Electric Motor Terminology

8/19/2019 Electric Motor Terminology

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Electric Motor & Machines Terminology

Accelerating Time: The time required for a motor to reach full speed from standstill (zero speed)position.AC Contactor: An alternating current (ac) contactor is designed for the specific purpose of establishingor interrupting an AC power circuit.

Accelerating Torque: The torque developed from standstill (zero speed) to full speed at nameplatevoltage. Sometimes the term "et Accelerating Torque" is used to mean the e!cess motor torquecapabilit over the torque for the attached load.Adjustable Speed: The concept of varing the speed of applications.Adjustable Speed Drive: A unit comprised of a motor# drive controller and operator$s controls (eithermanual or automatic). %s also used to refer to the inverter which is a device used to convert standardsine wave power form into a simulated form for varing speed ranges on the driven equipment.Adjustable Speed Motor: A motor that can be varied in speed over a range# but a motor that isessentiall constant speed at an one set speed within that range.Aerator Motors: A specific dut motor used pump air into a sludge tpe environment. The largeair&liquid interface area provides e!cellent gas transfer and enables the sludge to be bro'en down andreccled into the environment.Air Filter: ilter made from polurethane (vertical)# zinc or stainless steel (horizontal) medium to trapairborne particles which ma clog the operations of a weather protected %% (*+%%) motor.

Air Gap: The space between the rotating and stationar member in an electric motor.Air Pressure Differential Sitc!: or use with air filters on weather protected %% (*+%%) enclosedmotors. This switch will send alarm when a concentration of particles causes a pressure drop in the airflowing through the filter and into the motor. This feature allows the air filter to be used until its ma!imumcapacit is reached.A""G#A$D% Protection: Similar to C,--,/T01 treatment on motors# A223/A- protects thegearbo! from corrosive atmospheres.Alternating Current: The commonl available electric power supplied b an AC generator anddistributed in one# two# and three phase form.Altitude: The height of the motor in reference to sea level. Standard altitude is 4455 feet# or 6555meters. Sometimes written as 4455 AS2 (feet above sea level).Ambient Temperature &Amb'(: Ambient Temperature is the temperature of the medium# such as air#water or earth# into which the heat of the equipment is dissipated.or selfventilated equipment# the ambient temperature is the average temperature of the air in the

immediate neighborhood of the equipment.or air or gas cooled equipment with forced ventilation# or secondar water cooling# the ambienttemperature is ta'en as that of the in coming air or cooling gas.or selfventilated enclosed (including oil immersed) equipment# considered as a complete unit# theambient temperature is the average temperature of the air outside of the enclosure in the immediateneighborhood of the equipment.7ost motors are designed to operate in an ambient not over 859C (6589).ote: A rating of 859C Ambient is not the same as a rating of 859C -ise; see Temperature -ise.Ampere: The rate of flow of charge in a conductor of one coulomb per second.Ampere Turn: The magnetomotive force produced b a current of one ampere in a coil of one turn.Angular Contact )earing: A specialized thrust bearing used on highthrust vertical motors. The specialangular design reduces friction and wear while supporting the rotating parts.Angular *elocit+: Angular displacement per unit time# measured in degrees&time or radians&time.Anti,Friction )earings: A bearing using balls or rollers as the supporting device between hardened

races.Anti!unt: Antihunt is the means of reducing or suppressing the oscillation of a sstem.Antiplug Protection: The effect of a control function# or a device that operates to prevent application ofcounter torque# b the motor until the motor speed has been reduced to an acceptable value.Arctic Dut+: Specific dut motors designed to withstand severel cold temperatures and environments.These motors will withstand ambient temperatures to


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Armature $eaction: The current that flows in the armature winding of a .C. motor tends to producemagnetic flu! in addition to that produced b the f ield current. This effect# which reduces the torquecapacit# is called armature reaction and can effect the commutation and the magnitude of the motor$sgenerated voltage.Armature *oltage Feedbac-: Armature voltage can be used as the speed feedbac' signal to anelectronic speed regulator. This voltage is almost directl proportional to motor speed# assuming aconstant motor field and ignoring %- drop. Armature voltage feedbac' is used where the e!pense of a

tachometer generator for speed feedbac' is not =ustified and a regulation accurac of >?@ is adequate.As+nc!ronous Motor: Also called nonsnchronous motor# is an AC motor which does not run atsnchronous speed. The ordinar induction motor is an asnchronous motor single or polphase.Automotive Dut+: Specific dut motors designed to meet the needs of the auto industr which includeall cast iron construction# special ambient and temperature rise# and special drains and breathers. (Seereference manual for actual automotive dut motor specification.)Au.iliar+ Contacts: Au!iliar contacts of a switching device are contacts in addition to the main circuitcontacts and operate with the movement of the latter.A.ial Centering Force: The magnetic force on the rotor resulting from its a!ial displacement frommagnetic center.A.is: A principal direction along which movement of the tool or wor'piece occurs. The term "a!is" alsorefers to one of the reference lines of a coordinate sstem.)andidt!: 3enerall# this is the frequenc range of a sstem input over which the sstem will respondsatisfactoril to a command.

)ase Speed: ase speed is the manufacturerBs nameplate rating where the motor will develop rated +at rated load and voltage. *ith C drives# it is commonl the point where full armature voltage is appliedwith full rated field e!citation. *ith AC sstems# it is commonl the point where D5 z is applied to theinduction motor.

)ases , Slide $ails: A two piece mounting sstem for motors which enable the motor to be mountedand leveled to the needed heights.

)ases , Sole Plates: A one piece mounting sstem for motors which enable the motor to be raised andlowered to the required height.

)earing/ &)all(: A "ball" shaped component that is used to reduce friction and wear while supportingrotating elements. or a motor# this tpe of bearing provides a relativel rigid support for the output

shaft.

/sed where higher load capacit is required or ball bearing is preference. Common means used to 'eepout dirt:

Shields E 7etal rings with close running clearance on one side (singleshielded) or both sides (doubleshielded) of bearing.Seals E Similar to shields# e!cept have rubber lips that press against inner race# more effectivele!cluding dirt# etc.)earing/ &$oller(: A special bearing sstem with clindrical rollers capable of handling belted loadapplications that are too large for standard ball bearings.

)earing/ Sleeve &Slv'(: A bearing that is made of a sleeve bushing# not a ball or roller bearing. %nfractional hp motors# sleeve bearings are used on motors with low to moderate radial and a!ial loads.

)earing/ #nit: 7otors are constructed with a long# single sleeve bearing. or fan dut onl. Allpositionmounting unless otherwise stated.)earing "ife: The e!pected endurance of motor bearings under specified load conditions. earing life isnormall stated in terms of hours or ears. Commonl referred to in motor specifications as 65 life or265 life; both are used interchangeabl.

)ipolar Transistor: ,rdinar + or ++ transistor with emitter# base and collector are called bipolarsince the operate through the collector are called bipolar since the operate through the flow of bothholes and elections. /nipolar devices# such as FT transistors# operate through the flow of minoritcarries onl# i.e. election flow.

)ra-ing: ra'ing provides a means of stopping an AC or C motor and can be accomplished in severalwas:

6. D+namic )ra-ing &DC Drives( Slows the motor b appling a resistive load across thearmature leads after disconnection from the C suppl. This must be done while the motor field


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is energized. The motor then acts as a generator until the energ of the rotating armature isdissipated. This is not a holding bra'e.

D+namic )ra-ing &AC Drives( Since AC motors do not have separate field e!citation#dnamic bra'ing is accomplished b continuing to e!cite the motor from the drive. This causesa regenerative current to the driveBs C intermediate bus circuit. The dnamic bra'e resistorsare then placed across the C bus to dissipate the power returned. The bra'e resistor is

usuall switched b a transistor or other power switch controlled b the drive.

>. $egenerative )ra-ing This is similar to dnamic bra'ing# but it is accomplishedelectronicall. The generated power is returned to the line through the power converter. %t maalso be =ust dissipated as losses in the converter (within its limitations).

4. Motor Mounted or Separatel+ Mounted )ra-e This is a positive action# mechanical# frictiondevice. ormal configuration is such that when the power is removed# the bra'e is set. Thiscan be used as a holding bra'e. (ote: A separatel mounted bra'e is one which is located onsome part of the mechanical drive train other than the motor..)

)ra-ing Torque: The torque required to bring a motor down from running speed to a standstill. Theterm is also used to describe the torque developed b a motor during dnamic bra'ing conditions.

)rea-aa+ Torque: The torque required to start a machine from standstill.

)rea-don Torque: The ma!imum torque which a motor will develop with rated voltage applied atrated frequenc# without an abrupt drop in speed.

)ridge $ectifier: A full wave rectifier that conducts current in onl one direction of the input current. ACapplied to the input results in appro!imate C at the output.

)ridge $ectifier &Diode/ SC$(: A diode bridge rectifier is a noncontrolled full wave rectifier thatproduces a constant# rectifier C voltage. An SC- bridge rectifier is a full wave rectifier with an outputthat can be controlled b switching on the gate control element.

)rus!: A brush is a conductor# usuall composed of some element of carbon# serving to maintain anelectrical connection between stationar and moving parts of a machine (commutator of a C motor).The brush is mounted in a springloaded holder and positioned tangent to the commutator segments

against which it "brushes." +airs of brushes are equall spaced around the circumference of thecommutator.

)uss Connections: An option on titan conduit bo!es. /sed to add up to three standoff insulators.

C,Face &Motor Mounting(: This tpe of motor mounting is used to close couple pumps and similarapplications where the mounting holes in the face are threaded to receive bolts from the pump.ormall# the Cace is used where a pump or similar item is to be overhung on the motor. This tpe ofmounting is a F7A standard design and available with or without feet.C,Flange: A tpe of mounting used to connect motors&gearmotors to driven equipment with dimensionsdefined b F7A. This tpe of mounting is used to close couple pumps and similar applications wherethe mounting holes in the face are threaded to receive bolts from the driven equipment.Capacitance: The value in microfarads of a capacitor or condenser.Capacitor: A device which# when connected in an alternating current circuit# causes the current to lead

the voltage in time phase. The pea' of the current wave is reached ahead of the voltage wave. This isthe result of the successive storage and discharge of electric energ.Two 'inds of capacitors are normall used in AC induction motors. A start capacitor is connected inseries with the au!iliar circuit. %t can onl sta energized for a short period of time. Therefore it is onlenergized when the motor is started and it is removed from the circuit after the motor reaches operatingspeed. The run capacitor can sta energized continuousl. Therefore# it stas in the circuit even after themotor reaches operation speed and used in +SC and the running circuit of capacitorstart capacitorrunmotors. Capacitor value and voltage rating are essential to the proper motor operation. Alwas use the correctcapacitor as specified b the motor manufacturer to insure ma!imum performance and life and safeoperation of the motor.Cascade Drive S+stem: Two or more drives connected to a master speed setting potentiometer. Themaster speed setting potentiometer sets the speed of the master drive. Fach of the slave drives has a

potentiometer of trimming the speed reference from the master speed setting potentiometer.C0MF: Abbreviation for counter electromotive force# which is the product of a motor armature rotating ina magnetic field. This generating action ta'es place whenever a motor is rotating. /nder stable motoring


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conditions the generated voltage (CF7) is equal to the voltage supplied to the motor minus smalllosses. owever# the polarit of the CF7 is opposite to that of the power being supplied to thearmature.Center Distance: The measured distance from the center of a pinion to the center of its mating gear.Centrifugal Cutout Sitc!: A centrifugall operated automatic mechanism used in con=unction withsingle phase induction motors. Centrifugal cutout switch will open or disconnect the starting windingwhen the rotor has reached a predetermined speed# and reconnect it when the motor speed falls below

it. *ithout such a device# the starting winding would be susceptible to rapid overheating and subsequentburnout.Closed "oop: Closed loop refers to a regulator circuit in which the actual value of the controlledvariable (e.g.# speed) is sensed and a signal proportional to this value (feedbac' signal) is comparedwith a signal proportional to the desired value (reference signal). The difference between these signals(error signal) causes the actual value to change in the direction that will reduce the difference in signalsto zero.Code "etter: A code letter is a letter which appears on the nameplate of alternatingcurrent motors toshow their loc'edrotor GHA per horsepower.Cogging: A term used to describe nonuniform angular velocit. %t refers to rotation occurring in =er's orincrements rather than smooth motion. *hen an armature coil enters the magnetic field produced b thefield coils# it tends to speed up and slow down when leaving it. This effect becomes apparent at lowspeeds. The fewer the number of coils# the more noticeable it can be.Commutation &DC Motors(: -eversing the current in an armature coil when the coil (ends) move from

one side of the brush to the other side of the same brush. This completes the connection between thearmature winding and the e!ternal circuit.Commutation &1nverter(: The process b which forward current is interrupted or transferred from oneswitching device to the other. %n most circuits where power is supplied from an AC source# turnoncontrol is adequate and turnoff occurs naturall when the AC ccle causes the polarit across a givendevice to reverse.Commutator: A clindrical device mounted on the armature shaft and consisting of a number of wedgeshaped copper segments arranged around the shaft (insulated from it and each other). The motorbrushes ride on the peripher of the commutator and electricall connect and switch the armature coilsto the power source.Comparator: A device that compares one signal to another# usuall the process signal compared to theset point or command signal.Computeri2ed 3umerical Control &C3C(: A numerical control sstem where a computer is used toperform some or all of the basic numerical control functions on a machine tool.

Conduit )o.: 7etal bo! on motor where motor leads terminate.Constant 4orsepoer: A multispeed wound motor where all the windings are of the samehorsepower.Constant 4orsepoer $ange: %n H applications# a range of motor operation where the motor speedis controlled b field wea'ening. %n this range# motor torque decreases as speed increases. Sincehorsepower is speed times torque (divided b a constant)# the value of horsepower developed b themotor in this range is constant.Constant Torque: A multispeed motor wound so that the horsepower varies directl as the speed.Constant Torque $ange: %n H applications# a speed range in which the motor is capable ofdelivering a constant torque# sub=ect to cooling limitations of the motor.Constant *oltage $ange &AC Drives(: The range of motor operation where the drive$s output voltageis held constant as output frequenc is varied. This speed range produces motor performance similar toa C drive$s constant horsepower range.Constant *olts Per 4ert2 &*546(: This relationship e!ists in AC drives where the output voltage is

varied directl proportional to frequenc. This tpe of operation is required to allow the motor to produceconstant rated torque as speed is varied.Control Circuit: The control circuit of a control apparatus or sstem is the circuit which carries theelectric signals directing the performance of the controller# but does not carr the main circuit power.Control Device: A control device is an individual device used to control functions.Control Transformer: A control transformer is a voltage transformer utilized to suppl voltage suitablefor the operation of control devices.Counter 0lectromotive Force: (CF7) The induced voltage in motor armature# caused b conductorsmoving through or "cutting" field magnetic f lu!. This induced voltage opposes the armature current andtends to reduce it.Conductor: An material which tends to ma'e the flow of electric current relativel eas (copper#aluminum# etc.).Contactor: A twostate (,n,ff) device for repeatedl establishing an interrupting an electric powercircuit. %nterruption is obtained b introducing a gap or a ver large impedance.

Contactor $eversing: A method of reversing motor rotation b the use of two separate contactors# oneof which produces rotation in one direction and the other produces rotation in the opposite direction. The


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contactors are electricall (and mechanicall) interloc'ed so that both cannot be energized at the sametime.Continuous Dut+: A motor that can continue to operate within the insulation temperature limits after ithas reached normal operating temperature.Continuous $ating: The ma!imum constant load that can be carried continuousl without e!ceedingestablished temperature rise limitations under prescribed conditions of load and within the limitations ofestablished standards.

Control Transformer: A control transformer is a voltage transformer utilized to suppl voltage suitablefor the operation of control devices.Converter: The process of changing AC to C and bac' to AC again. This is accomplished through theuse of a diode rectifier or thristor rectifier circuit. The term "converter" ma also refer to the processsuch that is found in an ad=ustable frequenc drive# consists of a rectifier# a C intermediate circuit# aninverter and a control unit.Copper )ar $otor: Specialized rotor construction used on high inertia applications that require high slipor torques. Centrifugal cast end rings are full brazed to each rotor bar. -otor bars are swaggedpreventing inslot movement and tight bar constructions. eav finger plates tightl hold the rotor covetogether controlling internal stress and maintaining dimension stabilit under all loads.C7$$7,D#T8 %: /.S. 7,T,-S1 brand motor product created for withstanding corrosiveenvironments.Coupling: A means for which the driven load is connected to the driver (motor). Couplings are dividedinto > halves with one placed on the motor shaft and the other on the driven equipment. The > halves

are then bolted together.Coupling Angle: The mechanical degree relationship between the rotor and the rotating electrical fieldin a motor. *hile present in both snchronous and nonsnchronous A.C. motors# it is usuall of concernin snchronous applications. At no load# the rotor poles line up e!actl with the field poles and thecoupling angle is considered to be zero. *hen a load is applied# the lines of force coupling the rotor withthe stator field are stretched# causing the rotor to fall behind the field. The mechanical angle b whichthe rotor lags behind the field is called the coupling angle. The coupling angle will continue to increasewith load until it reaches the "pullout" point. The ma!imum angle which is possible prior to pullout isdependent on motor tpe and rotor design.Critical Speed: All rotating masses have a socalled critical speed (-+7) where abnormal vibrationsoccur. %nduction motors (rotors)# generall run well above this speed# but occasionall in redesigning the critical speed ma occur at or near the operating speed and intolerable situation.Crus!er Dut+: Specificdut motor design including special rotor# larger shaft (if needed)# increasedloc'ed rotor and brea'down torques# end turn bracing and loc' washers# and minimized stress riser.

Current "imit: An electronic method of limiting the ma!imum current available to the motor. This isad=ustable so that the motorBs ma!imum current can be controlled. %t can also be preset as a protectivedevice to protect both the motor and controller from e!tended overloads.Current "imit Acceleration: A sstem of control in which acceleration is so governed that the motorcurrent does not e!ceed an ad=ustable ma!imum value.Current "imiting Fuse: A fuse that# when it is melted b a current within its specified current limitingrange# abruptl introduces a high impedance to reduce the current magnitude and duration.Current $ela+: A current rela functions at a predetermined value of current. %t ma be an overcurrentrela# an undercurrent rela or a combination of both.Current Transformers: ,ption available on titan motors to maintain the same magnitude of currentflowing in and out of each phase of the motor winding. A brea'down in the insulation sstem alters thisbalance resulting in measurable "difference" when the current flowing in and out of each circuit iscompared for smmetr. An dissimilarit within an individual circuit is 'nows as "differential current"which can be detected with current transformers that provide differential protection.

D,Flange &Mounting(: A tpe of motor mounting used when the motor is to be built as part of themachine. The mounting holds of the flange are not threaded. The bolts protrude through the flange fromthe motor side. ormall# flange motors are supplied without feet since the motor is mounted directlto the driven machine.Damping: amping is the reduction in amplitude of an oscillation in the sstem.Dead )and: The range of values through which a sstem input can be changed without causing acorresponding change in sstem output.Deceleration Time: The time required to stop a motor whether free running or with some bra'ingmeans.Definite Purpose Motor: A definite purpose motor is an motor design# listed and offered in standardratings with standard operating characteristics and mechanical construction# for use under serviceconditions other than usual or for use on particular tpe of application (F7A). An e!ample would avertical holloshaft motor.Deviation: ifference between an instantaneous value of a controlled variable and the desired value of

the controlled variable corresponding to the set point. Also called an error.


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di5dt: The rate of change in current versus a rate of change in time. 2ine reactors and isolationtransformers can be used to provide the impedance necessar to reduce the harmful effects thatunlimited current sources can have on phase controlled rectifiers (SC-Bs).Dimension Draing: A dimension drawing or outline drawing (base plan or floor plan) is one whichshows the phsical space and mounting requirements of a piece of equipment. %t ma also indicateventilation requirements and space provided for connections or the location to which connections are tobe made.

Diode: A device that passes current in one direction# but bloc's current in the reversed direction.DC Contactor: A contactor specificall designed to establish or interrupt a direct current power circuit.DC Motor , Compound 9ound: Tpe of C motor having both shunt and series field connections. Thismotor has good speed regulation and starting torque.DC Motor , Permanent Magnet: Tpe of C motor where the field poles and the armature poles areelectromagnets. The onl current used b the motor is that of the armature. as high starting torque#good speed regulation and a definite ma!imum speed.DC Motor , Series 9ound: Tpe of C motor which has its field winding connected in series with thearmature. This motor has ver high starting torque# but has a tendenc to Irunawa$ when lightl loadedor unloaded# and has poor speed regulation.DC Motor , S!unt 9ound: Tpe of C motor which has its armature winding and field winding done inparallel circuits. This motor has ver good speed regulation.Distributed Pole: A motor has distributed poles when its stator or field windings are distributed inad=acent slots located within the arc of the pole.

Drain5)reat!er: A hole located in the lowest spot of the motor used to drain oil&grease when relubricating the motor.Drift: rift is the deviation from the initial set speed with no load change over a specific time period.ormall# the drive must be operated for a specified warmup time at a specified ambient temperaturebefore drift specifications appl. rift is normall caused b random changes in operating characteristicsof various controller components.Drip Cover: A metal piece shaped li'e a pizza pan attached to the top of a motor mounted verticallshaft down to protect liquid from entering into the motor.Drive Controller &Also variable speed drive(: An electronic device that can control the speed# torque#horsepower and direction of an AC or C motor.Dual *oltage: A connection method with enough leads in the terminal bo! to permit simple reconnectionto either of two voltages.Dut+ C+cle: The relationship between the operating and rest time. A motor which can continue tooperate within the temperature limits of its insulation sstem# after it has reached normal operating

(equilibrium) temperature is considered to have a continuous dut (C,T.) rating. ,ne which neverreaches equilibrium temperature# but is permitted to cool down between operations is operating underintermittent dut (%T.) conditions.dv5dt: The rate of change in voltage versus a rate of change in time. *hen a motor is operated underH power a high value of dv&dt will indicate voltage spi'es and&or line disturbances.Dell: The time spent in one state before moving to the ne!t. %n motion control applications# fore!ample# a dwell time ma be programmed to allow for a tool change or part clamping operation.D+namic )ra-ing: This is caused b current being applied to the windings after the power is shut off.This is accomplished b either e!citation (.C. motors) or b separate e!citation# A.C. motors. %t isseldoml used to hold a load# but it can be used as a retarding force to prevent overrunning.D+namic #nbalance: A noise producing condition caused b nonsmmetrical weight distribution of arotating member. The lac' of a uniform wire spacing in a wound armature or casting voids in a rotor orfan assembl can cause relativel high degrees of unbalance.0dd+ Current: 2ocalized currents induced in an iron core b alternating magnetic f lu!. These currents

translate into losses (heat) and their minimization is an important factor in lamination design.0dd+ Current )ra-e: A unit consisting of a rotating member 'eed to a straight through# doublee!tension shaft and a f ield coil assembl. The bra'e rotor rotates at the speed of the prime mover untilthe field coil is energized. -otation of the rotor is slowed b controlling the current in the field coil.0dd+ Current Clutc!: A device that permits connection between a motor and a load b electrical(magnetic) means no phsical contact is involved. This method is also used for speed control (bclutch "slippage").0dd+ Current Drive: A unit consisting of a driving member which is the drum assembl# the drivenmember which is the rotor assembl# and a magnetic member which is the field coil assembl. Thedriven member is driven b a constant speed AC motor. Control of the edd current drive is obtained bcontrolling the current in the field coil.0fficienc+: The efficienc of a motor is the ratio of mechanical output to electrical input. %t representsthe effectiveness with which the motor converts electrical energ into mechanical energ at the outputshaft. The higher the efficienc# the better the conversion process and the lower the operating costs.

0lectrical Coupling: *hen two coils are so situated that some of the flu! set up b either coil lin'ssome of the turns of the other# the are said to be electricall coupled.


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0lectrical Degree: A unit of measurement of time as applied to alternating current. ,ne complete ccleJ 4D5 electrical degrees. ,ne ccle in a rotating electric machine is accomplished when the rotating fieldmoves from one pole to the ne!t pole of the same polarit. There are 4D5 electrical degrees in this timeperiod. Therefore# in a two pole machine there are 4D5 degrees in one revolution# and the electrical andmechanical degrees are equal. %n a machine with more than two poles# the number of electrical degreesper revolution is obtained b multipling the number of pairs of poles b 4D5.0lectrical Time Constant: The ratio of electrical inductance to armature resistance.

0lectromotive Force: (F7) A snonm for voltage# usuall restricted to generated voltage. %n Cad=ustable speed drives# voltage applied to the motor armature from a power suppl is the F7 and thevoltage generated b the motor is the counterelectromotive force# or C7F.0lectronic DC Motor Controller: An electronic direct current motor controller is a phasecontrolledrectifing sstem using semiconductors for power conversion to suppl the armature circuit or thearmature and shunt field circuits of a direct current motor to provide ad=ustable speed# ad=ustable andcompensated speed# or ad=ustable and regulated speed characteristics.0nable: To allow an action or acceptance of data b appling an appropriate signal to the appropriateinput.0ncapsulated 9inding: A motor which has its winding structure completel coated with an insulatingresin (such as epo!). This construction tpe is designed for e!posure to more severe atmosphericconditions than the normal varnished winding.0nclosure: Fnclosure refers to the housing in which the controller is mounted. Fnclosures are availablein designs for various environmental conditions.

efines the motor construction according to environmental protection and method of cooling. Tpesinclude:

7pen: A motor that has openings# which permit passage of e!ternal cooling air over andaround the windings. /suall used indoors# in fairl clean locations.Dripproof57pen Dripproof &DP57DP(: orizontal motor term indicating a machine in whichthe ventilating openings are so constructed that successful operation is not interfered withwhen drops of liquid# or solid particles# stri'e# or enter# the enclosure at an angle from 5 to 6?9downward from the vertical.Dripproof Guard &DPG(: An open dripproof machine in which all openings giving direct accessto live metal or rotating parts (e!cept smooth rotating surfaces) are limited in size b thestructural parts# or b the screens# baffles# grilles# e!panded metal# or other means to preventaccidental contact with hazardous parts. ,penings giving direct access to such live or rotatingparts shall not permit the passage of a clindrical rod 5.


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watercooled heat e!changer for cooling the internal and a fan(s)# integral with the rotor shaftseparate# for circulating the internal air. (esign not offered in /.S. 7,T,-S1 brand productline.)9as!don Dut+: A machine designed specificall for the food processing industr and otherapplications that are routinel e!posed to washdown# chemicals# humidit# and other severeenvironments.9eat!er Protected 1 &9P1(: A vertical or large horizontal machine which has ventilating

passages constructed to minimize the entrance of rain# snow# airborne particles and preventpassage of a 5.


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Feedbac-: As it generall relates to motors (gearmotors) and controls# feedbac' refers to the voltageinformation received b a feedbac' circuit. epending on a predetermined potentiometer setting# amotor control can correct the voltage to deliver appropriate speed and&or torque.

Ferromagnetic: A material with high magnetic permeabilit (imposes little resistance to orientation inthe presence of a magnetic field). Such materials as iron# steel# and nic'el are ferromagneticsubstances.

Field: A term commonl used to describe the stationar (stator) member of a .C. motor. The fieldprovides the magnetic field with which the mechanicall rotating (armature) member interacts.

Field Control: 7ethod of controlling C motor speed b varing the field current in the shunt fieldwindings.

Field 0conom+: A circuit design feature of a C motor shunt field suppl that reduces the supplvoltage output after a predetermined period of time. ,n ma field supplies# this means ?5@ reduction inoutput voltage > to 4 minutes after machine shutdown (idle). A field econom circuit serves to reducestandb power consumption and prolong the insulation life of the motor field windings.

Field Forcing: Temporaril overe!citing a motor shunt field to overcome the 2&- time constant#increase the rate of flu! change and rapidl reverse the direction of shunt motor field current.

Field $ange: The range of motor speed from base speed to the ma!imum rated speed.

Field $eversing: ,ne method for producing regeneration. %t is accomplished b changing the directionof current through the motor field# which reverses the polarit of the motor CF7 to account forgenerator action.

Field 9ea-ening: The introduction of resistance in series with the shunt wound field of a motor toreduce the voltage and current which wea'ens the strength of the magnetic filed and thereb increasethe motor speed.

Filter: A device that passes a signal or a range of signals and eliminates all others.

Flu.: The magnetic field which is established around an energized conductor or permanent magnet.The field is represented b flu! lines creating a flu! pattern between opposite poles. The densit of theflu! lines is a measure of the strength of the magnetic field.

F7D0 &From 7pposite Drive 0nd(: A wa to view the motor. rom opposite drive end refers to loo'ingat the motor from opposite the shaft end.

Folloer Drive: A drive in which the referenced input and operation are direct functions of anotherdrive# called the master drive.

Four,@uadrant 7peration: The four combinations of forward and reverse rotation and forward andreverse torque of which a regenerative drive is capable:

6. orward rotation&forward torque (motoring)

>. orward rotation&reverse torque (regeneration)

4. -everse rotation&reverse torque (motoring)

8. -everse rotation&forward torque (regeneration)

Force: The tendenc to change the motion or position of an ob=ect with a push or pull. orce ismeasured in ounces or pounds.

Form Factor: A figure of merit which indicates how much rectified current departs from pure (nonpulsating) .C. A large departure from unit form factor (pure .C.) increases the heating effect of themotor and reduces brush life. 7athematicall form factor is the ratio of the rootmeansquare (rms)value of the current to the average (av) current of %rms&%av.

Form 9ound Coils: Coils wound in form and shaped read to insert into the slot of a motor.

Fractional 4orsepoer Motor: A motor with a continuous rating of less than one horsepower.


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Frame: The main motor housing. Can be constructed of aluminum# steel# or cast iron.

Frame Si2e: /suall refers to the F7A sstem of standardized motor mounting dimensions# whichfacilitates interchangeabilit. The phsical size of a motor# usuall consisting of F7A defined "" and"" dimensions at a minimum. The "" dimension is the distance in quarter inches from the center of themotor shaft to the bottom of the mounting feet. The "" dimension relates to the distance between thecenters of the mounting feet holes.

Frequenc+: The rate at which alternating current reverses its direction of flow. 7easured in hertz (z); 6z J 6 ccle per second.

Full,"oad Amps &F"A(: 2ine current (amperage) drawn b a motor when operating at rated + andvoltage. Shown on motor nameplate. %mportant for proper wire size selection# motor starter heaterselection# and over current protection.Full "oad Current: The current drawn from the line when the motor is operating at full load torque andfull load speed at rated frequenc and voltage.

Full "oad Speed: The speed that the output shaft of the drive motor attains with rated load connectedand with the driveBs controller ad=usted to deliver rated output at rated speed. This will alwas be lessthan the snchronous speed and will var depending on the rating and characteristics of the particularmotor. or e!ample# four pole D5 z fractional horsepower motors have a snchronous speed of 6L55-+7# a nominal full load speed (as shown on the nameplate) of 6? -+7# and an actual full load

speed ranging from 6


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GT7: 3ate turnoff or gate turnon power semiconductor device.Guide )earing: A bearing on vertical motors which acts as the guide in shaft alignment.4alf 9ave $ectification: %n the rectifing process# half wave rectification passes onl onehalf of eachincoming sinusoid# and does not pass the opposite half ccle. The output contains a single half sinepulse for each input ccle. A single rectifier provides half wave rectification.4a2ardous "ocation Motor : A totall enclosed motor designed to withstand an internal e!plosion ofspecified gases or vapors and not allow the internal flame or e!plosion to escape. (+reviousl referred

to as F!plosionproof)4a2ardous "ocation Divisions: The first classification of hazardous location motors as developed bthe ational Flectrical Code (FC). ivisions divide the motor environment into areas where the danger of e!plosion is alwas present (division 6) and areas where onl under certain conditions is the dangerof e!plosion present (division >).4a2ardous "ocation Groups: The third classification of hazardous location motors as developed bthe ational Flectrical Code (FC). 3roups divide the motor classes even further b grouping togethersimilar liquids# vapors# dusts# and flings.4a2ardous "ocation "abels: %n electric motors the hazardous location label describes whether themotor is good for liquids onl# or for liquids# vapors# dusts# and flings.4ead: A measurement of pressure# usuall in feet of water. A 45 foot head is the pressure equivalent tothe pressure found at the base of the column of water 45 feet high.4eater Coil &T!ermal 7verload $ela+(: A heater coil is a part of a thermal overload rela that isintended to produce heat when conducting current. eater coils are sometimes referred to as heaters#

thermal units# current elements or heater elements.4eat "oss: 2osses due to resistance ta'e the form of heat which has to be dissipated into the air orsurrounding cooling medium. eat loss is also referred to as %>- loss because the current squared#multiplied b the resistance will ield the heat loss value (in watts).4eat "oss at Full "oad: The total heat loss at full load of a motor usuall given in Gilowatts. This valueis needed to determine total power requirements when a number of motors are supplied b a powersource# or more often when the motor or motors are in an enclosed area# to fine the cooling needed.4eat "oss From Starting: A necessar figure to answer two questions: (6) %f the motor is started oftenwill the accumulated heat damage the winding# and (>) oes additional cooling have to be added toovercome this accumulated heat from starting.4ert2 &42(: requenc# in ccles per second# of AC power; usuall D5 z in the /SA and ?5 zoverseas.4ig! Potential Test: A test which consists of the application of a voltage higher than rated between thewinding and the frame or between two or more windings for the purpose of determining the adequac

against brea'down of insulating materials and spacings under normal conditions. %t is not a test of theconductor insulation in an one winding.4orsepoer: 44#555 foot pounds of wor' per minute or ??5 foot pounds per second.4ot Spot Alloance: An insulation sstem is onl as good as its wea'est lin'. Thus it is necessar tolocate the hottest part of the machine as this limiting temperature determines the motor life. Thedifference in degrees of temperature between the readil accessible points and the true "hotspot" iscalled the hot spot allowance.4unting: /ndesirable fluctuations in motor speed that can occur after a step change in speed reference(either acceleration or deceleration) or load.4+steresis "oss: The resistance offered b materials to becoming magnetized results in energ beinge!pended and corresponding loss. steresis loss in a magnetic circuit is the energ e!pended tomagnetize and demagnetize the core.1nde. of Protection Code: A Furopean definition describing motor enclosures. Common ones are %+?? totall enclosed fan cooled# and %+>4 weather protected %. See charge in enclosure for the complete

listing.

1nductance: The characteristic of coil or wire to cause the current to lag the voltage in time phase. Thecurrent reaches its pea' after the voltage does.

1nduction Motor: An alternating current motor in which the primar winding on one member (usuall thestator) is connected to the power source. A secondar winding on the other member (usuall the rotor)carries the induced current. There is no phsical electrical connection to the secondar winding; itscurrent is induced.

1nertia: A measure of a bod$s resistance to changes in velocit# whether the bod is at rest or movingat a constant speed. The velocit can be either lineal or rotational. The moment of inertia (*G>) is theproduct of the weight (*) of an ob=ect and the square of the radius of gration (G>). The radius ofgration is a measure of how the mass of the ob=ect is distributed about the a!is of rotation. *G> isusuall e!pressed in units of lb. ft.>.


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1nertial "oad: A load (flwheel# fan# etc.) which tends to cause the motor shaft to continue to rotate after the power has been removed (stored 'inetic energ). %f this continued rotation cannot be tolerated#some mechanical or electrical bra'ing means must normall be applied.

1nline T!rust Motor: A specialized vertical solid shaft motor which can handle thrust values up to >555pounds (depending on the horsepower and speed) and the thrust can be either up or down thrust.

1nstabilit+: The state or propert of a sstem where there is an output but no corresponding input.

1nsulation &1ns'(: %n motors# usuall classified b ma!imum allowable operating temperatures asdefined b /.2.:Class A 65?9C (>>69)Class 6459C (>DD9)Class 6??9C (4669)Class 6L59C (4?D9)1nsulator: A material which tends to resist the f low of electric current (paper# glass# etc.).

1ntegral 4orsepoer Motor: %n terms of +# a motor built in a frame having a continuous rating of onehorsepower or more. An integral horsepower motor is in the 6 to ?55 horsepower range.

1nterconnection Diagram: An interconnection diagram is a diagram which shows onl the e!ternal

connections between controllers and associated machiner and equipment.

1ntermittent Dut+: A motor that never reaches equilibrium temperature# but is permitted to cool downbetween operations. or e!ample# a crane# hoist# or machine tool bar is often rated for 6? or 45 dut.

1nterrupting Capacit+: The interrupting capacit is the ma!imum value of current that a contactassembl is required to successfull interrupt at a specified voltage for a limited number of operationsunder specified conditions.

1nverter: A term commonl used for an AC ad=ustable frequenc drive. An inverter is also a term used todescribe a particular section of an AC drive. This section uses the C voltage from a previous circuitstage (intermediate C circuit) to produce an AC current or voltage having the desired frequenc.

1$ Compensation: A wa to compensate for the voltage drop across resistance of the AC or C motorcircuit and the resultant reduction in speed. This compensation also provides a wa to improve thespeed regulation characteristics of the motor# especiall at low speeds. rives that use a tachometergenerator for speed feedbac' do not require an %- compensation circuit because the tachometer willinherentl compensate for the loss in speed.

1solation Transformer: A transformer that electricall separates the drive from the AC power line. Anisolation transformer provides the following functions:

6. %n C motor applications# it guards against inadvertent grounding of power plant lines throughgrounds in the C motor armature circuit.

>. Fnhances protection of semiconductors from line voltage transients.

4. -educes disturbances from other solid state control equipment such as drives without isolation

transformers# time cloc' sstems and electronic counters.ogging: A means of accomplishing momentar motor movement b repetitive closure of a circuit usinga pushbutton or contact elements.Binetic 0nerg+: The energ of motion possessed b a bod."eads: The wires e!iting out of the motor terminal bo! used to connect the motor and&or accessories tothe power suppl."ine *oltage: Holtage supplied b the power compan or voltage supplied as input to the device."inear Acceleration5Deceleration &"AD(: A Circuit that controls the rate at which the motor is allowedto accelerate to a set speed or decelerate to zero speed. ,n most drives# this circuit is ad=ustable andcan be set to accommodate a particular application."inearit+: The measure of the ma!imum deviation between the actual speed and the set speed#e!pressed as a percentage of set speed."oc-ed,$otor Current: The steadstate current ta'en from the line with the rotor loc'ed and with ratedvoltage (and rated frequenc in the case of alternatingcurrent motors) applied to the motor.

"oc-ed,$otor Torque: (Static Torque) The loc'edrotor torque of a motor is the minimum torque whichit will develop at rest for all angular positions of the rotor# with rated voltage applied at rated frequenc.


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"ong S!aft Motor: F7A standard 736 defines shaft length as the dimension A# or the distancefrom the face# flange or base of the machine to the end of the shaft. %n a standard tpe "T" frame theF7A standard shaft e!tension (long shaft) is supplied. %t is normall used where overhung loads frompulles# shieves and sproc'ets are encountered.Magnetic Polarit+: %t is a fundamental principle of winding that ad=acent poles must be wound to giveopposite magnetic polarit. This does not mean that the coils actuall have to be wound in this directionbefore being placed into the stator. %t does mean that the winding must be connected so that# if the

current proceeds through one pole in a cloc'wise direction# it must proceed through the ne!t pole in acountercloc'wise direction. This principle is used to determine the correctness of connection diagrams.Marine Dut+ Motor: A specialized motor designed for use onboard ships. 7otors are designed per%FFF 8? motor specification.Master Drive: A drive that sets the reference for one or more follower drives.Mec!anical Degree: The popular phsical understanding of degrees (4D5 degrees J 6 revolution).Mego!m Meter: A device used to measure an insulation sstemBs resistance. This is usuall measuredin megohms and tested b passing a high voltage at low current through the motor windings andmeasuring the resistance of the various insulation sstems.Modular Construction: The ma=or circuit elements are mounted in replaceable modules which canreadil be removed and replaced. Fquipment can be serviced without dela.Module: A unit of circuit elements usuall pac'aged so it can be readil replaced.Motor Constant: The ratio of motor torque to motors input current (motor torque per amp).Mounting &Mtg'(: E asic tpes:

6. olted E 7otor is attached to frame with removable bolts.

>. -igid E 7otor solidl fastened to equipment through metal base that is welded# bolted# or castinto the metal shell or clamped to the end shield hubs.

4. Cradle&-esilient (-es.) E 7otor shell isolated from base b vibration absorbing material# suchas rubber rings on the end shields# to reduce transmission of vibration to the driven equipment.

8. ace or lange E Shaft end has a flat mounting surface# machined to standard dimensions#with holes to allow eas# secure mounting to driven equipment. Commonl used on pumps# oilburners and gear reducers.

?. Stud E 7otor has bolts e!tending from front or rear# b which it is mounted. ,ften used onsmall# directdrive fans and blowers.

D. 0o'e E Tabs or ears are welded to motor shell# to allow bolting motor to a fan column orbrac'et.

Multi Motor 7peration: A sstem in which one controller operates two or more motor simultaneousl#maintaining a constant ratio between the speeds of the motors.Multi Speed Motor: An induction motor that can obtain tow# three# or four discrete (fi!ed) speeds b theselection of various stator winding configurations.Mus! 9ound Coils: Also called random wound coils *here the turns are wound without definiteplacement# or# at random. 7ost small motors up to >? + are mush wound although motors up to 6?5+ have been successfull wound without formed coils. The limit is not the horsepower# but did themanufacturer allow enough slot space for the wasteful# random wound coil.

3ational 0lectrical Code &30C(: The recommendation of the ational ire +rotection Association andis revised ever 4 ears. The FC determines the divisions# classes# groups# and temperature codes ofhazardous location motors.3ational 0lectrical Manufacturers Association &30MA(: A nonprofit organization organized andsupported b manufacturers of electrical equipment and supplies. Some of the standards F7Aspecifies are horsepower ratings# speeds# frame sizes and dimensions# and torques and enclosures.30C: The ational Flectrical Code is the recommendation of the ational ire +rotection Associationand is revised ever three ears. Cit or state regulations ma differ from these code regulations andta'e precedence over FC rules.3egative Feedbac-: A condition where feedbac' is subtractive to the input reference signal. egativefeedbac' forms the basis for automatic control sstems.3egative Torque: A torque developed in opposition to the normal torque of the motor. This ma occur atstarting (common to > pole motors) or at some speed below nameplate -+7. This causes "cusps" or"saddles" in the graphed torque curves.

30MA Design A Motors: Classification of motors b F7A used on machines such as fans# blowers#pumps and compressors# requiring relativel low starting torque followed b increasing torque with


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increasing speed up to the fullload speed and torque. esign A motors are differentiated from design motors b a higher loc'edrotor current.30MA Design ) Motors: Classification of motors b F7A used on machines such as fans# blowers#pumps and compressors# requiring relativel low starting torque followed b increasing torque withincreasing speed up to the fullload speed and torque. This is the most popular motor design.30MA Design C Motors: Classification of motors b F7A used on machines such as reciprocating air compressors and conveors# requiring relativel high starting torque that is normall greater than the

torque required at fullload speed.30MA Design D Motors: Classification of motors b F7A used on machines that impose pulsatingloads or require frequent starting of the motor# such as punch press# oil well pumping# and hoistapplications. esign motors are not offered b as part of the /.S. 7,T,-S1 brand product line.3FPA: ational ire +rotection Association. The group that prepares and published the ational FlectricCode# azardous Chemicals# and numerous other such publications.3o "oad: The state of a machine rotating at normal speed under rated conditions# but when no output isrequired from it.3on,$everse $atc!et: A feature on vertical motors for use in deep well applications where waterlubricated pump bearings are installed. These ratchets stop the shaft from spinning once the power isdiscontinued and the pump water column is receding. /.S. 7,T,-S1 brand products use a balltpenonreverse ratchet which has e!tended life over pin tpes as used b other vertical motormanufacturers.7ff Dela+: ,ff dela signifies that the timing period of a time dela rela is initiated upon deenergizing

of its coil.

7ffset: The stead state deviation of a controlled variable from a fi!ed setpoint.

7il Mist "ubrication: A centralized lubricating sstem in which the energ of compressed gas# usuallair ta'en from the plant suppl# is used to atomize oil. ,il is then conveed b the air in a low pressuredistribution sstem to multiple point of lubricant application.

7n Dela+: ,n dela signifies that the timing period of a time dela rela is initiated upon energization ofits coil.

7pen Circuit: An open circuit in a motor is a defect which causes an interruption in the path throughwhich the electric current normall flows.

7pen "oop: A control sstem that lac's feedbac'.

7perating 7verload: ,perating overload is the overcurrent to which an electric apparatus is sub=ectedin the course of the normal operating conditions that it ma encounter. or e!ample# those currents ine!cess of running current which occur for a short time as a motor is started or =ogged are considerednormal operating overloads for a control apparatus.

7p Amp: An operational amplifier is usuall a high gain C amplifier that is designed to be used withe!ternal circuit elements to perform a specified computing operation.

7pen Mac!ine &Motors(: A machine having ventilating openings which permit passage of e!ternalcooling air over and around the windings of the machine.

6. Drip,proof Mac!ine , is an open tpe machine in which the ventilating openings are so

constructed that successful operations is not interfered with when drops of liquid or solidparticles stri'e or enter the enclosure at an angle from 5 to 6? degrees downward fromvertical.

>. Splas!,proof , is an open machine in which the ventilating openings are so constructed thatsuccessful operation is not interfered with when drops of liquid or solid particles stri'e or enterthe enclosure at an angle not greater than 655 degrees downward from the vertical.

4. Semiguarded is an open machine in which part of the ventilating openings in the machine#normall in the top half# are guarded as in the case of a "guarded machine#" while the otherparts are left open.

8. Guarded Mac!ine &30MA Standard( is an open machine in which all openings giving directaccess to live metal or rotating parts (e!cept smooth rotating surfaces) are limited in size bthe structural parts or b the screens# baffles# grilles# e!panded metal or other means to


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prevent accidental contact with hazardous parts. ,penings giving direct access to such live orrotating parts shall not permit the passage of a clindrical rod 5.


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P!ase: +hase is a term# which indicates the space relationships of windings# and changing values ofthe recurring ccles of A.C. voltages and currents. ue to the positioning (or the phase relationship) ofthe windings# the various voltages and currents will not be similar in all aspects at an given instant.Fach winding will lead or lag another# in position. Fach voltage will lead or lag another voltage# in time.Fach current will lead or lag another current# in time.P!ase/ Single: Available in these tpes:

6. Shaded +ole E 2ow starting torque. /suall used in directdrive fans and blowers.

>. +ermanent Split Capacitor (+SC) E +erformance and applications similar to shaded pole butmore efficient# with lower line current and higher horsepower capabilities.

4. Split+hase Start# %nduction -un (or simpl Split+hase) E 7oderate starting torque# highbrea'down torque. /sed on easstarting equipment such as beltdriven fans and blowers#grinders# centrifugal pumps# gear motors# etc.

8. Split+hase Start# Capacitor -un E Same performance as induction run# e!cept higherefficienc.

?. Capacitor Start# %nduction -un (or Capacitor Start) E igh starting and brea'down torque#medium starting current. /sed on hardstarting applications: compressors# positivedisplacement pumps# farm equipment# etc.

D. Capacitor Start# Capacitor -un E Similar to capacitor start# induction run# e!cept have higherefficienc. 3enerall used in higher + singlephase ratings.

P!ase/ T!ree: ,perate on threephase power onl. igh starting and brea'down torque# high efficienc#medium starting current# simple# rugged design# long life. or industrial uses.P!ase Control: The process of varing the point within the ccle at which forward conduction ispermitted to begin.Pic-up *oltage or Current: The pic'up voltage or current of a magneticall operated device is thevoltage or current at which the device operates.Pigg+bac- Mounting: A mounting configuration where the motor is mounted to the top of the gearbo!

and then the motor shaft is connected to the gearbo! input shaft b belts.Plain )earing: A term used for a nonball or roller bearing# i.e.# a sleeve bearing.Plate )earing: A specialized vertical motor bearing which has practicall unlimited life factor if the thrustcapacit is properl selected# lubricated# cooled and not overloaded. Hibration# cavitation and heat canseverel affect the life of this tpe bearing. Construction of this bearing calls for a solid plate runner andsegmental pivoted shoes with the runner riding on a film of oil between it and the bearing shoes.,peration at higher loads than designed for# or higher temperatures# ma brea' down the film of oil anddestro the bearing.Plugging: +lugging refers to a tpe of motor bra'ing provided b reversing either voltage polarit orphase sequence so that the motor develops a countertorque which e!erts a retarding force to bra'e themotor.Plug $eversal: -econnecting a motor$s windings to reverse its direction of rotation while running. Although it is an effective dnamic bra'ing means in man applications# plugging is more severe thanother methods and should be used with caution.

Polarities: Terms# (+ositive# egative: orth and South) which indicate the direction of current and flu!flow in electrical and magnetic circuits at an given instant.Polari2ation 1nde.: A term used to indicate the insulation value to ground of a winding. Actuall theinde! determines the moisture content of a winding.Pole: A definite group of coils connected in series that will show a uniform polarit with C currentapplied. This can also be onl one coil. This also applies to AC current rotating equipment.Position Transducer: An electronic device (e.g.# encoder or resolver) that measures actual positionand converts this measurement into a feedbac' signal convenient for transmission. This signal ma thenbe used as an input to programmable controller which controls the parameters of the positioningsstem.Positive Feedbac-: +ositive eedbac' is a condition where the feedbac' is additive to the input signal.Potentiometer: A three terminal rheostat# or a resistor with one or more ad=ustable sliding contacts# thatfunction as an ad=ustable voltage divider.Poer: *or' done per unit of time. 7easured in horsepower or watts (6 + J 44#555 ft. lb.&min. J


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Poer Factor: A measurement of the time phase difference between the voltage and current in an A.C.circuit. %t is represented b the cosine of the angle of this phase difference. or an angle of 5 degrees#the power factor is 655@ and the volt&amperes of the circuit are equal to the watts.Poer Factor Correction Capacitor: A device used to raise the power factor on motors to avoidpenalties from utilities for low power factors. This is because induction electrical equipment ta'es morepower from the electrical suppl sstem than is necessar to produce the wor' required. A properlsized capacitor will offset most of the lagging current of a motor and raise its power factor to about K?@.

Poer Suppl+: The voltage of the suppl line# which can be single phase or three phase.Preset Speed: +reset speed refers to one or more fi!ed speeds at which the drive will operate.Printed Circuit )oard: A board for mounting of separatel manufactured components which has theconnections made b printed circuitr.Pron+ )ra-e: A simple mechanical device# normall a wooden piece with an ad=ustable leather strapused to test torque output. The pron bra'eloads the motor and a spring scale attached to it gives arelativel accurate measurement of torque.Pull,7ut Torque: The pullout torque of a snchronous motor is the ma!imum sustained torque whichthe motor will develop at snchronous speed with rated voltage applied at rated frequenc and withnormal e!citation.Pull #p Torque: The minimum torque developed during the period of acceleration from loc'edrotor tothe speed at which brea'down torque occurs. %t is usuall e!pressed as a percentage of fullload torque.Pulse: A pulse is a signal of relativel short duration.Pulse 9idt! Modulating 1nverter &P9M(: A tpe of AC ad=ustable frequenc drive that accomplishes

frequenc and voltage control at the output section (inverter) of the drive. The drive$s C bus voltage isalwas a constant amplitude and b "chopping" (pulse width modulating)# the average voltage iscontrolled.Pus!,)utton: A pushbutton is a switch of relativel short durationP9M: A tpe of AC ad=ustable frequenc drive that accomplishes frequenc and voltage control at theoutput section (inverter) of the drive. The driveBs C bus voltage is alwas a constant amplitude and b"chopping" (pulse width modulating)# the average voltage is controlled.@S >: Automotive ut Mualit Specification$adial Magnetic Pull: The magnetic force on the rotor resulting from its radial (air gap) displacementfrom magnetic center.

$andom 9ound Coils: Also called mush wound coils where the turns are wound without definiteplacement# or# at random.

$eactance: The opposition to the flow of current made b an induction coil or a capacitor.

$eactance &1nductive(: The characteristic of a coil# when connected to alternating current# whichcauses the current to lag the voltage in time phase. The current wave reaches its pea' later than thevoltage wave reaches its pea'.

$ectification: esignates the process b which electric energ is transferred from an alternatingcurrent (AC) to a direct current (C) circuit.

$ectifier: An electronic circuit which converts alternating current into direct current.

$eed Critical Frequenc+: -otational elements generate natural resonance frequencies which is afunction of shaft stiffness# mounting# and environment conditions (i.e.# vibration from equipment nearb).Hertical motors are affected more b this condition because of mounting at one end with the other endfree to move. /nder normal operating conditions with the motor operating at rated speed# the resonantfrequencies is not a concern. owever# inverter applications changes the base speed which affects themotor harmonics and will give an unstable resonance or vibration condition. To correct for potentialoperation in a critical speed zone# pump manufacturers can ma'e their discharge heads either stiff orloose.

$egeneration: The characteristic of a motor to act as a generator when the CF7 is larger than thedriveBs applied voltage (C drives) or when the rotorBs snchronous frequenc is greater than theapplied frequenc (AC drives).

$egeneration )ra-ing: The technique of slowing or stopping a drive b regeneration.

$egeneration Control: A regeneration drive contains the inherent capabilit and&or power semiconductors to control the flow of power to the motor and from the motor bac' to the power suppl.


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$egulation: The abilit of a control sstem to hold speed once it has been set. -egulation is given inpercentages of either base speed or set speed. -egulation is rated upon two separate sets ofconditions:

6. Speed $egulation , is the percentage of speed change with a defined change in load#assuming all other parameters to be constant.

>. "ine $egulation , is the percentage of speed change with a given line voltage change#assuming all other parameters to be constant.

$ela+: An electricall controlled device that causes electrical contacts to change status. ,pen contactswill close and closed contacts will open when rated voltage is applied to the coil of the rela.

$eluctance: The characteristic of a magnetic material which resists the flow of magnetic lines of forcethrough it.

$emote Control: -emote Control is a control function which provides for initiation or change of acontrol function from a remote point.

$eset: To reset is to restore a mechanism# storage or device to a prescribed state.

$esistance: The degree of obstacle presented b a material to the flow of electric current is 'nown asresistance and is measured in ohms.

$esilient Mounting: A suspension sstem or cushioned mounting designed to reduce the transmissionof normal motor noise and vibration to the mounting surface.

$esolution: The smallest distinguishable increment into which a quantit can be divided (e.g.# positionor shaft speed). %t is also the degree to which nearl equal values of a quantit can be discriminated. or encoders# it is the number of unique electricall identified positions occurring in 4D5 degrees of inputshaft rotation.

$esponse Time: The time required# following the initiation of a specified stimulus to a sstem# for anoutput going in the direction of necessar corrective action to first reach a specified value.

$eversing: Changing the direction of rotation of the motor armature or rotor. A C motor is reversed b

changing the polarit of the field or the armature# but not both. An AC motor is reversed b reversing theconnections of one leg on the three phase power line or b reversing the leads on a single phase powerline.

$everse Torque: A torque created b harmonics in a three phase motor and often resulting in a motorrunning at a reduced speed. ormall the forces of the revolving field all rotate in the same direction butan improperl designed motor can cause counter rotating harmonic fields that e!ceed the strength of theforward field at some specific speed. This speed ma be zero -+7 or some speed below the ratedvalue. This phenomenon is quite common in redesigns of motors to 65 poles or more.

$eversing: Changing the direction of rotation of the motor armature or rotor. A C motor is reversed bchanging the polarit of the field or the armature# but not both. An AC motor is reversed b reversing theconnections of one leg on the three phase power line# or b reversing the leads on a single phase power line.

$otation &$ot'(: irection in which shaft rotates:

6. C* J cloc'wise

>. CC* J countercloc'wise

4. -ev (C*&CC*) J reversible or bidirectional rotation which can be changed.

$otor: The rotating member of an induction motor with a shaft. Current is normall induced in the rotorwhich reacts with the magnetic field produced b the stator to produce torque and rotation.

$unning Torque: Also called stable torque# or equilibrium torque. A term loosel used meaningavailable torque at full (rated) speed# as opposed to starting torque.


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Saddle Torque: A torque developed# usuall well below rated speed# that is much less than normaltorque e!pected at that point. ,n the torque curve it creates a depression or Isaddle$ and thus the name. Also called the Icusp$ of the curve.

Salient Pole: A motor has salient poles when its stator or field poles are concentrated in to confinedarcs and the winding is wrapped around them (as opposed to distributing them in series of slots).

Sc!ematic Diagram &0lementar+ Diagram(: A schematic or elementar diagram is one that shows allcircuits devices of a controller. The diagram does not show the phsical arrangement of the devices orthe actual wiring to the devices.

Screens: 6&8inch mesh that covers the openings on open enclosure motors to 'eep rodents and othervermin from entering the motor cavit.

Seals , Double "ip: A rubber shaft seal to 'eep contaminants such as oil# water and dust from enteringthe bearing cavit.

Seals , Double Sealed )earings: earings which have seals on both sides to 'eep the lubricant insidethe bearing housing and 'eep out contaminants.

Seals , "ab+rint!: A nonfriction seal with a close fit of man turns which protects the bearing cavit

from contaminants which can cause bearing failure.

Seals , Taconite: Seals which provide a seal so tight as to filter out iron ore (one of the finest dusts)from entering the bearing cavit.

Secondar+ 9inding: The secondar winding of a motor is a winding which is not connected to thepower source# but which carries current induced in it through its magnetic lin'age with the primarwinding.

Self,$elease Coupling: A special feature of vertical hollow shaft motors which permits free spinning ofthe shaft while the pump water is receding without the pump shaft disengaging from the motor.

Semiconductor: A material# usuall silicon or germanium# which permits limited current flow.

Service Deviation: See operating&Service eviation.

Service Factor &SF(: A multiplier which# when applied to the rated horsepower# indicates a permissiblehorsepower loading at rated voltage and frequenc. 7otors rated over 6.5 S have more than normalmargin# and are used where unusual conditions such as occasional high or low voltage# momentaroverloads# etc.# are li'el to occur.Service Factor , Gear: A method of classifing loads and sizing gear reducers based on severit ofload. The service factor for gear applications is determined b A37A and is contingent on the dut ofthe gear bo!.

Service Factor , Motor: A multiplier which# when applied to the rated horsepower# indicates apermissible horsepower loading at the rated voltage and frequenc. The service factor advises howmuch e!tra horsepower the motor is capable of handling. or e!ample# a 65 hp motor with 6.6? servicefactor can operate to 66.?5 horsepower.

Service of a Controller: The service of a controller is the specific application in which the controller isto be used; for e!ample:

6. 3eneral purpose.

>. efinite purpose.6.Crane and hoist.>. Flevator.4. 7achine tool (rill).

Set Speed: The desired operating speed.

Severe Dut+: A totall enclosed motor with e!tra protection (for e!ample: shaft slinger# gas'etedterminal bo!N) to resist entr of contaminants. /sed in e!tra dirt# damp or other nonhazardous

contaminated environments.S!aft $unout: Term used to advise how must shaft pla there is at the end of the shaft e!tension inrelation to the flange of the motor.


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S!oc- "oad: The load seen b a clutch# bra'e# or motor in a sstem which transmits high pea' loads.This tpe of load is present in crushers# separators# grinders# conveors# winches# and cranes.

S!ort,Circuit: A defect in a winding which causes part of the normal electrical circuit to be bpassed.This frequentl results in reducing the resistance of impedance to such an e!tent as to causeoverheating of the winding# and subsequent burnout.

S!ort S!aft Motor: F7A standard 736 defines shaft length as the dimensions A# or the distancefrom the face# flange or base of the machine to the end of the shaft. %n a F7A tpe TS frame a shorterthan standard shaft e!tension is defined. This is usuall used when the motor is direct connected to theload via couplings and no overhung load is encountered.

Silicon Controlled $ectifier &SC$(: A solid state switch# sometimes referred to as a thristor. The SC-has an anode# cathode and control rectification since it can be turned on at will. The SC- can rapidlswitch large currents at high voltages. %t is small sizes and low in weight.

Si. Step 1nverter: An old inverter design in which the outgoing produced wave ta'es the form of si!steps# three up and three down.

S-e: Arrangement of laminations on a rotor or armature to provide a slight diagonal pattern of theirslots with respect to the shaft a!is. This pattern helps to eliminate low speed cogging effects in an

armature# minimizes induced vibration in a rotor# and minimizes harmonic stra currents.

S-eing: -efers to time dela or offset between an two signals in relation to each other.

Slaving: A method of connecting controllers in cascade (series) or parallel. A number of slave units canbe utilized# each running a drive at a different speed. *hen the manuall operated master controllercalls for a speed change# the slave units will respond in proportion# maintaining the speed ratiosbetween them.

Sleing: An incremental motion of the motor shaft or machine table from one position to another atma!imum speed without losing position control.

Slinger: A device on the shaft or rubbing on it that prevents entrance of abrasive material into thebearing. Also the washerli'e attachment to a shaft or part of the shaft that prevents oil from lea'ing intothe motor or out of the bearing.

Slip: The difference between the speed of the rotating magnetic field (which is alwas snchronous) andthe rotor in a nonsnchronous induction motor is 'nown as slip and is e!pressed as a percentage of asnchronous speed. Slip generall increases with an increase in load.

Slip Compensation: 7ethod of increasing the speed reference to the speed regulator circuit# based onthe value of motor torque# to maintain motor speed as the load on the motor changes.

Slip $ing: A conductor band mounted on an armature and insulated from it. A brush slides on the bandas the armature rotates. The function of the slip ring sstem is essentiall the same as a commutatorand brushes. Slip rings are also used to transmit current from the armature in a generator application.

Slip Speed: The speed difference between speed at an load and the snchronous speed.

Snoma-ing Motor: A specialized motor design for use in snowma'ing applications.

Space 4eater: 7otor accessor used to prevent moisture condensation in the motor during periods ofrest. *hen the motor is not operational# the space heater is energized to 'eep the motor temperature 65degrees above ambient.

Special Purpose Motor: A motor with special operating characteristics# special mechanicalconstruction# or both# designed for a particular application and not falling within the definition of ageneral purpose or definite purpose motor as defined b F7A.

Speed $ange: The minimum and ma!imum speeds at which a motor must operate under constant orvariable torque load condition. A ?5:6 speed range for a motor with top speed of 6L55 -+7 means themotor must operate as low as 4D -+7 and still maintain regulation within specifications.

Speed $egulation: The numerical measure in percent of how accuratel the motor speed can bemaintained. %t is the percentage of change in speed between no load and full load.


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Sp!erical $oller )earing: A special bearing design used for e!tended l ife or higher thrust whendesigns merit. This bearing will ta'e some radial load# but onl if thrust is applied at all times. Sphericalroller bearings# provided on /.S. 7,T,-S1 brand products# emplos sprig loading to ensure thebearing will not be damaged during starting and momentar upthrust conditions. These springs push upagainst the lower the lower race so the lower race is 'ept in contact. Since the spring pressure ma beseveral thousand pounds# a considerable load is imposed on the guide bearing during startup. Caremust be ta'en not to specif life factors that would cause bearing failures due to insufficient load during

normal operation.

Stabilit+: The abilit of a drive to operate a motor at constant speed (under varing load) without"hunting (alternatel speeding up and slowing down). %t is related to the characteristics of the load beingdriven and the electrical time constants of the driveBs regulator circuits.

Stable Torque: The torque of a motor is stable if the motor torque required for a load never e!ceeds


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Starting Torque: The torque e!erted b the motor during the starting period (a function of speed orslip).

Starting *ariable Speed Drive: %n this method# a variable speed drive (H) is installed between themotor and the driven load. This drive ma be an edd current clutch or fluid clutch (sometimes calledfluid coupling). /se of such a drive allows the motor to accelerate without accelerating the driven load. After the motor is ramped up to speed# then the load is brought up to operating speed.

Starting , 9+e Start5Delta $un: This method is actuall reduced voltage# but is accomplished bchanging the motor phase connections such that a winding that is designed to run with phase voltageequal to line voltage on delta connection is we connected for starting to put less than line voltage oneach phase.

Stator: That part of an induction motor$s magnetic structure which does not rotate. %t usuall containsthe primar winding.

Stead+ )us!ing: An option to vertical hollowshaft motors which enable the motor to give impression ofoperating as a solid shaft motor.

Stiffness: The abilit of a device to resist deviation due to load change.

Stopping , Counter Torque )ra-ing for $everse,$unning "oads: A form of reversing used in woundrotor motors. (*ound rotor motors are not part of the /.S. 7,T,-S1 brand product line.)

Stopping , DC D+namic )ra-ing: A form of bra'ing and stopping the motor which does not causerotation is reverse is to circulate direct current in the stator windings. This sets up a magnetic field that isstationar and tends to oppose the motion of the squirrelcage through the field. The speedtorque curvefor this situation is l i'e that for normal running# e!cept that the curve starts at snchronous speed andgoes toward a pea' torque near zero speed.

Stopping , 0dd+,Current )ra-ing: An electrical method of slowing a machine or load. Similar inprinciple to the C dnamic bra'ing of a squirrel cage motor. Stationar magnetic coils set up acontrollable magnetic field throughout which a conducting disc or clinder can turn. This disc or clinderis coupled mechanicall to the shaft that is to be bra'es. *hen it turns through the magnetic field# eddcurrents are generated and these cause a drag on the rotating shaft# =ust as a torque is set up in a

squirrelcage when currents flow in its shortcircuited conductors.

Stopping , Mec!anical )ra-ing: 7echanical bra'es are either disc tpe or shoe (or drum) tpe.Commonl# the shoes are raised from the wheel b an electromagnet and are set b a spring when themagnet is deengerized.

Stopping , Plugging: A tpe of motor bra'ing provided b reversing either voltage polarit or phasesequence so that the motor develops a countertorque which e!erts a retarding force to bra'e the motor.

Submersible Motor: A motor whose housing and terminal bo! is designed so that the motor can rununder water (or another allowable liquid) completel submerged at a temperature of water not above>?9 C.

Surge: A transient wave of current# voltage# or power in the electric circuit. 3ote: A transient has a highrate of change of current or voltage in the sstem.

Surge Protection: The process of absorbing and clipping voltage transients on an incoming AC line orcontrol circuit. 7,Hs (7etal ,!ide Haristors) and speciall designed -C (-esistorcapacitor) networ'sare usuall used to accomplish this.

Sitc!: A switch is a device for opening and closing or for changing the connections of acircuit. 3ote: A switch is understood to be manuall operated unless otherwise stated.

S+nc!ronous Speed: The speed of an AC induction motorBs rotating magnetic field. %t is determined bthe frequenc applied to the stator and the number of magnetic poles present in each phase of thestator windings. 7athematicall it is e!pressed as Speed (-+7) J 6>5 ! Applied requenc (z) &umber of +oles +er +hase.

S+stem 0fficienc+: The ratio of the mechanical power supplied to load to the total input power under

specified operating conditions. The input power includes requirements for au!iliar functions# such asmotor field# phase control# switching equipment# overload protection# and fans.


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Tac!ometer: A small generator normall used as a speed sensing device.

Tac!ometer Generator &Tac!(: A generator# mechanicall coupled to a rotating machine whosefunction is to generate a voltage# the magnitude or frequenc of which is used either to determine thespeed of rotation of the common shaft or to suppl a signal to a control circuit to provide speedregulation.

Temperature Codes: %n hazardous location motors# the temperature code is assigned b the ationalFlectrical Code (FC) to group together flammable liquids# vapors# dusts# and flings into groups withsimilar flashpoints.

Temperature/ 1gnition: %n hazardous location motors# the temperature at which once attained will causean e!plosion to occur in the volatile environment.

Temperature $ise: The measurable rise above the ambient temperature at which the full loaded motor operates. This temperature rise is the result of the heat losses in the stator winding# core# and rotor. ,nmost motors# manufacturers have replaced the -ise rating on the motor nameplate with a listing of the Ambient temperature rating# insulation class and service factor.Temperature/ #ltimate: The highest temperature of an spot to which a specific class of insulatingmaterials can be continuousl sub=ected without mar'ed decrease in the sstem$s designed life.

Terminal )loc-s or Strips: An accessor available to titan frame motors which fits into the conduit bo!and provides a means to group terminating leads from accessories separatel from the main leads.

Test , Complete 1nitial: A motor test which consists of full load heat run# percent slip# no load current#full load current# loc'ed rotor current# loc'ed rotor torque# brea'down torque (calculated)# efficienc andpower factor at 655@#


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>. 7anual -eset (7an.) E An e!ternal button must be pushed to restore power to motor. +referredwhere une!pected restarting would be hazardous# as on saws# conveors# compressors# etc.

4. %mpedance (%mp.) or %mpedance +rotected E 7otor is designed so that it will not burn out inless than 6? das under loc'ed rotor (stalled) conditions# in accordance with /2 standard o.?6K.

T!ermal Protector/ 9inding , T!erma,Sentr+: A complete thermal protection sstem for /.S.7,T,-S1 brand products for windings# protecting the motor from running overloads. %t will also protectthe motor from abnormall high ambient temperatures# voltage unbalance# high or low voltage#ventilation failure and single phasing. %t consists of three thermistors# solid state control for mounting inthe customer supplied panel# with 4 amps control circuit capacit.

T!ermal Protector/ 9inding , T!ermistors: A nonlinear resistance temperature detector made fromsemiconductor material. There are two general tpes# positive temperature coefficient (+TC) which hasa resistance that increases with increasing temperature# and negative temperature coefficient (TC) thathas a resistance that decreases with increasing temperature. Standard on /.S. 7,T,-S1 brandproducts is +TC. 2ines should not e!ceed ?5 ohms.

T!ermal Protector/ 9inding , T!ermocouples: A pair of two dissimilar materials which generates aminute voltage in proportion to its temperature. Such devices ma be used as a signal source inindicating instruments and control equipment.

T!ermal Protector/ 9inding , T!ermostats: Snap action# bimetallic# temperature actuate switchesinstalled in the connection endturns of the motor winding. Their purpose is to activate a warning deviceor shutdown the motor upon e!cessive winding temperatures.

T!ermal Protector/ 9inding , 9inding $TDs: +recision# wirewound resistors with a 'nowntemperatureresistance characteristic. -ecognized for their accurac# the -Ts resistance increaseswith temperature rise in a 'nown and highl repeatable manner. > -Ts per phase&D per motor arestandard offerings on /.S. 7,T,-S1 brand products.

T!ermistor: A nonlinear resistance temperature detector made from semiconductor material. Thethermistor trip point is defined as the point where resistance suddenl rises or falls depending on thetpe of thermistor. %t is usuall used with a solid state controller that monitors the thermistor resistanceand performs a preprogrammed f unction at the thermistor trip point. Thermistors are available with a

multitude of preset nonad=ustable trip points. This tpe of temperature detection device is used in theTF-7ASFT-0 motor protection device.

T!ermocouple: A =unction of two dissimilar materials which generates a minute voltage in proportion toits temperature. Such devices ma be used as a signal source in indicating instruments and controlequipment.

T!ermostat: A temperature sensing device# with e!ternal leads# which must be properl connected tothe control circuit of the motor controller to limit the frame or winding temperature of the motor.T!read Speed: A fi!ed low speed# usuall ad=ustable# supplied to provide a convenient method forloading and threading machines. 7a also be called a preset speed.

T!rust: %n vertical motors an unusuall heav weight or load in one or both directions.

T!rust )earing: A specialized bearing design to handle heav weights or loads in one or bothdirections.

T!+ristor: A three =unction semiconductor device that can be switched from the off state to the on stateor vice versa.

Time Dela+: A time interval that is purposel introduced in the performance of a function.

Torque: A turning force applied to a shaft# tending to cause rotation. Torque is normall measure inpound&feet and is equal to the force applied times the radius through which it acts.

Torque/ )rea-don: The ma!imum torque the motor will develop with rated voltage applied at ratedfrequenc without an abrupt drop in speed. /suall e!pressed as a percentage of fullload torque.

Torque/ Constant: An application which requires the same torque at all operating speeds. orsepower

varies directl with the speed. F!amples of constant torque applications include conveors# hoists# andpositive displacement pumps.


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Torque Control: 7otor torque is regulated instead of motor speed.

Torque/ Full,"oad: The torque necessar to produce its rated horsepower at fullload speed.

Torque/ "oc-ed,$otor: The torque the motor will deve

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Electric Motor Terminology

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