ELECTRICAL MACHINES QUIZ

Generators work on the principle of production of

dynamically and statically induced emf.

dynamically induced emf.

statically induced emf.

None of these

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In DC series motor the speed is ______________ proportional to the armature current.

has no relation.

inversely.

directly.

none of these.

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In a DC Shunt Motor if the load current increases keeping the terminal voltage constant, then flux will

increase.

decrease.

any of the above.

remain constant.

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In case of a compensated DC series motor, the compensating winding is provided

In parallel with the field winding.

In series with the armature winding.

As a separate unit.

In parallel with the armature winding.

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In a DC machine, which of these parameters remain the same whether it runs as a DC motor or a DC generator?

Armature current.

Can not be determined.

Mechanical power.

Induced emf.

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Number of slip rings in 3-phase synchronous motor will be

1

0

3 or 4

2

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With the increase in speed of DC motor

Both back emf as well as line current fall.

Back emf increase but line current falls.

Both back emf as well as line current increase.

Back emf falls and line current increase.

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In dc machine armature windings are placed on rotor because of the necessity for

electromechanical energy conversion.

commutation.

generation of voltage.

development of torque.

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In DC machines internal characteristics are plotted between

Eg vs load current

Vt vs load current

Eg vs Ia

Vt vs Ia

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At slip s = 1 torque developed in machine is

none.

electromagnetic torque.

starting torque.

maximum torque.

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