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 _____________ types One Two Three Four HintThe AC motors are categorized into three types they are polyphase, universal, and single-phaseRead more about AC Motor2). How many parts does the three-phase induction motor consist of? One Two Three Four HintThe three-phase induction motor consists of two parts they are rotor and stator Read more about Three Phase Induction Motor3). What are the main parts of the stator? Stator winding Stator core Outer frame All of the above HintThe stator winding, stator core, and outer frame are the main parts of the stator 4). The cost of the wound motor is ____________ Less Very less More Very expensive HintThe cost of the wound motor is more compared to other motors5). The size of the wound motor is ____________ Small Very small Large Very large HintThe size of the wound motor is large6). What is the standard form of RMF? Rotating Magnetic Field Rotor Magnetic Field Rotating or Rotor Magnetic field None of the above HintThe standard form of RMF is Rotating Magnetic Field7). What is the standard form of LIM? Linear Induction Motor Non-linear Induction Motor Line Induction Motor None of the above HintThe standard form of LIM is Linear Induction Motor8). The induction motor frame is made up of ___________ Cast iron Silicon Aluminum None of the above HintThe induction motor frame is made up of cast iron9). The induction motor shaft is made of _________ Silver Copper Carbon steel None of the above HintThe induction motor shaft is made of carbon steel10). The slip is around _____________ in medium size induction motors <l% 2% 3% 4% HintThe slip is around four percent in medium-size induction motors11). Which one of the materials is used to made slip rings? Copper Phospor bronze Silver None of the above HintThe slip rings are made of phosphor bronze12). ___________ are the types of poly-phase induction motor Single-phase Universal Wound rotor & squirrel cage All of the above HintThe wound rotor and squirrel cage machines are two types of poly-phase induction motor13). The shaft speed parameter is defined as a ratio of _____________ Shaft speed/synchronous speed Shaft speed+synchronous speed Shaft speed*synchronous speed None of the above HintThe shaft speed parameter is defined as a ratio of shaft speed divided by the synchronous speed14). The ratio of synchronous speed divided by a rotor speed is known as ___________ speed Slip Shaft Synchronous None of the above HintThe ratio of synchronous speed divided by a rotor speed is known as slip speed15). 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)/P None of the above HintThe formula for synchronous speed is given by (120*frequency of the system)/P16). Which one of the following is a correct formula a motor slip? (Speed of magnetic field-mechanical shaft speed)/speed of magnetic field*100 Speed of magnetic field/speed of magnetic field*100 Mechanical shaft speed/speed of magnetic field*100 None of the above HintThe formula for motor slip is given by (Speed of magnetic field-mechanical shaft speed)/speed of magnetic field*10017). The induced torque is defined as a ratio of ____________ Power/speed Speed/power Voltage/Current None of the above HintThe induced torque is defined as a ratio of power in KW divided by the speed in r/min18). The induction motor rotor runs at _____________ speed Synchronous Asynchronous Below synchronous None of the above HintThe induction motor rotor runs at below the synchronous speed19). The induction motor torque is _____________ proportional to the slip Directly Inversely Either directly or inversely None of the above HintThe induction motor torque is directly proportional to the slip20). The percentage slip in an induction motor depends on ___________ in motor Frequency Voltage Copper losses None of the above HintThe percentage slip in an induction motor depends on copper losses in the motor21). If the air gap is increased in an induction motor, the power factor will be ____________ Very high High Low None of the above HintIf the air gap is increased in an induction motor, the power factor will be low22). What are the disadvantages of LIM motor? Power factor is very low Maintenance is not easy Capital cost is very high All of the above HintThe disadvantages of LIM motor are maintenance is not easy, power factor is very low, and capital cost is very high23). What are the advantages of LIM motors? Simple Gives higher speed More efficient All of the above HintThe linear induction motors are simple, more efficient, and has a lower initial cost24). The starting torque is high in ____________ induction motor Squirrel cage Slip ring Both a and b None of the above HintThe starting torque is high in slip ring induction motor25). The speed control by rotor resistance is possible in ___________ induction motor Squirrel cage Slip ring Both a and b None of the above HintThe speed control by rotor resistance is possible in slip ring induction motorPolyphase Induction Motor MCQs for Exams26). Which one of the following is a type of stator? Autotransformer, star-delta Rotor resistance Direct on-line, stator resistance All of the above HintThe autotransformer stator, stator resistance, DOL, rotor resistance, and star-delta are the types of stators27). What are the advantages of stator? Cheap Simple in construction Both a and b None of the above HintThe stators are cheap and simple in construction28). Which one of the following stator costs is more? Autotransformer Star delta Direct on line All of the above HintThe auto-transformer stator cost is more compare to star-delta and DOL stators29). Which one of the following stators doesn’t decrease the starting current? Autotransformer Star delta Direct on line All of the above HintThe direct on-line stator doesn’t decrease the starting current30). The direct on-line stator is used up to _____________ HP One Two Four Five HintThe direct on-line stator is used up to 5 HP31). Which one of the following stators used above 20 HP? Autotransformer Star delta Direct on line All of the above HintThe auto-transformer stator used above 20 HP32). Which one of the following stators is very cheap? Autotransformer Star delta Direct on line All of the above HintThe direct on-line stator is very cheap compare to other stators33). What are the advantages of auto-transformer? High-efficiency Copper losses are less VA rating is more All of the above HintTh auto-transformers have high efficiency, more VA rating, and has fewer copper losses34). Which one of the following transformers is can’t be used as variac? Two winding Single Both a and b None of the above HintThe two winding transformers is can’t be used as variac35). Which one of the following transformers has more KVA rating? Two winding Auto winding Both a and b None of the above HintThe auto-transformer has more KVA rating compare to two winding transformer36). Which one of the following costs is slightly higher? Squirrel cage Slip ring Both a and b None of the above HintThe slip ring cost is slightly higher compared to squirrel induction motor37). The leakage and resistance values are more in _____________ transformer Two winding Auto winding Both a and b None of the above HintThe leakage and resistance values are more in two winding transformer38). How many windings do the two winding transformers have? One Two Three Four HintThe two winding transformers have two windings 39). The wound or slip ring rotor is used for ______________ Elevators Cranes Lifts All of the above HintThe wound or slip ring rotor is used for elevators, cranes, lifts, etc40). The squirrel cage rotor is used for ______________ Water pumps lathes Fans All of the above HintThe squirrel cage rotor is used for water pumps, lathes, fans, etc41). The speed control by rotor resistance is not possible in ______________ rotor Wound Squirrel cage Both a and b None of the above HintThe speed control by rotor resistance is not possible in squirrel cage rotor42). In squirrel cage rotor, the rotor copper losses are _____________ Less More Very less None of the above HintIn squirrel cage rotor, the rotor copper losses are less43). The difference between rotor speed and synchronous speed of RMF is known as ______________ Synchronous speed Slip speed Rotor speed None of the above HintThe difference between rotor speed and synchronous speed of RMF is known as slip speed44). Which one of the following system costs is high? Brushless DC motor Brushed DC motor Induction motor All of the above HintIn brushless DC motor, the system cost is high because of external controller requirement45). In which one of the following motors the controller is required? Brushless DC motor Brushed DC motor Induction motor All of the above HintIn brushless DC motor, the controller is required to control the communication sequence whereas the controller is not required in brushed DC and induction motor46). In which one of the following motors the speed range is low? Brushless DC motor Brushed DC motor Induction motor All of the above HintIn an induction motor, the speed range is low, whereas in a brushless DC motor the speed range is high47). Which one of the following has less starting current? Squirrel cage Slip ring Both a and b None of the above HintThe slip ring induction motor has less starting current compare to the squirrel induction motor48). How many windings does auto-transformer have? One Two Three Four HintThe auto-transformer has only one winding whereas the two winding transformers have two 49). The copper losses are more in ___________ transformer Two winding Auto winding Both a and b None of the above HintThe copper losses are more in two winding transformers whereas in autotransformer the copper losses are less50). The size and cost is high in _______________ transformer Two winding Auto winding Both a and b None of the above HintThe size and cost is high in two winding transformerPolyphase Induction Motor Important MCQs51). Which one of the following transformers has less efficiency? Two winding Auto winding Both a and b None of the above HintThe two winding transformers has less efficiency whereas in autotransformer the efficiency is high52). In which one the following motor the special starting circuit is required? Brushless DC motor Brushed DC motor Induction motor All of the above HintIn induction motor the special starting circuit is required53). The motor control is categorized into _____________types based on the functions served Motor protection Speed control Torque control All of the above HintThe motor control is categorized into three types based on the functions served they are motor protection, speed control, and torque control54). What is the standard form of BLDC? Brushed DC Motor Brush DC Motor Brushless DC Motor None of the above HintThe standard form of BLDC is Brushless DC Motor55). What is the standard form of CPAP? Continuous Positive Airway Pressure Continuous Pressure Airway Positive Continuous Pressure Airway Pressure None of the above HintThe standard form of CPAP is Continuous Positive Airway Pressure56). Which one of the following motors is a type of brushless DC motor? Interior permanent magnet type Shunt motor Series motor All of the above HintThe interior permanent magnet type is one type of brushless DC motor57). Which one of the following is not a type of DC motor? Permanent magnet DC motor Winding filed DC motor Synchronous motor All of the above HintThe synchronous motor is not a type of DC motor58). Which one of the following motors has a fast dynamic response? VR motor PM motor Both a and b None of the above HintThe VR motor has a fast dynamic response whereas the PM motors have a slow dynamic response59). Which one of the following motors doesn’t have detent torque? VR motor PM motor Both a and b None of the above HintThe 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 motor VR motor Both a and None of the above HintThe VR motor have high maximum stepping rate i.e around 1200 pulse per second61). Which one of the following motors has a high step angle? VR motor PM motor Both a and b None of the above HintThe VR motors have high step angles whereas in PM motor very small step angle is possible62). _________________ are the modes of operation of variable reluctance stepper motors 1 phase ON and 2 phase ON mode Half step operation Micro-stepping All of the above HintThe 1 phase ON, 2 phase ON mode, half step operation, and micro-stepping are the modes of operation of variable reluctance stepper motors63). The low inertia DC motors are categorized into _______________ One Two Three Four HintThe low inertia DC motors are categorized into two types they are shell-type motor and printed circuit motor64). Which one of the following is denoted by CX? Control transmitter Control receiver Control transformer Control differential HintThe control transmitter is denoted by CX, it is a type of synchro transmitter65). Which one of the following is denoted by CD? Control transmitter Control receiver Control transformer Control differential HintThe control differential is denoted by CD, it is a type of synchro differential66). The synchros are used in servomechanism for _____________ Error detection Torque transmission Subtracting and adding rotary angles All of the above HintThe synchros are used in servomechanism for error detection, torque transmission, subtracting and adding rotary angles67). What is the standard form of SR motor? Switched Reluctance Simple Reluctance Switched Resistance None of the above HintThe standard form of SR motor is Switched Reluctance motor68). The switched reluctance motor has power rating up to _____________ 10KW 40KW 20KW 75KW HintThe switched reluctance motor has a power rating of up to 75KW69). The variable reluctance motor has ______________ Low power rating Lower efficiency Both a and b None of the above HintThe variable reluctance motor has low a power rating and lower efficiency70). What is the standard form of PMBL? Permanent Magnet Brushed Machines Permanent Magnet Brush Less Machines Permanent Magnet Machines None of the above HintThe standard form of PMBL is Permanent Magnet Brush Less Machines71). Which one of the following is a type of AC motor? Commutator motor Synchronous motor Induction motor All of the above HintThe commutator motor, synchronous motor, and induction motor are the type of AC motors72). The stepping motor is categorized into _________________ One Two Three Four HintThe stepping motor is categorized into three types they are VR type, PM type, and hybrid type stepping motors73). Which one of the following motors is not a type of induction motor? Eddy current Single phase Wound rotor type Reluctance motor HintThe reluctance motor is not a type of induction motor, it is a type of synchronous motor74). The winding field DC motors are categorized into _______________ One Two Three Four HintThe winding field DC motors are categorized into three types they are shunt motor, series motor, and separate field motor75). The surface permanent magnet type motor is a _______________ motor Commutator motor Synchronous motor Induction motor Brushless DC motor HintThe surface permanent magnet type motor is a brushless DC motorPolyphase Induction Motor MCQs with Hints76). Which one of the following is denoted by CR? Control transmitter Control receiver Control transformer Control differential HintThe control receiver is denoted by CR, it is a type of synchro receiver77). Which one of the following motors is not a self-starting motor? Synchronous motor Induction motor Both a and b None of the above HintThe synchronous motor is not a self-starting motor78). The embedded magnet rotor is used in _______________ Fans Pumps Irrigation All of the above HintThe embedded magnet rotor is used in fans, pumps, irrigation, etc79). What are the components of the motor? Rotor, bearing Stator, bracket or endplate Lead wire All of the above HintThe rotor, bearing, stator, bracket or endplate, and lead wire are the components of motor80). ___________________ are the type of motors classified by the principle of conversion Electromagnetic motor Ultrasonic motor Both a and b None of the above HintThe electromagnetic motor and ultrasonic motors are the types of motors classified by the principle of conversion81). ______________ are the methods to control the speed of induction motors from stator side Pole changing Supply voltage control Variable frequency control All of the above HintThe speed of induction motors is controlled by the pole changing method, by variable frequency control, and by supply voltage control from the stator side82). Which one of the following is denoted by CT? Control transmitter Control receiver Control transformer Control differential HintThe control transformer is denoted by CT, it is a type of synchro transformer83). ______________ are the methods to control the speed of induction motors from rotor side Slip energy recovery Rotor resistance control Injection of an EMF in the rotor circuit All of the above HintThe 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 side84). The variable frequency drive has ________________ sections Converter Inverter DC bus All of the above HintThe variable frequency drive has converter section, inverter section, and DC bus sections85). The variable frequency drives are used for ____________ the motor Start Control Stop All of the above HintThe variable frequency drives are used to stop, start, and also control the speed of the motor86). Which one of the following has fewer energy savings? Soft starter Variable frequency drive Both a and b None of the above HintThe energy-saving is less in soft starter compare to VFD87). ___________________ are the type of motors classified by the power supply DC power supply Single-phase or three-phase AC power supply Both a and b None of the above HintThe DC power supply, single-phase, or three-phase AC power supply are the types of motors classified by the power supply88). _____________ are the type of PM DC motors by armature type Slotted type Coreless type Slotless type All of the above HintThe slotted type, coreless type, and slotless type are the type of PM DC motors by armature type89). What is the standard form of IPM? Inferior Permanent Magnet Interior Permanent Magnet Insulated Permanent Magnet None of the above HintThe standard form of IPM is Interior Permanent Magnet, it is a type of motor90). The space requirement is more in _________________ Soft starter Variable frequency drive Both a and b None of the above HintThe space requirement is more in variable frequency drive whereas the space requirement is less in the soft starter91). Which one of the following starters is used in medium and low torque applications? Soft starter Variable frequency drive Both a and b None of the above HintThe soft starter is used in medium and low torque applications whereas the VFD used in high torque applications92). What are the advantages of a DOL starter? Easy to troubleshoot Easy to understand Most economical and cheap All of the above HintThe DOL starters are easy to troubleshoot, easy to understand, most economical, and cheap93). What are the advantages of disc motor? High-cost Smooth rotation with zero cogging Low-cost Both b and c HintThe advantages of disc motor are low cost and smooth rotation with zero cogging94). The disc motors are used in __________________ applications CD players VCR players Record players All of the above HintThe disc motors are used in CD players, VCR players, record players, etc95). The hysteresis motor is a type of ______________ motor Commutator motor Synchronous motor Induction motor Brushless DC motor HintThe hysteresis motor is a type of synchronous motor96). What is the standard form of SPM? Surface Permanent Magnet Surface Permanent Machine Solid Permanent Magnet None of the above HintThe standard form of SPM is Surface Permanent Magnet, it is a type of brushless DC motor97). What are the disadvantages of DOL starters? High starting current Mechanically harsh High starting torque All of the above HintThe DOL starter has a high starting current, high starting torque, and it is mechanically harsh98). The direct on-line starter is suitable for _____________ Conveyor belts Water pumps c Compressors All of the above HintThe direct on-line starter is suitable for conveyor belts, water pumps, and compressors99). What are the advantages of a star-delta starter? Good torque/ current performance Simple and rugged Cheap All of the above HintThe star-delta starter has good torque/current performance, and it is simple, cheap, and rugged100). What are the applications of variable frequency drive? Cane carrier drive Raw juice pumps Injection pumps All of the above HintThe variable frequency drive used in cane carrier drive, raw juice pumps, injection pumps, etc Time is Up! Time's up
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