In a three-phase induction motor, the number of poles in the rotor winding is always

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

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

When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor

A

remains same as the original value

B

decreases to half the original value

C

tends to becomes zero

D

increases to two times the original value

In which single-phase motor, the rotor has no teeth or winding ?

A

Split phase motor

B

Reluctance motor

C

Hysteresis motor

D

Universal motor

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

After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on

A

running winding

B

rotor winding

C

field winding

D

compensating winding

If starting winding of a single-phase induction motor is left in the circuit, it will

A

run faster

B

spark at light loads

C

draw excessive current and overheat

D

run slower

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

The torque of a rotor in an induction motor under running condition is maximum

A

At the unit value of slip

B

At the zero value of slip

C

At the value of the slip which makes rotor reactance per phase equal to the resistance per phase

D

At the value of the slip which makes the rotor reactance half of the rotor

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

In a three-phase induction motor, the number of poles in the rotor winding is always

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