Dears, If we have a 3phase synchro 1

[ele.engineer]

Dears,
If we have a 3phase synchronous generator, mechanically connected to gas turbine. and both the generator and the turbine are off, and by fault the circuit breaker become closed , is the the generator shaft will rotate??
Note : for normal operation after starting the turbine the generator shaft start to rotate and there is a PMG in the generator ,the o/p of the PMG is connnected to AVR and this AVR supply the the exciter stator and the o/p voltage for the exciter supply the main field for generator.
Thanks

 

[ScottyUK]

It depends on the design of the rotor but most will develop sufficient torque to rotate the turbine, particularly if the bearing lift oil is available to reduce the breakaway friction between shaft and bearing. It is improbable that the torque will be sufficient to rotate the shaft anywhere near normal running speed, so it will run at a high slip and damage the rotor if allowed to persist. Most modern protection relays have the ability to detect a closure onto a dead machine.

 

[ele.engineer]

The rotor is salient pole type , 4pole.

 

[GroovyGuy]

Howdy Mohamed,
I am quite sure that the motor will start to accelerate once the CB is closed, but only if the motor has to be equipped with a squirrel-cage starting winding. Most synch motors are started this way. I trust that your CB is protected against unintended closure.
GG

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