Electrical Machines
A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net voltage across the armature resistance at the time of plugging will be

 6 V
 240 V
 474 V
 234 V

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Electrical Machines
Short circuit test is performed on a transformer with a certain impressed voltage at rated frequency. If the short circuit test is now performed with the same magnitude of impressed voltage, but at frequency higher than the rated frequency then

 The magnetude of current will increase, but power factor will decrease.
 The magnitude of current will decrease but the power factor will increase.
 The magnitude will both increase.
 The magnitude of circuit as well as the power factor will decrease.

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Electrical Machines
The synchronous reactance( Xs) is the

 reactance due to armature reaction of the machine
 combined reactance due to armature reaction and leakage flux
 reactance due to leakage flux
 reactance either due to armature reaction or leakage flux

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