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 2024 and IES 2024 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

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

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

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

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

More Polyphase Induction Motors QUESTIONS AND ANSWERS available in next pages

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