Electrical Machines
A large series motor is never started without some mechanical load on it because otherwise it will

 draw too much current.
 develop excessive speed and damage itself.
 produce sparking at brushes.
 open fuse or circuit breaker.

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Electrical Machines
The mmf produced by rotor currents of a 3 - Φ induction motor

  is at standstill with respect to stator mmf.
  rotates at slip speed with respect to stator mmf.
  rotates at synchronous speed with respect to rotor.
  rotates at the speed of rotor in the air gap.

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Electrical Machines
A DC shunt generator builds up to a voltage of 220 V at no load while running at its rated speed. If the speed of the generator is raised by 25% kepping the circuit conditions unaltered, then the Voltage to which the machine would build up will

 increase to a value greater than 1.25 times 220 V
 not change and remain at 220 V
 increase to 1.25 times 220 V
 increase to value lying between 220 V and 1.25 times 220 V

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