A hydraulic turbine having rated speed of $$250$$ $$rpm$$ is connected to a synchronous generator. In order to produce power at $$50$$ $$Hz,$$ the number of poles required in the generator are

A $$4$$-pole, $$3$$-phase, double layer winding is housed in a $$36$$-slot stator for an $$ac$$ machine with $$60$$ degree phase spread. Coil span is $$7$$ slot pitches. Number of slots in which top and bottom layers belong to different phases is.

The flux per pole in a synchronous motor with the field circuit ON and the stator disconnected from the supply is found to be $$25$$ $$mWb.$$ When the stator is connected to the rated supply with the field excitation unchanged, the flux per pole in the achine is found to be $$20$$ $$mWb$$ while the motor is running on no load. Assuming no load losses to be zero, the no load current down by the motor from the supply

A star-connected 440 V, 50 Hz alternators has per phase synchronous reactance of 10 Ω. It supplies a balanced capacitive load current of 20 A, as shown in the per phase equivalent circuit of Figure. It is desirable to have zero voltage regulation. The load power factor should be