of all motor components and lubricating oil (if required) shouldbe by air. Liquid cooling is not acceptable.Where totally-enclosed machines utilize heat exchangers, closed-air circuit-air cooled (CACA) exchangers must be provided and mounted on the motor.Top-mounted heat exchanger assemblies must have flanges that extenddownward to overlap the motor enclosure on all sides by a minimum of 10mm (0.4 in).When air/air heat exchangers require auxiliary fan cooling, shaft-mountedcooling fan or fans should be provided.Auxiliary motor-driven fans are not allowed for Saudi Aramco installations.

Figure 14: Motor Enclosure Cooling Requirements




Figure 15 shows Saudi Aramco nameplate requirements.

NameplateConstruction

The nameplate(s)/rotation arrows must be 300 series stainless steel or monel.

The nameplate(s)/rotation arrows must be securely fastened by pins of 300series stainless steel, monel, or similar material.The nameplate(s)/rotation arrows must be located for easy visibility.Entries must be marked by etching, engraving, or by another permanentmethod of marking.

NameplateInformation

The following is the minimum information that is required to be on machinenameplates:

• Manufacturer's name, serial number or date code, and suitableidentification

• Horsepower output or kilowatt rating• Time rating• Temperature rise• RPM at rated load• Frequency• Number of phases• Voltage• Rated-load amperes• Code letter for kVA• Buyer's purchase order number• Year of manufacture• Manufacturer's location• Manufacturer's order reference number• Anti-friction bearing number and manufacturer class, group, and

division (explosion-proof motors, only)The following is a continuation of the minimum information that is requiredto be on motor nameplates:

• Maximum ambient temperature• Insulation system designation• Rotor weight• Total weight of motor• Direction of rotation arrow

Figure 15: Nameplate Construction and Minimum Information Requirements




Figure 16 shows Saudi Aramco NEMA Frame induction motor technical requirements (excerptedfrom 17-SAMSS-503) for motors that are rated less than 0.746 KW (1 hp).

GeneralRequirements

Motors must comply with NEMA MG-1, 1987 Rev.1, must be suitable forchemical/other severe duty applications.Motors for outdoor installation must be totally enclosed type.Motors for indoor installation must be of the drip-proof guarded type.The insulation system of the motor must be class B minimum.Enclosures and terminal housing must be cast iron or steel.Single phase motors must be provided with a built-in thermal protectiondevice.Fans must be either metallic or high density, fiber filled, conductivepolypropylene or phenolic.A corrosion-resistant grounding stud or pad must be provided in theterminal housing box.

Figure 16: NEMA Frame Induction Motor Technical Requirementsfor Motors that are Rated Less Than 0.746 KW (from 17-SAMSS-503)




Work Aid 1B: Motor and Generator Winding, Wiring, and Space Heater Requirements

Figure 17 shows motor and generator winding requirements.

StatorWinding

The stator insulation system, including the leads, must consist of low-hygroscopic materials.The stator insulation system must have Class F insulation.The stator windings must be treated to withstand tropical conditions and thecorrosive effects of industrial sulfurous atmospheres.Stator temperature must be monitored as follows:

• Motors that are rated 150 kW (200 hp) up to but not including 1300kW (1750 hp) must have one RTD per phase.

• Motors that are rated 1300 kW (1750 hp) through 7500 kW (10,000hp) must have two RTD's per phase.

• Motors that are rated above 7500 kW (10,000 hp) must have threeRTD's per phase.

• The hottest reading RTD must be identified by the vendor duringfactory testing.

RotorWindings

The rotor windings of induction machines must be of the cage type andformed from copper, copper alloy, or aluminum bar.The rotor body of synchronous machines must be of the salient-pole typewith the windings of insulated copper wire or strip that are treated towithstand tropical conditions.

AdditionalRotorConstruction

In addition to induction motor rotors, salient-pole rotors of synchronousmotors may incorporate a copper starting cage to meet a desired torquecharacteristic.

Requirements On squirrel-cage rotors, end-ring connections must be of high mechanicalstrength.

AdditionalRotor

Filler metals that are used should be resistant to attack by corrosivesulfurous gases.

ConstructionRequirements

Copper alloy rotor construction should conform to American WeldingSociety AWS A5.8 and contain a minimum 40% silver.Copper-phosphorous bronze type fillers are technically unacceptable.The motor insulation system, including the leads, must consist of low-hygroscopic materials.The rotor insulation system must have Class F insulation.

Figure 17: Motor and Generator Winding Construction Requirements




Figure 18 shows wiring and grounding requirements for Saudi Aramco motor and generatorinstallations.

Control and Wiring for auxiliary equipment must be moisture and heat resistant.Supply Leads Conductors must be made of copper and rated in accordance with the NEC

for operation at 50oC ambient temperature.Minimum conductor size must be stranded 2.5 mm sq (No. 14 AWG).Conductors must be clearly and permanently identified with sleeve type PVCwire markers.All conductors that are passing through an internal baffle or partition that iswithin the motor enclosure must be protected by a bushing.

GroundingConnections

Ground connections must accommodate the following minimum size ofgrounding cable:

Motor Rating Cable Size

kW (hp) mm2 (AWG/MCM)185 < 370 (250 < 500) 70 (2/0)370 < 3360 (500 < 4500) 120 (4/0)3360 & above (4500 & above) 185 (350)

Figure 18: Wiring and Grounding Requirements

Figure 19 shows Saudi Aramco motor and generator space heater design and constructionrequirements.

Design and Heaters must be installed in all motors that are rated 2.3 kV or higher.Construction Motors that are rated less than 2.3 kV that are installed outdoors and used

only as standby motors may also require heaters. Engineering drawingsshould be consulted.Motors must be equipped with space heaters that are completely wired, withleads that are brought out to a separate terminal box.Heaters with exposed elements are prohibited.Heater nameplate voltage must be twice the supply voltage that is indicatedon the Data Schedule.Heaters must be suitable for supply voltages of 120 VAC, and they must becontrolled by auxiliary contacts in the breaker.

Figure 19: Space Heater Design and Construction Requirements




Space heaters will maintain the temperature of the motor windings at approximately 5oC (9oF)above ambient. Surface temperatures of the space heater elements must not be greater than thosesurface temperatures that are shown in Figure 20.

Area Classification Surface TemperatureClass I, Group CClass I, Group DClass II, Group EClass II, Group G

160oC (320oF)215oC (419oF)200oC (392oF)120oC (248oF)

Figure 20: Space Heater Temperature Requirements for Classified Areas

Work Aid 1C: Motor Rating Requirements

Motors for Saudi Aramco installations must be selected in accordance with the table that is shownin Figure 21.

Nom SysVoltage

NameplateVoltage Phases kW (hp) Type Notes

120 115 1 up to 0.25 (0.34) -- -208 200 1 up to 0.25 (0.34) -- 1240 230 1 up to 0.25 (0.34) -- 1208 200 3 0.18 (0.24) to 3.7 (5.0) Ind. 1240 230 3 0.18 (0.24) to 7.5 (10.0) Ind. 1480 460 3 0.18 (0.24) to 300 (400) Ind. -4160 4000 3 150 (200) to 3000 (4000) Ind. -4160 4000 3 500 (670) to 3000 (4000) Synch. 26900 6600 3 1000 (1340) to 6000 (8000) Ind. 313,800 13,200 3 above 1000 (1340) Ind. -13,800 13,200 3 above 10,000 (15,000) Sync. 4

(1) The 200 V rating is only for operation on 208 V system, and the 230 V rating is only for operation on 240V system (see NEMA MG 1-14.33).

(2) Only for application at operating speeds of 1200 rpm and below.(3) Above 1000 kW (1340 hp) the additional level of 6.6 kV is permitted. The use of a 6.6 kV motor plus

unit transformer must be compared with a 13.2 kV motor on the basis of cost.(4) Synchronous motors smaller than 10 000 kW (15 000 hp) are to be used only for operating speeds of 1200

rpm and below.(5) Direct replacement of existing 2300 V Squirrel Cage Induction Motors is permitted. New installations of

2300 V Squirrel Cage Induction Motors with ratings from 185 kW (250 hp) to 1500 kW (2000 hp) arepermitted if they are part of a 2400 V system expansion or addition which has been approved.

Figure 21: Motor Selection Table (from SAES-P-113)




Figure 22 shows a table of locked-rotor kVA "codes." The letter designators correspond to kVAper horsepower for ac motors.

Letter Designation kVA per hp Letter Designation kVA per hpA 0 - 3.15 K 8.0 - 9.0B 3.15 - 3.55 L 9.0 - 10.0C 3.55 - 4.0 M 10.0 - 11.2D 4.0 - 4.5 N 11.2 - 12.5E 4.5 - 5.0 P 12.5 - 14.0F 5.0 - 5.6 R 14.0 - 16.0G 5.6 - 6.3 S 16.0 - 18.0H 6.3 - 7.1 T 18.0 - 20.0J 7.1 - 8.0 U 20.0 - 22.4

V 22.4 - and up

Figure 22: Ac Motor Locked-Rotor KVA per Horsepower (From NEMA MG-1)

Work Aid 1D: Data Schedules

Figure 23 shows the data schedule from 17-SAMSS-503 that is used to order NEMA Framemotors.




DATA SCHEDULEFOR 17-SAMSS-503

NEMA FRAME MOTORS

----------------------------------------------------- INFORMATION SUPPLIED BY BUYER

1. Buyer's Quotation Request/Purchase Order No. _____________________2. Buyer's B.I./J.O. No. ____________________________________________3. Buyer's Line Item No. ____________________________________________4. Driven Equipment: ________________________________________________5. Motor Rating: KW ( hp)6. Synchronous Speed: _____________________ RPM7. NEMA Torque Design: ( ) "B"; ( ) Other (specify) ______________8. Voltage ; Frequency 60 Hz; Phase ;9. Rotation Direction (Facing Motor Non-Drive End Opposite Shaft Extension)

(Check one): ( ) clockwise; ( ) counterclockwise10. ( ) Horizontal; ( )Vertical11. Enclosure: ( ) TEFC; ( ) TENV; ( ) Explosion-proof;

( ) Other (specify) __________________12. ( ) Unclassified Area; ( ) Classified Area; Class ;

Division ; Group 13. Shaft Type (Vertical Motors) ( ) Solid ( )

Other (specify) _________________14. Special Torque Requirements (if applicable)15. Main Terminal Box, Conduit Hub Size: -----------------------------------------------------

Approved: ______________ Dwg. No. NT-

Date: ______________ Revision No. ____________

Sheet 1 of 1

Figure 23: NEMA Frame Motor Data Schedule (from 17-SAMSS-503)




Figure 24 shows the data schedule from 17-SAMSS-502 that is used to order induction motors.

ATTACHMENT TO 17-SAMSS-502 (20 JUN 1995) INDUCTION MOTOR DATA SHEET - INFORMATION SUPPLIED BY BUYER

Buyer's Quote. Req./P.O. No. __________ B.I./J.O. No. ______ Line Item No. ______ Quantity _______ Driven Equip. ____________ Model ________ Ser. No. ________ Driven Eq't Data Sheet No. _________________

1. Nameplate kW ____ ( ____ hp)2. Volts _____ 3. Phases __ 4. Hz ___ 5. Synch. RPM _____6. Insul. Class ____ 7. Temp. Rise above 50 deg C by RTD _____8. Mounting: Horizontal ___ Vertical ___9. Bearing Type: Hydrodynamic ___ Anti-friction ___10. Max. Sound Pressure Level _____ dB(A)11. Drive System:

(A) Rotation Req'd by Driven Equip. Facing Motor Oppos. Dr. End:Clockwise ___ Counterclockwise ___(B) Dir. Connected___ (C) Gear___ (D) Coupling Type ____

12. Enclosure:(A) TEFC ___ (B) CACA ___(C) TEAAC ___ Tubes: Aluminum ___ Aluminum Alloy ___ Copper ___ Copper Alloy___ Stainless Steel ___(D) Explosion proof ___ Class ___ Div. ___ Group ___ Ignition Temperature ___

13. Site Conditions: (A) Onshore ___ (B) Offshore ___ (C) Dust ___ (D) CorrosiveConditions___

14. Terminal Box Sized for(A) Main motor leads: Shielded Cable Copper EPR___ XLPE___ Size_____mmsq/____AWG/MCM No./Phase___Enter from: Above__ Below__ Side__ (R/L)Conduit Type_______; Size____; Number______(B) C.T.'s for Differential Protection Yes ___ No ___(C) Surge Protection Yes ___ No ___

Figure 24: Induction Motor Data Schedule (from 17-SAMSS-502)




15. Tests(A) Performance Determination: Yes ___ No ___(B) Temperature Test: Yes ___ No ___(C) Miscellaneous Test: Yes ___ No ___(D) Surge Test: Yes ___ No ___(E) Conformance Test: Immersion ___ Spray ___(F) Partial Discharge(13.2 kV only):Yes___ No___

16. Space Heater:Voltage ____Terminal Box: Conduits:____ EANPT size:___Inch

17. Provide Sight Oil Gauge: Yes:______ NO:_______18. Vibration Detector Terminal Box: For Conduits:_____ EA

NPT size :_____ Inch19. R.T.D Terminal Box: For Conduits:________ EA

NPT Size :________ Inch20. Vendor to supply Speed-Torque and Speed-Current Curves

Yes:______ No:_______

Approved by _____________________ Date _____________ ---------------------------------------------------- PLANT NO. INDEX DRAWING NO. SH. NO.REV. NO. ---------------------------------------------------- P 1 OF 2 ----------------------------------------------------

Figure 24: Induction Motor Data Schedule (from 17-SAMSS-502) (Cont'd)




Figure 25 shows the data schedule from 17-SAMSS-502 that is used to order synchronousmotors.

ATTACHMENT TO 17-SAMSS-502 (20 JUN 1995)SYNCHRONOUS MOTOR DATA SHEET - INFORMATION SUPPLIED BY BUYER

Buyer's Quot. Req./P.O. No. __________ B.I./J.O. No. _______ Line Item No. ______ Quantity _______ Driven Equip. ____________ Model ________ Ser. No. ________ Driven Eq't Data Sheet No. _________________

1. Nameplate kW ____ ( ____ hp) at Unity Power Factor2. Volts _____ 3. Phases __ 4. Hz ____ 5. Synch. RPM _____6. Insul. Class: Motor ____; Exciter ____7. Temp. Rise above 50 deg C by RTD _____8. Mounting: Horizontal ___ Vertical ___9. Bearing Type: Hydrodynamic ___ Anti-friction ___10. Max. Sound Pressure Level _____ dB(A)11. Drive System:

(A) Rotation Req'd by Driven Equip. Facing Motor Oppos. Dr. End:Clockwise ___ Counterclockwise ___(B) Dir. Connected___ (C) Gear___ (D) Coupling Type ____

12. Enclosure:(A) TEFC ___ (B) CACA ___(C) TEAAC ___ Tubes: Aluminum ___ Aluminum Alloy ___ Copper ___Copper Alloy ___ Stainless Steel ___(D) Explosionproof ___ Class ___ Div. ___ Group ___ Ignition Temperature ___

13. Site Conditions: (A) Onshore ___ (B) Offshore ___ (C)Dust ___ (D)CorrosiveConditions___

14. Terminal Box Sized for(A) Main motor leads: Shielded Cable Copper EPR___ XLPE___ Size_____mm/sq____AWG/MCM No./Phase___Enter from: Above__ Below__ Side__ (R/L)Conduit Type_______; Size____; Number______(B) C.T.'s for Differential Protection Yes ___ No ___(C) Surge Protection Yes ___ No ___

Figure 25: Synchronous Motor Data Schedule (from 17-SAMSS-502)




15. Tests(A) Performance Determination: Yes ___ No ___(B) Temperature Test: Yes ___ No ___(C) Miscellaneous Test: Yes ___ No ___(D) Surge Test: Yes ___ No ___(E) Conformance Test: Immersion ___ Spray ___(F) Partial Discharge (13.2 kV only): Yes___ No___

16. Space Heater: Voltage_____; Terminal Box: Conduits:____EANPT Size:____Inch

17. Vibration Detector Terminal Box: For Conduits:_____ EANPT Size:______ Inch

18. R.T.D Terminal Box: For Conduits:_________ EANPT Size :_________ Inch

19. Exciter Terminal Box: Conduits: __________ EANPT Size: __________ Inch

20. Provide Sight Oil Gauge: Yes:_______ No:_______21. Vendor To Supply Speed-Torque And Speed-Current Curves

Yes:______ No:______

Approved by _____________________ Date _____________ ----------------------------------------------------- PLANT NO. INDEX DRAWING NO. SH. NO. REV. NO. ----------------------------------------------------- P 1 OF 2 -----------------------------------------------------

Figure 25: Synchronous Motor Data Schedule (from 17-SAMSS-502) (Cont'd)




WORK AID 2: REFERENCES FOR EVALUATING MOTOR AND GENERATORINSTALLATION AND TESTING

Unless stated otherwise, the information in this Work Aid contains combined excerpts fromaccepted industry practices and from the following resources:

• SAES-P-113, Motors and Generators

• 17-SAMSS-503, NEMA Frame Motors

• 17-SAMSS-502 Form Wound Induction and Synchronous Motors

• 17-SAMSS-510 Synchronous Generators

• GI-2.710

• NEMA MG-1

• Saudi Aramco Pre-Commissioning form P-019, NEMA Frame, Form Wound Inductionand Synchronous Motors

Work Aid 2A: Testing Requirements

The following are the minimum tests that are required for commissioning motors and generators:

• Measurement of winding resistance.

• No-load motoring readings of current, power, and nominal speed at rated voltageand frequency.

• Measurement of open-circuit voltage ratio on wound-rotor machines.

• High-potential (high-pot) test.

• Bearings/lube oil temperature measurement.

When determined by the designer, the following tests should be performed:

• Performance determination

• Temperature tests

• Miscellaneous tests

• Surge tests




Work Aid 2B: Information, Formulas, and Tables for Use in Evaluating the Results ofInsulation Resistance (Megger) Tests

The results of all commissioning megger tests that are performed must be documented on theappropriate Saudi Aramco pre-commissioning form.

For motors and generators, the acceptable values of insulation resistance only apply to insulationresistance readings that have been temperature corrected to 50oC. Before the temperaturecorrected insulation resistance readings are evaluated for acceptability or unacceptability, thesevalues must be verified through use of the following formula and table:

Rc = Kt · Rt

Where:

Rc is the insulation resistance corrected to 50oC.

Rt is the direct insulation resistance reading.

Kt is the insulation resistance temperature coefficient from the following table:

WindingTemp.

10o 20o 30o 40o 50o 60o 70o 80o 90o 100o 110o

Kt .06 .12 .25 .5 1 2 4 8 16 32 64

The following are the minimum acceptable temperature corrected values of insulation resistance:

Windings - Minimum acceptable Voltage Min. IR (M�)

13,200 15 4,000 5.5 2,400 3.5 460 1.5

Bearings - Minimum acceptable value is 200 k�, but > 1 M� is preferred.

When the dielectric absorption ratio megger test is performed, the polarization index can bedetermined through use of the following equation:




Figure 26 provides insulation conditions for 60/30 second ratio results and for 10/1 minute ratioresults.

InsulationCondition

60/30 - SecondRatio

10/1 - Minute Ratio(Polarization Index)

Dangerous ------ Less than 1

Questionable 1.0 to 1.25 1.0 to 2

Good 1.4 to 1.6 2 to 4

Excellent Above 1.6 Above 4

Figure 26: Dielectric Absorption Ratio Chart

Work Aid 2C: Information, Formulas, and Tables for Use in Evaluating the Results ofDc High-Pot Tests

For the commission dc high-pot test, the maximum test voltage must be determined as follows:

Maximum Voltage = 75%{1.7(2 · Rated Voltage + 1 kV)}

Once the maximum test voltage is determined, the initial test voltage is calculated as follows:

Initial Voltage = 33% (Maximum Voltage)

A polarization index (PI) test is performed by applying an initial voltage step of about one-third ofthe recommended maximum voltage. The initial voltage step must be maintained at a constantlevel for ten minutes. The PI is calculated by dividing the one-minute leakage current by the ten-minute leakage current. A PI value of 2.0 or less must be investigated.

After the initial ten-minute test, the dc test voltage is increased in approximately ten uniformsteps. Each step should have a one minute duration. The voltage is increased until the maximumrecommended dc value is reached.




The following are the acceptable results of a high potential test:

• The micro-amperes leakage current should decrease in value during the initial tenminutes of the test at 33% test voltage. The micro-amperes leakage current shouldshow a steady rise for the remainder of the test until the maximum test voltage isreached.

• A steady-state or rising value during the initial ten minutes of the test indicates poorinsulation and, as a result, the insulation should be rejected. A sharp or anexponential rise in leakage current during the step voltage changes and prior to theapplication of the maximum test voltage also indicates poor insulation and, as aresult, the insulation should be rejected.

The dc high-pot test should be secured if one of the following situation occurs:

• The duration of the test has expired.

• A rapid rise in leakage current occurs.

• The polarization index < 1.

The following are the characteristics of a satisfactory dc high-pot test:

• The leakage current gets smaller over time.

• The polarization index > 1.

• The leakage current increases on a straight line as voltage is increased. No "knee"is noticeable in the leakage current curve.




An example of dc high-pot test data is shown in Figure 27. Figure 27 shows typical results (bothgood and bad) of high-pot tests.

Figure 27: Typical Results of High-Pot Tests

Work Aid 2D: Miscellaneous Tests/Checks

Rotating Rectifier Diode Check

The exact values of diode resistance vary from one diode to another diode. For purposes ofmotor commissioning, the acceptable values of diode resistance are a low resistance in theforward direction and a high resistance in the reverse direction.




Air Gap Check

The minimum acceptable values for radial air gap are shown in Figure 28.

Motor Rating Minimal Radial Air GapkW H.P. (NEMA) mm (mil)

601 - 900901 -1350

1350 - 20002001 - 29002901 and up

801 - 12501250 - 17501751 - 25002501 - 40004001 and up

3.43.63.93.94.6

134142154154181

Figure 28: Radial Air Gap Values

Work Aid 2E: Acceptable Values for No Load Run Test Data

Phase Current

When the motor is started under loaded conditions, the maximum phase current values normallyrange from five to seven times the full load current of the motor. When the motor is started underno load conditions, the actual phase current values should be below this range and, in no case, canthe values exceed this range. The running values of phase current should be approximately equalto and less than the full load nameplate current rating.

Phase Voltage

The individual phase voltages (A-B, B-C, and A-C) should be equal to the nameplate voltagerating ±10%.

Percent Voltage Unbalance

Before the percent voltage unbalance can be evaluated, the percent voltage unbalance calculationmust be verified through use of the following formula:

%VU = 100(Vd / Vavg)

Where:

%VU is the percent voltage unbalance.




Vd is the maximum phase voltage deviation (VA-B, VB-C, or VA-C minus Vavg,whichever yields the highest deviation).

Vavg is the average of the individual phase voltages.

The maximum allowable percent voltage unbalance cannot exceed 1% for continuous operation.A percent voltage unbalance of 1.5% is acceptable for periods of time that are less than threeminutes.

Vibration Levels

The maximum allowable vibration levels for horizontal motors that are equipped with proximityprobes are as follows:

Motor Speed (RPM) Max. Vibration Level (Mils)

3600 2.01800 2.51200 or less 3.0

The maximum allowable vibration level for vertical and for horizontal motors that are equippedwith seismic velocity transducers is 4.6 mm/s.

Winding Temperature

The maximum winding temperature of a motor with Class B or with Class F insulation is 125oCat full load. This temperature is based on not exceeding the design temperature rise of Class Binsulation when the ambient temperature is 50oC. The actual temperature that is measured duringthe no load run test should be significantly lower.

Bearing Temperature

The maximum allowable bearing temperature of a motor that is operating at full load is 90oC or is40oC above the ambient temperature, whichever temperature is lower. The actual temperaturethat is measured during the no load run test should be significantly lower.

% Ns When Excited

The manufacturer's technical manual should be consulted for the minimum speed at whichexcitation should be applied to a given synchronous motor. If the manufacturer's technical manualis not available, the general thumb rule that is used is that excitation should not be applied until asynchronous motor reaches 97% to 98% of its rated synchronous speed.




Exciter Field Current

The manufacturer's technical manual must be consulted to obtain the acceptable value of no loadexciter field current for a given synchronous motor.

Motor Field Current

The manufacturer's technical manual must be consulted to obtain the acceptable value of no loadmotor field current for a given synchronous motor.

Power Factor

Synchronous motors are designed to operate at power factors that range from 1.0 to 0.8 leading.The manufacturer's technical manual must be consulted for the design power factor of a givensynchronous motor. The actual power factor should be equal to the design power factor whenthe excitation control circuit is in automatic. Automatic is the normal mode of excitation control.

Reactive Power (kVAR)

The maximum reactive power that a synchronous motor can supply is dependent upon the powerfactor at which the motor is operating. The maximum reactive power at a given power factor canbe calculated through use of the following equation:

kVAR = kVA · sin{cos-1(pf)}

The actual reactive power that is supplied by the motor should be consistent with the load that ison the motor and the power factor at which the motor is operating.

Work Aid 2F: Acceptable Values for Load Run Test Data

Inspection/Check of Motor Alignment

The acceptable results for this inspection/check are that the inspection/check was satisfactorilycompleted.

Phase Current

When a motor is started under loaded conditions, the maximum phase current values should rangefrom five to seven times the full load current of the motor. The running values of phase currentshould be approximately equal to each other and to the full load nameplate current rating.




Phase Voltage

The individual phase voltages (A-B, B-C, and A-C) should be equal to the nameplate voltagerating ±10%.

Percent Voltage Unbalance

Before the percent voltage unbalance can be evaluated, the percent voltage unbalance calculationmust be verified through use of the following formula:

%VU = 100(Vd / Vavg)

Where:

%VU is the percent voltage unbalance.

Vd is the maximum phase voltage deviation (VA-B, VB-C, or VA-C minus Vavg,whichever yields the highest deviation).

Vavg is the average of the individual phase voltages.

The maximum allowable percent voltage unbalance cannot exceed 1% for continuous operation.A percent voltage unbalance of 1.5% is acceptable for periods of time that are less than threeminutes.

Vibration Levels

The maximum allowable vibration levels for horizontal motors that are equipped with proximityprobes are as follows:

Motor Speed (RPM) Max. Vibration Level (Mils)

3600 2.01800 2.51200 or less 3.0

The maximum allowable vibration level for vertical and for horizontal motors that are equippedwith seismic velocity transducers is 4.6 mm/s.




Winding Temperature

The maximum winding temperature of a motor with Class F insulation is 125oC at full load. Thistemperature is based on not exceeding the design temperature rise of Class B insulation when theambient temperature is 50oC.

Bearing Temperature

The maximum allowable bearing temperature of a motor that is operating at full load is 90oC or is40oC above the ambient temperature, whichever temperature is lower.

Voltage Dip on Start (%)

The maximum voltage dip on start normally is limited to 15%. If an analysis of the othercomponents of the power system shows that these components will not be adversely affected by alarger voltage dip, a voltage dip that is in excess of 15% may be permissible.

Acceleration Time (Sec)

The manufacturer's technical manual should be consulted to obtain the design acceleration time ofa given motor. If the manufacturer's technical manual is not available, the general thumb rule isthat most motors should accelerate to rated speed within ten seconds.

% Ns When Excited

The manufacturer's technical manual should be consulted for the minimum speed at whichexcitation should be applied to a given synchronous motor. If the manufacturer's technical manualis not available, the general thumb rule that is used is that excitation should not be applied until asynchronous motor reaches 97% to 98% of its rated synchronous speed.

Exciter Field Current

The manufacturer's technical manual must be consulted to obtain the acceptable value of full loadexciter field current for a given synchronous motor.

Motor Field Current

The manufacturer's technical manual must be consulted to obtain the acceptable value of full loadmotor field current for a given synchronous motor.




Power Factor

Synchronous motors are designed to operate at power factors that range from 0 to 0.8 leading.The manufacturer's technical manual must be consulted for the design power factor of a givensynchronous motor. The actual power factor should be equal to the design power factor whenthe excitation control circuit is in automatic. Automatic is the normal mode of excitation control.

Reactive Power (kVAR)

The maximum reactive power that a synchronous motor can supply is dependent upon the powerfactor at which the motor is operating. The maximum reactive power at a given power factor canbe calculated through use of the following equation:

kVAR = kVA · sin(cos-1(pf))

The actual reactive power that is supplied by the motor should be consistent with the load that ison the motor and the power factor at which the motor is operating.

Work Aid 2G: Saudi Aramco Pre-Commissioning Form

Figure 29 shows the Saudi Aramco Pre-Commissioning Form, P-019, NEMA Frame, FormWound Induction and Synchronous Motors, which provides a field installation checklist for motorinstallations. The pre-commissioning form has a broad checklist of visual and mechanicalinspections, as well as the listed electrical and tests that are required for motor installations.Space is also provided on the form for test data.




Figure 29: Saudi Aramco Pre-Commissioning Form, P-019,NEMA Frame, Form Wound Induction and Synchronous Motors




Figure 29: Saudi Aramco Pre-Commissioning Form, P-019,NEMA Frame, Form Wound Induction and Synchronous Motors (Cont'd)




































































Work Aid 2H: Excerpts from GI 2.710

The following is an excerpt from GI 2.710, New Construction Check List Example, thatillustrates the overall checklist and sign-off for major pieces of electrical equipment.

3. Electrical Equipment

All substations, powercable, electrical equipment,including lighting andwiring, to be checked forproper application,operation, and grounds.Distribution panels,switches properly identified,and all energizationcertificate requests signed.

Construction Agency

Power Distribution Dept.

Project Inspection

Commissioning (Note 1)




Figure 30 shows an excerpt from GI 2.710, General Instruction Manual, that illustrates theinspections and tests that should be performed on major pieces of electrical equipment prior to theturnover of a facility.

Figure 30: GI 2.710 Excerpt




Figure 30: GI 2.710 Excerpt (Cont'd)




GLOSSARY

accelerating torque The torque that is developed with rated power input between zerospeed and full rated speed.

ANSI American National Standards Institute.

breakdown torque The maximum torque that is developed with rated power input.

CACA Closed Air Circuit Air-Cooled.

critical speed A speed at which the amplitude of the vibration of a rotor thatresults from shaft transverse vibration reaches a maximum value.

dielectric absorption ratio The ratio of two timed insulation resistance readings (such as a60-second reading that is divided by a 30-second reading).

duty cycle The time interval occupied by a device on intermittent duty instarting, running, stopping, and idling.

EXd Explosion-proof motor. This type of motor is enclosed in a casethat is capable of withstanding an explosion of a specified gas orvapor that may occur within it. EXd prevents the ignition of aspecified gas or vapor surrounding the enclosure by sparks, flashes,or explosion of the gas or vapor within the enclosure.

EXn Non-sparking motor.

full load torque The torque that is necessary to produce rated output at rated speedand at rated power input.

IEC International Electrotechnical Commission.

insulation resistance The amount of opposition to the flow of electric current that isofferedby an insulation.

IP Ingress Protection.

journal bearing A bearing that supports the cylindrical journal of a shaft.

locked-rotor torque The minimum torque that is developed by the motor at the instantthat rated power is supplied to the terminal of the motor.




NEMA National Electrical Manufacturer's Association.

overload Operation of equipment in excess of normal, full load rating.

polarization index The ratio of a ten-minute insulation resistance reading divided by aone-minute insulation resistance reading.

radial air gap The distance between the rotor windings and stator windings of amotor.

series motor A commutator motor in which the field circuit and armature circuitare connected in series.

sleeve bearing A bearing with a cylindrical inner surface in which the journal of arotor shaft rotates.

sound intensity The density of sound power at a point away from the source. Thisdensity of sound power is expressed in watts per square meter.Sound power that is radiated by a source may be derived byintegration of the intensity over an enclosed hypothetical surface ofmeasurement.

sound level A weighted measure of the amount of noise that is produced by amachine at a given point.

sound pressure level (SPL) The level of pressure in the sound-conducting medium that resultsfrom the sound intensity at the concerned point.

sound power (SWL) A property of the noise that is produced by a machine that isindependent of the environmental conditions or the distance fromthe machine.

shunt-wound motor A dc motor in which the field circuit and armature circuit areconnected in parallel.

TEFC Totally Enclosed Fan-Cooled.

wound-rotor An induction motor in which the secondary circuit consists ofinduction motor polyphase windings or coils whose terminals are either short-

circuited or closed through suitable circuits.

zone 1 A location in which ignitable concentrations of flammable gases orvapors can exist under normal conditions.




zone 2 A location in which volatile flammable liquids or flammable gasesare handled, processed, or used but in which the liquids, vapors, orgases will normally be confined within closed containers or closedsystems from which they can escape only in case of accidentalrupture or breakdown.

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Commissioning Motors and Generators

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