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Under short circuit condition the power factor of synchronous machine is:

Under short circuit condition the power factor of synchronous machine is: Correct Answer almost zero lagging

Concept:

Under short circuit condition

V = 0, and Ia = ISC

emf equation for alternator:

E = V + Ia Zs

V = terminal voltage

Ia = armature current

ZS = synchronous reactance

Calculation:

Under short circuit condition

V = 0, and Ia = ISC

So E = Ia ZS = Ia XS

Now the field current required under SC condition is to generate a voltage to compensate the drop due to synchronous impedance mainly drop due to armature reaction.

Under short circuit condition, the effect of armature reaction is purely demagnetizing and power factor become Zero lagging.

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