ELECTRICAL MACHINES QUIZ

In a dc machine 4 pole lap winding is used. The number of parallel paths are?

2

4

1

8

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Which of the following is the largest conversion device?

Induction machine

Synchronous machine

DC machine

All of these

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A 3-phase, 50Hz, 4 pole induction motor is running at 1440 rpm and rotor input power is 2KW. Find the rotor output power?

2000W

1450W

1920W

1820W

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Which type motors are preferred for lathes?

Synchronous motor.

DC shunt motors.

Squirrel Cage induction motor.

Either A or B.

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In DC motors, under trailing pole tips, flux density will_______ ?

increase

decrease

None of these

either increase or decrease

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Torque angle of a synchorous machine operating from a constant voltage bus is usually defined as the space angle between

Stator mmf wave and resultant mmf wave.

Rotor mmf wave and stator mmf wave.

Rotor mmf wave and resultant flux density wave.

Stator mmf wave and resultant flux density.

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The speed regulation of a DC motor is given as

NnL/NfL.

(NnL − NfL)/NfL.

NnL − NfL.

(NfL − NnL)/NnL.

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A shunt generator is running at 1000 rpm. If flux is reduced by half, then what is the new speed?

0.

500.

2000.

1000.

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Slip exists in

induction motor.

none of above.

synchronous motor.

in both machines.

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If Pi and Pc represent core and full load copper loss respectively, the maximum KVA delivered to load corresponding to maximum efficiency is equal to rated KVA is

Pc/Pi

√(Pi/Pc)

(Pi/Pc)2

Pi/Pc

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