The number of slip rings on a squirrel cage induction motor is usually

Slip ring motor is preferred over squirrel cage induction motor where

A

High starting torque is required

B

Load torque is heavy

C

Heavy pull out torque is required

D

All of the above

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 the squirrel-cage induction motor the rotor slots are usually given slight skew

A

To reduce the magnetic hum and locking tendency of the rotor

B

To increase the tensile strength of the rotor bars

C

To ensure easy fabrication

D

None of the above

In squirrel cage induction motors, the rotor slots are usually given slight skew in order to

A

Reduce windage losses

B

Reduce eddy currents

C

Reduce accumulation of dirt and dust

D

Reduce magnetic hum

A double squirrel-cage induction motor has

A

Two rotors moving in opposite direction

B

Two parallel windings in stator

C

Two parallel windings in rotor

D

Two series windings in stator

The starting torque of a squirrel-cage induction motor is

A

low

B

negligible

C

same as full-load torque

D

slightly more than full-load torque

Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor?

A

By changing the number of stator poles

B

Rotor rheostat control

C

By operating two motors in cascade

D

By injecting e.m.f. in the rotor circuit

When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered

A

In series

B

In parallel

C

In series-parallel

D

In parallel with stator

A squirrel cage induction motor is not selected when

A

Initial cost is the main consideration

B

Maintenance cost is to be kept low

C

Higher starting torque is the main consideration

D

All above considerations are involved

The speed of a squirrel-cage induction motor can be controlled by all of the following except

A

Changing supply frequency

B

Changing number of poles

C

Changing winding resistance

D

Reducing supply voltage

The number of slip rings on a squirrel cage induction motor is usually

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