Insertion of resistance in the stator of an induction motor

The power input to an induction motor is 50 kW when it is running at 4% slip. If the stator resistance and core losses are neglected, the rotor copper loss is

A

30 kW

B

20 kW

C

2 kW

D

4 kW

Insertion of resistance in the rotor of an induction motor to develop a given torque

A

Decreases the rotor current

B

Increases the rotor current

C

Rotor current becomes zero

D

Rotor current remains same

Insertion of resistance in the rotcir of an induction motor to develop a given torque

A

decreases the rotor current

B

increases the rotor current

C

rotor current becomes zero

D

rotor current rernains same

A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is

A

Slop speed operation

B

High starting torque

C

Low windage losses

D

All of the above

In an induction motor the relationship between stator slots and rotor slots is that

A

Stator slots are equal to rotor slots

B

Stator slots are exact multiple of rotor slots

C

Stator slots are not exact multiple of rotor slots

D

None of the above

What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero?

A

The slip of the motor will be 5%

B

The rotor will not run

C

The rotor will run at very high speed

D

The torque produced will be very large

Temperature of the stator winding of a three phase induction motor is obtained by

A

Resistance rise method

B

Thermometer method

C

Embedded temperature method

D

All above methods

A 4 pole 50 Hz induction motor is running at 1300 rpm. Find the speed of stator magnetic field with respect to the rotor?

A

200 rpm

B

1500 rpm

C

1300 rpm

D

1700 rpm

While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by

A

induction motor torque in field winding

B

induction motor torque in damper winding

C

eddy current and hysteresis torque in pole faces

D

reHetance motor torque due to saliency of the rotor

E

all of the above methods

While starting a synchronous motor by induction motor action, field winding is usually

A

connected to D.C. supply

B

short-circuited by low resistance

C

kept open-circuited

D

none of the above

Insertion of resistance in the stator of an induction motor

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