The power scale of circle diagram of an induction motor can be found from

In the circle diagram for induction motor, the diameter of the circle represents

A

Slip

B

Rotor current

C

Running torque

D

Line voltage

The complete circle diagram of induction motor can be drawn with the help of data found from

A

No-load test

B

Blocked rotor test

C

Stator resistance test

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

A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will

A

remain same

B

go down

C

improve

D

none of the above

Which is of the following data is required to draw the circle diagram for an induction motor?

A

Block rotor test only

B

No load test only

C

Block rotor test and no-load test

D

Block rotor test, no-load test and stator resistance test

The circle diagram for an induction motor cannot be used to determine

A

Efficiency

B

Power factor

C

Frequency

D

Output

A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because

A

synchronous motor has no slip

B

stator supply is not required to produce magnetic field

C

mechanical load on the rotor remains constant

D

synchronous motor has large airgap

The power factor of a synchronous motor is better than that of induction motor because

A

stator supply is relieved of responsibility of producing magnetic field

B

mechanical load on the motor can be adjusted

C

synchronous motor runs at synchronous speed

D

synchronous motor has large air gap

The complete circle diagram of induetion motor can be drawn with the help of data found from

A

noload test

B

blocked rotor test

C

stator resistance test

D

all of the above

The radius of circle A is r, and the radius of circle B is 3/4r. What is the ratio of the area of circle A to the area of circle B?

A

16 to 9

B

9 to 16

C

1 to 4

D

4 to 3

The power scale of circle diagram of an induction motor can be found from

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