Electrical Machines Objective Questions – Set 11

The crawling in the induction motor is caused by

Which one of the following statement is correct ? In an induction motor if the air gap is increased then

Which of the following statements is/are correct?

Torque developed in the rotor is

In an induction motor, what is the ratio of rotor input to rotor copper loss?

Which of the following is the best way of starting for slip ring induction motor?

An induction motor when started on no load does not accelerate up to full speed but runs at 1/7th of the rated speed. The motor is said to be

The speed of stator rotating magnetic field with respect to rotor rotating magnetic field?

No load test on induction motor is conducted to find which of the following losses?

A 440 V, 3-phase, 10 pole and 50 HZ synchronous motor delivering a torque of 50 N-m, delivers a power of

An induction motor has a full load slip of 0.04. Its starting current is 5 times its full load current. what is the ratio of starting torque to the full load torque?

If we increase the rotor reactance value, the maximum torque will

When slip is greater than 1, then the motor is in which of the following region?

A smaller air gap in a induction motor helps to

A 3-phase, 50 Hz, 4 pole induction motor is running at 1440 rpm. Find the rotor efficiency?

The rotor power output of 3-phase induction motor is 15 KW. The rotor copper losses at a slip of 4% will be

Blocked rotor test is used to find which of the following losses ?

A 4 pole 50 Hz 1-phase induction motor is running at 1470 rpm. Find the forward and backward slips?

An induction motor is started using auto transformer and it has a full load slip(S_f) of 0.02. Its starting current(Ist) is 3 times its full load current(If). What is the ratio of starting torque(T_st) to full load torque(T_f)?

A starting torque of 40 Nm is developed in an induction motor by an auto transformer starter with a tapping of 30%. If the tapping of auto transformer is 60%, then what is the starting torque?

The supply voltage to an induction motor is reduced by 10%. By what percentage, approximately, will the maximum torque decrease?

An induction motor having 8 poles runs at 727.5 rpm. If the supply frequency is 50Hz, the emf in the rotor will have a frequency of

When applied rated voltage per phase is reduce to one half, the starting torque of three phase squirrel cage induction motor becomes

A 3-phase, 50 Hz, 4 pole induction motor is running at 1440 rpm and rotor input power is 2KW. Find the rotor copper loss?

Which of the following are the starting methods for squirrel cage induction motor?

The advantage of the double squirrel cage induction motor over single cage rotor is that its

In an induction motor, air gap power is 10 Kw and mechanically developed power is 8 Kw. What are the rotor ohmic losses?

A 3-phase, 50Hz, 4 pole induction motor is running at 1440 rpm and rotor input power is 2KW. Find the rotor output power?

From no load to full load the slip will

In induction generator the slip is always