# Electrical Engineering Questions And Answers :: Polyphase Induction Motors: part3

Electrical Engineering : Polyphase Induction Motors QUESTIONS AND ANSWERS :: part3 : 1 to 5

Following Electrical Engineering Multiple choice objective type questions and answers will help you in BSNL JTO, GATE 2021 and IES 2021 examinations :

 1.In case of 3-phase induction motors, plugging means pulling the motor directly on line without a starter locking of rotor due to harmonics starting the motor on load which is more than the rated load interchanging two supply phases for quick stopping ANSWER : : interchanging two supply phases for quick stopping Explanation :
 2.In a three-phase induction motor power factor at starting is high as compared to that while running power factor at starting is low as compared to that while running power factor at starting in the same as that while running power factor at starting is low as compared to that while running ANSWER : The vafcie of transformation ratio of an induction motor can be found by Explanation :
 3.Blocked rotor test on induction motors is used to find out leakage reactance power factor on short circuit short-circuit current under rated voltage all of the above ANSWER : : all of the above Explanation :
 4.A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles. The slip of the machine will be 0.01 0.02 0.03 0.04 ANSWER : : 0.04 Explanation :
 5.The torque of a rotor in an induction motor under running condition is maximum at the unit value of slip at the zero value of slip at the value of the slip which makes rotor reactance per phase equal to the resistance per phase at the value of the slip which makes the rotor reactance half of the rotor ANSWER : : at the value of the slip which makes rotor reactance per phase equal to the resistance per phase Explanation :

More Polyphase Induction Motors QUESTIONS AND ANSWERS available in next pages

Health is the greatest gift, contentment is the greatest wealth -Buddha
If your ship doesnât come in, swim out to meet it!-Jonathan Winters