Electrical Machine MCQs
36. Question
A 200 V DC series motor, when operating from rated voltage while driving a certain load, draws 10 A current and runs at 1000 rpm. The total series resistance is 1 . The magnetic circuit is assumed to be linear. At the same supply voltage, the load torque is increased by 44%. The speed of the motor in rpm (rounded to the nearest integer) is
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37. Question
A three-phase, 900 kVA, 3kV/√3kV ( /Y, ) 50 Hz transformer has primary (high voltage side) resistance per phase of 0.3 and secondary (low voltage side) resistance per phase of 0.02 . Iron loss of the transformer is 10 kW. The full load % efficiency of the transformer operated at unity power factor is _________ (upto 2 decimal places).
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38. Question
A separately excited dc motor has an armature resistance 0.05 . Ra = The field excitation is kept constant. At an armature voltage of 100 V, the motor produces a torque of 500 Nm at zero speed. Neglecting all mechanical losses, the no-load speed of the motor (in radian/s) for an armature voltage of 150 V is _________ (upto 2 decimal places).
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39. Question
The graph of a network has 8 nodes and 5 independent loops. The number of branches of the graph is
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40. Question
In a salient pole synchronous motor, the developed reluctance torque attains the maximum value when the load angle in electrical degree is
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