Poly Phase Induction Motor Question & Answers September 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 Hint Read more about AC Motor 2). How many parts does the three-phase induction motor consist of? One Two Three Four Hint Read more about Three Phase Induction Motor 3). What are the main parts of the stator? Stator winding Stator core Outer frame All of the above Hint 4). The cost of the wound motor is ____________ Less Very less More Very expensive Hint 5). The size of the wound motor is ____________ Small Very small Large Very large Hint 6). What is the standard form of RMF? Rotating Magnetic Field Rotor Magnetic Field Rotating or Rotor Magnetic field None of the above Hint 7). What is the standard form of LIM? Linear Induction Motor Non-linear Induction Motor Line Induction Motor None of the above Hint 8). The induction motor frame is made up of ___________ Cast iron Silicon Aluminum None of the above Hint 9). The induction motor shaft is made of _________ Silver Copper Carbon steel None of the above Hint 10). The slip is around _____________ in medium size induction motors <l% 2% 3% 4% Hint 11). Which one of the materials is used to made slip rings? Copper Phospor bronze Silver None of the above Hint 12). ___________ are the types of poly-phase induction motor Single-phase Universal Wound rotor & squirrel cage All of the above Hint 13). 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 Hint 14). The ratio of synchronous speed divided by a rotor speed is known as ___________ speed Slip Shaft Synchronous None of the above Hint 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)/P None of the above Hint 16). 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 Hint 17). The induced torque is defined as a ratio of ____________ Power/speed Speed/power Voltage/Current None of the above Hint 18). The induction motor rotor runs at _____________ speed Synchronous Asynchronous Below synchronous None of the above Hint 19). The induction motor torque is _____________ proportional to the slip Directly Inversely Either directly or inversely None of the above Hint 20). The percentage slip in an induction motor depends on ___________ in motor Frequency Voltage Copper losses None of the above Hint 21). If the air gap is increased in an induction motor, the power factor will be ____________ Very high High Low None of the above Hint 22). 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 Hint 23). What are the advantages of LIM motors? Simple Gives higher speed More efficient All of the above Hint 24). The starting torque is high in ____________ induction motor Squirrel cage Slip ring Both a and b None of the above Hint 25). The speed control by rotor resistance is possible in ___________ induction motor Squirrel cage Slip ring Both a and b None of the above Hint Polyphase Induction Motor MCQs for Exams 26). Which one of the following is a type of stator? Autotransformer, star-delta Rotor resistance Direct on-line, stator resistance All of the above Hint 27). What are the advantages of stator? Cheap Simple in construction Both a and b None of the above Hint 28). Which one of the following stator costs is more? Autotransformer Star delta Direct on line All of the above Hint 29). Which one of the following stators doesn’t decrease the starting current? Autotransformer Star delta Direct on line All of the above Hint 30). The direct on-line stator is used up to _____________ HP One Two Four Five Hint 31). Which one of the following stators used above 20 HP? Autotransformer Star delta Direct on line All of the above Hint 32). Which one of the following stators is very cheap? Autotransformer Star delta Direct on line All of the above Hint 33). What are the advantages of auto-transformer? High-efficiency Copper losses are less VA rating is more All of the above Hint 34). Which one of the following transformers is can’t be used as variac? Two winding Single Both a and b None of the above Hint 35). Which one of the following transformers has more KVA rating? Two winding Auto winding Both a and b None of the above Hint 36). Which one of the following costs is slightly higher? Squirrel cage Slip ring Both a and b None of the above Hint 37). The leakage and resistance values are more in _____________ transformer Two winding Auto winding Both a and b None of the above Hint 38). How many windings do the two winding transformers have? One Two Three Four Hint 39). The wound or slip ring rotor is used for ______________ Elevators Cranes Lifts All of the above Hint 40). The squirrel cage rotor is used for ______________ Water pumps lathes Fans All of the above Hint 41). The speed control by rotor resistance is not possible in ______________ rotor Wound Squirrel cage Both a and b None of the above Hint 42). In squirrel cage rotor, the rotor copper losses are _____________ Less More Very less None of the above Hint 43). The difference between rotor speed and synchronous speed of RMF is known as ______________ Synchronous speed Slip speed Rotor speed None of the above Hint 44). Which one of the following system costs is high? Brushless DC motor Brushed DC motor Induction motor All of the above Hint 45). In which one of the following motors the controller is required? Brushless DC motor Brushed DC motor Induction motor All of the above Hint 46). In which one of the following motors the speed range is low? Brushless DC motor Brushed DC motor Induction motor All of the above Hint 47). Which one of the following has less starting current? Squirrel cage Slip ring Both a and b None of the above Hint 48). How many windings does auto-transformer have? One Two Three Four Hint 49). The copper losses are more in ___________ transformer Two winding Auto winding Both a and b None of the above Hint 50). The size and cost is high in _______________ transformer Two winding Auto winding Both a and b None of the above Hint Polyphase Induction Motor Important MCQs 51). Which one of the following transformers has less efficiency? Two winding Auto winding Both a and b None of the above Hint 52). In which one the following motor the special starting circuit is required? Brushless DC motor Brushed DC motor Induction motor All of the above Hint 53). The motor control is categorized into _____________types based on the functions served Motor protection Speed control Torque control All of the above Hint 54). What is the standard form of BLDC? Brushed DC Motor Brush DC Motor Brushless DC Motor None of the above Hint 55). What is the standard form of CPAP? Continuous Positive Airway Pressure Continuous Pressure Airway Positive Continuous Pressure Airway Pressure None of the above Hint 56). 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 Hint 57). 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 Hint 58). Which one of the following motors has a fast dynamic response? VR motor PM motor Both a and b None of the above Hint 59). Which one of the following motors doesn’t have detent torque? VR motor PM motor Both a and b None of the above Hint 60). Which one of the following motors has a high maximum stepping rate? PM motor VR motor Both a and None of the above Hint 61). Which one of the following motors has a high step angle? VR motor PM motor Both a and b None of the above Hint 62). _________________ 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 Hint 63). The low inertia DC motors are categorized into _______________ One Two Three Four Hint 64). Which one of the following is denoted by CX? Control transmitter Control receiver Control transformer Control differential Hint 65). Which one of the following is denoted by CD? Control transmitter Control receiver Control transformer Control differential Hint 66). The synchros are used in servomechanism for _____________ Error detection Torque transmission Subtracting and adding rotary angles All of the above Hint 67). What is the standard form of SR motor? Switched Reluctance Simple Reluctance Switched Resistance None of the above Hint 68). The switched reluctance motor has power rating up to _____________ 10KW 40KW 20KW 75KW Hint 69). The variable reluctance motor has ______________ Low power rating Lower efficiency Both a and b None of the above Hint 70). What is the standard form of PMBL? Permanent Magnet Brushed Machines Permanent Magnet Brush Less Machines Permanent Magnet Machines None of the above Hint 71). Which one of the following is a type of AC motor? Commutator motor Synchronous motor Induction motor All of the above Hint 72). The stepping motor is categorized into _________________ One Two Three Four Hint 73). Which one of the following motors is not a type of induction motor? Eddy current Single phase Wound rotor type Reluctance motor Hint 74). The winding field DC motors are categorized into _______________ One Two Three Four Hint 75). The surface permanent magnet type motor is a _______________ motor Commutator motor Synchronous motor Induction motor Brushless DC motor Hint Polyphase Induction Motor MCQs with Hints 76). Which one of the following is denoted by CR? Control transmitter Control receiver Control transformer Control differential Hint 77). Which one of the following motors is not a self-starting motor? Synchronous motor Induction motor Both a and b None of the above Hint 78). The embedded magnet rotor is used in _______________ Fans Pumps Irrigation All of the above Hint 79). What are the components of the motor? Rotor, bearing Stator, bracket or endplate Lead wire All of the above Hint 80). ___________________ are the type of motors classified by the principle of conversion Electromagnetic motor Ultrasonic motor Both a and b None of the above Hint 81). ______________ 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 Hint 82). Which one of the following is denoted by CT? Control transmitter Control receiver Control transformer Control differential Hint 83). ______________ 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 Hint 84). The variable frequency drive has ________________ sections Converter Inverter DC bus All of the above Hint 85). The variable frequency drives are used for ____________ the motor Start Control Stop All of the above Hint 86). Which one of the following has fewer energy savings? Soft starter Variable frequency drive Both a and b None of the above Hint 87). ___________________ 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 Hint 88). _____________ are the type of PM DC motors by armature type Slotted type Coreless type Slotless type All of the above Hint 89). What is the standard form of IPM? Inferior Permanent Magnet Interior Permanent Magnet Insulated Permanent Magnet None of the above Hint 90). The space requirement is more in _________________ Soft starter Variable frequency drive Both a and b None of the above Hint 91). 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 Hint 92). What are the advantages of a DOL starter? Easy to troubleshoot Easy to understand Most economical and cheap All of the above Hint 93). What are the advantages of disc motor? High-cost Smooth rotation with zero cogging Low-cost Both b and c Hint 94). The disc motors are used in __________________ applications CD players VCR players Record players All of the above Hint 95). The hysteresis motor is a type of ______________ motor Commutator motor Synchronous motor Induction motor Brushless DC motor Hint 96). What is the standard form of SPM? Surface Permanent Magnet Surface Permanent Machine Solid Permanent Magnet None of the above Hint 97). What are the disadvantages of DOL starters? High starting current Mechanically harsh High starting torque All of the above Hint 98). The direct on-line starter is suitable for _____________ Conveyor belts Water pumps c Compressors All of the above Hint 99). What are the advantages of a star-delta starter? Good torque/ current performance Simple and rugged Cheap All of the above Hint 100). What are the applications of variable frequency drive? Cane carrier drive Raw juice pumps Injection pumps All of the above Hint Time is Up! Time's up
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