DC MOTORS QUIZ

If any two phases for an induction motor are interchanged

The motor will burn

The motor will run in reverse direction

The motor will run at reduced speed

The motor will not run

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The condition of induction motor at stand still resemble those of a transformer whose secondady is _______

None of the listed here

Short circuited

Open circuited

Supplying a variable resistive load

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A 3 phase 440 v, 50 Hz induction motor has 4% slip. The frequency of rotor emf will be

20 Hz

2 Hz

50 Hz

200 Hz

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The shaft of induction motor is made of

Stiff

Any of the listed here

Flexible

Hollow

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5 H.P., 50Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest?

1440 rpm

1000 rpm

2880 rpm

730 rpm

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The good power factor of an induction motor can be achieved if the average flux density in the air gap is

Infinity

Absent

Large

Small

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The complete circle diagram of induction motor can be drawn with the help of data found from

No-load test

Blocked rotor test

Stator resistance test

All of these

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The reactance of the rotor circuit of a 3-phase induction motor is maximum at

Half full load

Full load

No load

Starting

TRUE ANSWER : ?
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The injected e.m.f. in the rotor of induction motor must have

The same frequency as the slip frequency

High value for the satisfactory speed control

The same phase as the rotor e.m.f.

Zero frequency

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In an induction motor, the ratio of rotor cu loss and rotor input is given by

S

1/S

S/1-S

1-S

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