Electrical Machines
What will be the e.m.f. generated by a 4 pole lap connected DC Generator rotating at 1500 r.p.m.? Its flux per pole is 0.4 mWb and total no of armature conductors is 1000.

 20 volts.
 10 volts.
 40 volts.
 30 volts.

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Electrical Machines
Ward-Leonard system for controlling the speed of a DC motor is used where

 The speed in both the direction is required.
 The accuracy in speed control is required.
 Very fine speed control over the whole range from zero to normal speed is required.
 All of above.

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Electrical Machines
In dc machines, the field system has to be provided on stator unlike synchronous machines Where in it could be on any member, because

 it gives more uniform air-gap flux distribution
 commutator action is not possible otherwise
 dc machines are comparatively low rating machines.
 it reduces field structure iron losses

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