Synchronizing Generators

Fo Synchronisation, there should be two source of Power. Normally we call, Running source & Incoming source. This can be from Genertor terminal or from Grid.

Criteria for Syncronisation :

1 Voltages of both the source should be same or withing set limits of synchronising relay.

2. Frequency of both the source should be same or within set limit.

3. All the phases must be in line with corsponding phases of another source.

4. Phase Sequence of bot hte soures should be same.

For varification of this we need, synchroscope, check synchronising relay, guard realsy, indication lamps etc.

Synchroscope & check syncro relays are connected to PT sec of each source. When 1 to 3 above conditions will be satisfied, Syncroscope will be at 10Oclock position & relay will make contact, which is used in closing circuit of circuit breaker of Incoming source.

If frequency of both the sources are not same then syncroscope rotates. Its speed depends on the difference. If freq of Incoming source is higher then the running then scope will rotate in clockwise direction otherwise reveres. Angle of the scope depends on the phase angle difference between both the source.

While closing the circuit breaker, we must take care that phase angle of both the source must be same, means, scope must be on 12 oclock position. & Rotation must be in clock wise, means freq of incoming source must be more then the running. So that on closing of circuit breaker Generator (If it is incoming source) will start generating Power, else there will be reverese flow of Power.

Guard relay ensures that, closing comand must come after check synchonising relay gives comand. We can not keep closing switch of circuit breaker "ON" & wait for check synchro relay to give comand. Fisrt relay must give comand & then we should give close comand to breaker.

Speed of the synchroscope should be slow (how much slow that we come to know only after opearting experience) & clock wise direction. Reason is there should not be major power fluctuation on sources imediatly on closing the breaker. Load on each source must be gradually increased or decreased.

I hope I expleained more then enough.

For drawings, I am sorry, I dont know how to attach any file here.

Ajay