__________ method of starting a three phase induction motor needs six terminals.

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

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

The starting torque of a three phase induction motor can be increased by

A

Increasing slip

B

Increasing current

C

Both (A) and (B)

D

None 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

In _________ method of staging three phase induction motors the starting voltage is not reduced.

A

Autotransformer

B

Star-delta

C

Slip ring

D

Any of the above

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

Torque developed by a single phase induction motor at starting is

A

pulsating

B

uniform

C

none of the above

D

nil

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 case one phase of a three-phase synchronous motor is short-circuited the motor will

A

Not start

B

Run at $$\frac{2}{3}$$ of synchronous speed

C

Run with excessive vibrations

D

Take less than the rated load

In a three-phase induction motor

A

Power factor at starting is high as compared to that while running

B

Power factor at starting is low as compared to that while running

C

Power factor at starting in the same as that while running

D

None of these

__________ method of starting a three phase induction motor needs six terminals.

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