Virtual lab

No-Load Test

1) Consider the following statement: As a 3 phase induction motor is loaded from no load to rated load 1)There is an improvement in the power factor 2)The torque increases almost linearly with respect to slip 3)The air gap flux falls sharply

1, 2 and 3 are correct

1 and 2 are correct

2 and 3 are correct

1 and 3 are correct

2) At a slip of 4%, the maximum possible speed of a 3 phase squirrel cage induction motor is:

2880 rpm

3000 rpm

1500 rpm

1440 rpm

3) By increasing resistance in the rotor circuit of a slip ring induction motor,

both the starting current and torque reduce

both the starting current and torque increase

the starting current increases and torque decreases

the starting current decrease and torque increase

4) A 5% change in the supply frequency will increase the synchronous speed of the induction motor by

-5%

10%

-10%

5) The emf induced in the rotor of a 3 phase induction motor is proportional to the:

Relative speed between stator field and rotor conductors

Speed of the stator field

Speed of the rotor

1-slip

Shakshat Virtual Lab

INDIAN INSTITUTE OF TECHNOLOGY GUWAHATI