GATE EE 2007 | Synchronous Machines Question 27 | Electrical Machines

GATE EE 2007

MCQ (Single Correct Answer)

-0.3

A three phase synchronous motor connected to ac mains is running at full load and unity power factor. If its shaft load is reduced by half, with field current held constant, its new power factor will be

unity

leading

lagging

dependent on machine parameters

GATE EE 2006

MCQ (Single Correct Answer)

-0.3

A synchronous generator is feeding a zero power factor (lagging) load at rated current the armature reaction is

magnetizing

demagnetizing

cross magnetizing

Ineffective

GATE EE 2005

MCQ (Single Correct Answer)

-0.3

In relation to the synchronous machines, which one of the following statements is false?

In salient pole machines, the direct-axis synchronous reactance is greater than the quadrature-axis synchronous reactance

The damper bars help the synchronous motor self-start

Short circuit ratio is the ratio of the field current required to produce the rated voltage on open circuit to the rated armature current

The V-curve of a synchronous motor represents the variation in the armature current with field excitation, at a given output power

GATE EE 2004

MCQ (Single Correct Answer)

-0.3

For a given stepper motor, the following torque has the highest numerical value.

Detent torque

Pull-in torque

Pull-out torque

Holding torque

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