Poly Phase Induction Motor Question & AnswersSeptember 27, 2021 By Wat Electrical Leave a Comment This article lists 100 Poly Phase Induction Motor MCQs for Engineering Students. All the Poly Phase Induction Motor Questions & Answers given below includes solution and link wherever possible to the relevant topic.The induction motor has two main parts they are stator and rotor, the stator is a three coil winding. The stator produces a rotating magnetic field when a three-phase current passes through the winding. The induction motors are widely used as industrial drives because they are rugged, economical, and reliable.The word poly means two or many and the word phase means winding, the circuit which has more than two windings then the circuit is said to be a polyphase circuit. In polyphase windings, it is essential that the waveforms of the phase electromotive forces are identical and the frequency of the phase electromotive forces are equal. 1). The AC motors are categorized into _____________ typesOneTwoThreeFourHintThe AC motors are categorized into three types they are polyphase, universal, and single-phaseRead more about AC Motor 2). How many parts does the three-phase induction motor consist of?OneTwoThreeFourHintThe three-phase induction motor consists of two parts they are rotor and stator Read more about Three Phase Induction Motor 3). What are the main parts of the stator?Stator windingStator coreOuter frameAll of the aboveHintThe stator winding, stator core, and outer frame are the main parts of the stator 4). The cost of the wound motor is ____________LessVery lessMoreVery expensiveHintThe cost of the wound motor is more compared to other motors 5). The size of the wound motor is ____________SmallVery smallLargeVery largeHintThe size of the wound motor is large 6). What is the standard form of RMF?Rotating Magnetic FieldRotor Magnetic FieldRotating or Rotor Magnetic fieldNone of the aboveHintThe standard form of RMF is Rotating Magnetic Field 7). What is the standard form of LIM?Linear Induction MotorNon-linear Induction MotorLine Induction MotorNone of the aboveHintThe standard form of LIM is Linear Induction Motor 8). The induction motor frame is made up of ___________Cast ironSiliconAluminumNone of the aboveHintThe induction motor frame is made up of cast iron 9). The induction motor shaft is made of _________SilverCopperCarbon steelNone of the aboveHintThe induction motor shaft is made of carbon steel 10). The slip is around _____________ in medium size induction motors2%3%4%HintThe slip is around four percent in medium-size induction motors 11). Which one of the materials is used to made slip rings?CopperPhospor bronzeSilverNone of the aboveHintThe slip rings are made of phosphor bronze 12). ___________ are the types of poly-phase induction motorSingle-phaseUniversalWound rotor & squirrel cageAll of the aboveHintThe wound rotor and squirrel cage machines are two types of poly-phase induction motor 13). The shaft speed parameter is defined as a ratio of _____________Shaft speed/synchronous speedShaft speed+synchronous speedShaft speed*synchronous speedNone of the aboveHintThe shaft speed parameter is defined as a ratio of shaft speed divided by the synchronous speed 14). The ratio of synchronous speed divided by a rotor speed is known as ___________ speedSlipShaftSynchronousNone of the aboveHintThe ratio of synchronous speed divided by a rotor speed is known as slip speed 15). Which one of the following is the correct formula for synchronous speed?)(10*frequency of the system)/P(20*frequency of the system)/P(120*frequency of the system)/PNone of the aboveHintThe formula for synchronous speed is given by (120*frequency of the system)/P 16). Which one of the following is a correct formula a motor slip?(Speed of magnetic field-mechanical shaft speed)/speed of magnetic field*100Speed of magnetic field/speed of magnetic field*100Mechanical shaft speed/speed of magnetic field*100None of the aboveHintThe formula for motor slip is given by (Speed of magnetic field-mechanical shaft speed)/speed of magnetic field*100 17). The induced torque is defined as a ratio of ____________Power/speedSpeed/powerVoltage/CurrentNone of the aboveHintThe induced torque is defined as a ratio of power in KW divided by the speed in r/min 18). The induction motor rotor runs at _____________ speedSynchronousAsynchronousBelow synchronousNone of the aboveHintThe induction motor rotor runs at below the synchronous speed 19). The induction motor torque is _____________ proportional to the slipDirectlyInverselyEither directly or inverselyNone of the aboveHintThe induction motor torque is directly proportional to the slip 20). The percentage slip in an induction motor depends on ___________ in motorFrequencyVoltageCopper lossesNone of the aboveHintThe percentage slip in an induction motor depends on copper losses in the motor 21). If the air gap is increased in an induction motor, the power factor will be ____________Very highHighLowNone of the aboveHintIf the air gap is increased in an induction motor, the power factor will be low 22). What are the disadvantages of LIM motor?Power factor is very lowMaintenance is not easyCapital cost is very highAll of the aboveHintThe disadvantages of LIM motor are maintenance is not easy, power factor is very low, and capital cost is very high 23). What are the advantages of LIM motors?SimpleGives higher speedMore efficientAll of the aboveHintThe linear induction motors are simple, more efficient, and has a lower initial cost 24). The starting torque is high in ____________ induction motorSquirrel cageSlip ringBoth a and bNone of the aboveHintThe starting torque is high in slip ring induction motor 25). The speed control by rotor resistance is possible in ___________ induction motorSquirrel cageSlip ringBoth a and bNone of the aboveHintThe speed control by rotor resistance is possible in slip ring induction motorPolyphase Induction Motor MCQs for Exams 26). Which one of the following is a type of stator?Autotransformer, star-deltaRotor resistanceDirect on-line, stator resistanceAll of the aboveHintThe autotransformer stator, stator resistance, DOL, rotor resistance, and star-delta are the types of stators 27). What are the advantages of stator?CheapSimple in constructionBoth a and bNone of the aboveHintThe stators are cheap and simple in construction 28). Which one of the following stator costs is more?AutotransformerStar deltaDirect on lineAll of the aboveHintThe auto-transformer stator cost is more compare to star-delta and DOL stators 29). Which one of the following stators doesn’t decrease the starting current?AutotransformerStar deltaDirect on lineAll of the aboveHintThe direct on-line stator doesn’t decrease the starting current 30). The direct on-line stator is used up to _____________ HPOneTwoFourFiveHintThe direct on-line stator is used up to 5 HP 31). Which one of the following stators used above 20 HP?AutotransformerStar deltaDirect on lineAll of the aboveHintThe auto-transformer stator used above 20 HP 32). Which one of the following stators is very cheap?AutotransformerStar deltaDirect on lineAll of the aboveHintThe direct on-line stator is very cheap compare to other stators 33). What are the advantages of auto-transformer?High-efficiencyCopper losses are lessVA rating is moreAll of the aboveHintTh auto-transformers have high efficiency, more VA rating, and has fewer copper losses 34). Which one of the following transformers is can’t be used as variac?Two windingSingleBoth a and bNone of the aboveHintThe two winding transformers is can’t be used as variac 35). Which one of the following transformers has more KVA rating?Two windingAuto windingBoth a and bNone of the aboveHintThe auto-transformer has more KVA rating compare to two winding transformer 36). Which one of the following costs is slightly higher?Squirrel cageSlip ringBoth a and bNone of the aboveHintThe slip ring cost is slightly higher compared to squirrel induction motor 37). The leakage and resistance values are more in _____________ transformerTwo windingAuto windingBoth a and bNone of the aboveHintThe leakage and resistance values are more in two winding transformer 38). How many windings do the two winding transformers have?OneTwoThreeFourHintThe two winding transformers have two windings 39). The wound or slip ring rotor is used for ______________ElevatorsCranesLiftsAll of the aboveHintThe wound or slip ring rotor is used for elevators, cranes, lifts, etc 40). The squirrel cage rotor is used for ______________Water pumpslathesFansAll of the aboveHintThe squirrel cage rotor is used for water pumps, lathes, fans, etc 41). The speed control by rotor resistance is not possible in ______________ rotorWoundSquirrel cageBoth a and bNone of the aboveHintThe speed control by rotor resistance is not possible in squirrel cage rotor 42). In squirrel cage rotor, the rotor copper losses are _____________LessMoreVery lessNone of the aboveHintIn squirrel cage rotor, the rotor copper losses are less 43). The difference between rotor speed and synchronous speed of RMF is known as ______________Synchronous speedSlip speedRotor speedNone of the aboveHintThe difference between rotor speed and synchronous speed of RMF is known as slip speed 44). Which one of the following system costs is high?Brushless DC motorBrushed DC motorInduction motorAll of the aboveHintIn brushless DC motor, the system cost is high because of external controller requirement 45). In which one of the following motors the controller is required?Brushless DC motorBrushed DC motorInduction motorAll of the aboveHintIn brushless DC motor, the controller is required to control the communication sequence whereas the controller is not required in brushed DC and induction motor 46). In which one of the following motors the speed range is low?Brushless DC motorBrushed DC motorInduction motorAll of the aboveHintIn an induction motor, the speed range is low, whereas in a brushless DC motor the speed range is high 47). Which one of the following has less starting current?Squirrel cageSlip ringBoth a and bNone of the aboveHintThe slip ring induction motor has less starting current compare to the squirrel induction motor 48). How many windings does auto-transformer have?OneTwoThreeFourHintThe auto-transformer has only one winding whereas the two winding transformers have two 49). The copper losses are more in ___________ transformerTwo windingAuto windingBoth a and bNone of the aboveHintThe copper losses are more in two winding transformers whereas in autotransformer the copper losses are less 50). The size and cost is high in _______________ transformerTwo windingAuto windingBoth a and bNone of the aboveHintThe size and cost is high in two winding transformerPolyphase Induction Motor Important MCQs 51). Which one of the following transformers has less efficiency?Two windingAuto windingBoth a and bNone of the aboveHintThe two winding transformers has less efficiency whereas in autotransformer the efficiency is high 52). In which one the following motor the special starting circuit is required?Brushless DC motorBrushed DC motorInduction motorAll of the aboveHintIn induction motor the special starting circuit is required 53). The motor control is categorized into _____________types based on the functions servedMotor protectionSpeed controlTorque controlAll of the aboveHintThe motor control is categorized into three types based on the functions served they are motor protection, speed control, and torque control 54). What is the standard form of BLDC?Brushed DC MotorBrush DC MotorBrushless DC MotorNone of the aboveHintThe standard form of BLDC is Brushless DC Motor 55). What is the standard form of CPAP?Continuous Positive Airway PressureContinuous Pressure Airway PositiveContinuous Pressure Airway PressureNone of the aboveHintThe standard form of CPAP is Continuous Positive Airway Pressure 56). Which one of the following motors is a type of brushless DC motor?Interior permanent magnet typeShunt motorSeries motorAll of the aboveHintThe interior permanent magnet type is one type of brushless DC motor 57). Which one of the following is not a type of DC motor?Permanent magnet DC motorWinding filed DC motorSynchronous motorAll of the aboveHintThe synchronous motor is not a type of DC motor 58). Which one of the following motors has a fast dynamic response?VR motorPM motorBoth a and bNone of the aboveHintThe VR motor has a fast dynamic response whereas the PM motors have a slow dynamic response 59). Which one of the following motors doesn’t have detent torque?VR motorPM motorBoth a and bNone of the aboveHintThe VR motor doesn’t have detent torque whereas in PM motors the detent torque is present 60). Which one of the following motors has a high maximum stepping rate?PM motorVR motorBoth a andNone of the aboveHintThe VR motor have high maximum stepping rate i.e around 1200 pulse per second 61). Which one of the following motors has a high step angle?VR motorPM motorBoth a and bNone of the aboveHintThe VR motors have high step angles whereas in PM motor very small step angle is possible 62). _________________ are the modes of operation of variable reluctance stepper motors1 phase ON and 2 phase ON modeHalf step operationMicro-steppingAll of the aboveHintThe 1 phase ON, 2 phase ON mode, half step operation, and micro-stepping are the modes of operation of variable reluctance stepper motors 63). The low inertia DC motors are categorized into _______________OneTwoThreeFourHintThe low inertia DC motors are categorized into two types they are shell-type motor and printed circuit motor 64). Which one of the following is denoted by CX?Control transmitterControl receiverControl transformerControl differentialHintThe control transmitter is denoted by CX, it is a type of synchro transmitter 65). Which one of the following is denoted by CD?Control transmitterControl receiverControl transformerControl differentialHintThe control differential is denoted by CD, it is a type of synchro differential 66). The synchros are used in servomechanism for _____________Error detectionTorque transmissionSubtracting and adding rotary anglesAll of the aboveHintThe synchros are used in servomechanism for error detection, torque transmission, subtracting and adding rotary angles 67). What is the standard form of SR motor?Switched ReluctanceSimple ReluctanceSwitched ResistanceNone of the aboveHintThe standard form of SR motor is Switched Reluctance motor 68). The switched reluctance motor has power rating up to _____________10KW40KW20KW75KWHintThe switched reluctance motor has a power rating of up to 75KW 69). The variable reluctance motor has ______________Low power ratingLower efficiencyBoth a and bNone of the aboveHintThe variable reluctance motor has low a power rating and lower efficiency 70). What is the standard form of PMBL?Permanent Magnet Brushed MachinesPermanent Magnet Brush Less MachinesPermanent Magnet MachinesNone of the aboveHintThe standard form of PMBL is Permanent Magnet Brush Less Machines 71). Which one of the following is a type of AC motor?Commutator motorSynchronous motorInduction motorAll of the aboveHintThe commutator motor, synchronous motor, and induction motor are the type of AC motors 72). The stepping motor is categorized into _________________OneTwoThreeFourHintThe stepping motor is categorized into three types they are VR type, PM type, and hybrid type stepping motors 73). Which one of the following motors is not a type of induction motor?Eddy currentSingle phaseWound rotor typeReluctance motorHintThe reluctance motor is not a type of induction motor, it is a type of synchronous motor 74). The winding field DC motors are categorized into _______________OneTwoThreeFourHintThe winding field DC motors are categorized into three types they are shunt motor, series motor, and separate field motor 75). The surface permanent magnet type motor is a _______________ motorCommutator motorSynchronous motorInduction motorBrushless DC motorHintThe surface permanent magnet type motor is a brushless DC motorPolyphase Induction Motor MCQs with Hints 76). Which one of the following is denoted by CR?Control transmitterControl receiverControl transformerControl differentialHintThe control receiver is denoted by CR, it is a type of synchro receiver 77). Which one of the following motors is not a self-starting motor?Synchronous motorInduction motorBoth a and bNone of the aboveHintThe synchronous motor is not a self-starting motor 78). The embedded magnet rotor is used in _______________FansPumpsIrrigationAll of the aboveHintThe embedded magnet rotor is used in fans, pumps, irrigation, etc 79). What are the components of the motor?Rotor, bearingStator, bracket or endplateLead wireAll of the aboveHintThe rotor, bearing, stator, bracket or endplate, and lead wire are the components of motor 80). ___________________ are the type of motors classified by the principle of conversionElectromagnetic motorUltrasonic motorBoth a and bNone of the aboveHintThe electromagnetic motor and ultrasonic motors are the types of motors classified by the principle of conversion 81). ______________ are the methods to control the speed of induction motors from stator sidePole changingSupply voltage controlVariable frequency controlAll of the aboveHintThe speed of induction motors is controlled by the pole changing method, by variable frequency control, and by supply voltage control from the stator side 82). Which one of the following is denoted by CT?Control transmitterControl receiverControl transformerControl differentialHintThe control transformer is denoted by CT, it is a type of synchro transformer 83). ______________ are the methods to control the speed of induction motors from rotor sideSlip energy recoveryRotor resistance controlInjection of an EMF in the rotor circuitAll of the aboveHintThe speed of induction motors is controlled by the slip energy recovery method, by rotor resistance control, and by injection of an EMF in the rotor circuit from the rotor side 84). The variable frequency drive has ________________ sectionsConverterInverterDC busAll of the aboveHintThe variable frequency drive has converter section, inverter section, and DC bus sections 85). The variable frequency drives are used for ____________ the motorStartControlStopAll of the aboveHintThe variable frequency drives are used to stop, start, and also control the speed of the motor 86). Which one of the following has fewer energy savings?Soft starterVariable frequency driveBoth a and bNone of the aboveHintThe energy-saving is less in soft starter compare to VFD 87). ___________________ are the type of motors classified by the power supplyDC power supplySingle-phase or three-phase AC power supplyBoth a and bNone of the aboveHintThe DC power supply, single-phase, or three-phase AC power supply are the types of motors classified by the power supply 88). _____________ are the type of PM DC motors by armature typeSlotted typeCoreless typeSlotless typeAll of the aboveHintThe slotted type, coreless type, and slotless type are the type of PM DC motors by armature type 89). What is the standard form of IPM?Inferior Permanent MagnetInterior Permanent MagnetInsulated Permanent MagnetNone of the aboveHintThe standard form of IPM is Interior Permanent Magnet, it is a type of motor 90). The space requirement is more in _________________Soft starterVariable frequency driveBoth a and bNone of the aboveHintThe space requirement is more in variable frequency drive whereas the space requirement is less in the soft starter 91). Which one of the following starters is used in medium and low torque applications?Soft starterVariable frequency driveBoth a and bNone of the aboveHintThe soft starter is used in medium and low torque applications whereas the VFD used in high torque applications 92). What are the advantages of a DOL starter?Easy to troubleshootEasy to understandMost economical and cheapAll of the aboveHintThe DOL starters are easy to troubleshoot, easy to understand, most economical, and cheap 93). What are the advantages of disc motor?High-costSmooth rotation with zero coggingLow-costBoth b and cHintThe advantages of disc motor are low cost and smooth rotation with zero cogging 94). The disc motors are used in __________________ applicationsCD playersVCR playersRecord playersAll of the aboveHintThe disc motors are used in CD players, VCR players, record players, etc 95). The hysteresis motor is a type of ______________ motorCommutator motorSynchronous motorInduction motorBrushless DC motorHintThe hysteresis motor is a type of synchronous motor 96). What is the standard form of SPM?Surface Permanent MagnetSurface Permanent MachineSolid Permanent MagnetNone of the aboveHintThe standard form of SPM is Surface Permanent Magnet, it is a type of brushless DC motor 97). What are the disadvantages of DOL starters?High starting currentMechanically harshHigh starting torqueAll of the aboveHintThe DOL starter has a high starting current, high starting torque, and it is mechanically harsh 98). The direct on-line starter is suitable for _____________Conveyor beltsWater pumps cCompressorsAll of the aboveHintThe direct on-line starter is suitable for conveyor belts, water pumps, and compressors 99). What are the advantages of a star-delta starter?Good torque/ current performanceSimple and ruggedCheapAll of the aboveHintThe star-delta starter has good torque/current performance, and it is simple, cheap, and rugged 100). What are the applications of variable frequency drive?Cane carrier driveRaw juice pumpsInjection pumpsAll of the aboveHintThe variable frequency drive used in cane carrier drive, raw juice pumps, injection pumps, etc Time is Up! Time's up
Leave a Reply