Answer / siva

The Goerges phenomenon is the operation of a 3-phase wound-
rotor induction motor at half of synchronous speedand it is
obtained by unbalancing the rotor circuit. If the motor is
started with one rotor phase opened or with rotor
impedances greatly unbalanced, it will accelerate to half
speed and operate stably as a motor or generator.The motor
may be operated stably at half or full speed. The torque at
half speed is greater than at full speed, and may be almost
as great as the rated torque for a balanced rotor. It may
be desirable to operate an induction motor at half speed
intermittently or as a temporary measure. Disadvantages of
half speed operation are the low power factor, low pull-out
torque, the subfrequency line currents, and motor
vibrations.

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