ELECTRICAL MACHINES QUIZ

The current drawn by a 220 V DC series motor of armature resistance 0.5 Ω and back emf of 200 V is

440 A.

400 A.

44 A.

40 A.

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YOUR ANSWER : ?

What does the use the of height flux density value in transformer design lead to?

Increase in weight/KVA.

Decrease in weight/KVA.

Reduced iron loss.

Reduced copper loss.

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A 3 - ÃŽÂ¦ slip ring motor has

short-circuited rotor.

any of the above.

double cage rotor.

wound rotor.

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Under operating conditions the rotor conductor should be _________________ in induction motor.

always closed.

always opened.

none.

semi closed or semi opened.

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Slip speed is the

sum of synchronous and rotor speeds.

difference of actual rotor speed and synchronous speed.

difference of synchronous speed and actual rotor speed.

half of the sum of synchronous and rotor speeds.

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A voltmeter gives 120 oscillations per minute when connected to the rotor of an induction motor. The frequency is 50Hz. The slip of the motor is

2%

4%

25%

5%

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In an induction motor, air gap power is 10 Kw and mechanically developed power is 8 Kw. What are the rotor ohmic losses?

2KW

3KW

0.5Kw

1.5KW

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The squirrel cage induction motors are provided with blades in order to

none of these.

balance the rotor dynamically.

facilitate cooling of rotor.

eliminate noise.

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Armature reaction of an unsaturated DC machine is

none of above.

crossmagnetising.

demagnetising.

magnetising.

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Which of the DC Motor use flywheel?

Series motor.

Shunt motor.

Differently compared motor.

Cumulatively compound motor.

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