ELECTRICAL MACHINES QUIZ

A load of 900 lbs is to be raised with a lift car weighting 855 lbs at a speed of 110 feet per minute, the over balance being 40 % and percentage efficiency 45 %. Find the horse power of the motor without counterweight

150.

160.

170.

180.

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Two dc machines A and B, using the same conductor material, have armature circuit resistances of 0.4 Ω and 1.2 Ω respectively. Of the two machines,

B is bigger than A for the same current rating

A is bigger than B for the same current rating

A is bigger than B for the same voltage rating

both are of the same size for the same current rating

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A dc shunt generator, when commissioned after a major repair of the field system, failed to build Up voltage. It was because

field resistance was higher than critical resistance

field system lost residual magnetism

there was a break in the armature circuit

field winding was wrongly connected

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A DC series motor has which of the following characteristics?

Can be started easily without load.

Has a poor torque.

Has a almost constant speed.

Has its field winding consinting of thick wire and less no of turns.

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Eb/Vt ratio of a DC motor is an indication of

efficiency.

running torque.

starting torque.

speed regulation.

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We can apply source transformation to voltage source when a resistance is connected to it in

13 HP.

10 HP.

14 HP.

15 HP.

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In above question, the output power delivered by generator G1 and G2 will be

9.6 kW, 12 kW.

5.7 kW, 8.7 kW.

9.3 kW, 9.3 kW.

6.3 kW, 9.3 kW.

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The leakage reactance of a 3-phase alternator is determined by performing

open circuit and zero power factor tests.

zero power factor and slip tests.

short circuit and slip tests.

open circuit and short circuit tests.

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Which type motors are preferred for lathes?

DC shunt motors.

Either A or B.

Squirrel Cage induction motor.

Synchronous motor.

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An electric motor with constant output power will have a torque speed characteristics in the form of a

Circle about the origin.

Straight line through the origin.

Rectangular hyperbola

Straight line parallel to the speed axis.

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