A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The external resistance to be added in the armature circuit to limit the armature current to 125% of its rated value is

Electrical Machines
A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The external resistance to be added in the armature circuit to limit the armature current to 125% of its rated value is

31.1 Ω

15.1 Ω

31.9 Ω

15.9 Ω

31.1 Ω

15.1 Ω

31.9 Ω

15.9 Ω

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Electrical Machines
Example of double excited machine is

Both are correct.

Synchronous motor.

DC Shunt Motor

None of these

Both are correct.

Synchronous motor.

DC Shunt Motor

None of these

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Electrical Machines
The functions of inter poles are

None of these

nullify reactance voltage and improve the commutation.

reduce cross magnetization effect and improve commutation

both 1 and 2

None of these

nullify reactance voltage and improve the commutation.

reduce cross magnetization effect and improve commutation

both 1 and 2

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Electrical Machines
The armature mmf of a DC machine has

trapezoidal space distribution and is stationary in space.

stepped distribution and rotates at the speed of armature.

triangular space distribution and rotates at the speed of armature.

triangular space distribution and is stationary in space.

trapezoidal space distribution and is stationary in space.

stepped distribution and rotates at the speed of armature.

triangular space distribution and rotates at the speed of armature.

triangular space distribution and is stationary in space.

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Electrical Machines
If the temperature of armature resistance is increased, the speed of a series motor would

not change.

increase.

decrease.

None of above.

not change.

increase.

decrease.

None of above.

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Electrical Machines
A short-shunt cumulatively-compounded dc generator builds up a voltage of 220 V at no load at rated speed. If it is operated as a differentially compounded generator, other things remaining the same, it would build up

more than 220 V

6 V

220 V

somewhat less than 220 V

more than 220 V

6 V

220 V

somewhat less than 220 V

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Electrical Machines

Electrical Machines Example of double excited machine is

Electrical Machines The functions of inter poles are

Electrical Machines The armature mmf of a DC machine has

Electrical Machines If the temperature of armature resistance is increased, the speed of a series motor would

Electrical Machines A short-shunt cumulatively-compounded dc generator builds up a voltage of 220 V at no load at rated speed. If it is operated as a differentially compounded generator, other things remaining the same, it would build up

Electrical Machines
Example of double excited machine is

Electrical Machines
The functions of inter poles are

Electrical Machines
The armature mmf of a DC machine has

Electrical Machines
If the temperature of armature resistance is increased, the speed of a series motor would

Electrical Machines
A short-shunt cumulatively-compounded dc generator builds up a voltage of 220 V at no load at rated speed. If it is operated as a differentially compounded generator, other things remaining the same, it would build up