when we trying to manual synchronizing with grid, after synchronizing the grid and sf 6 breakers opened. this will happened two times then the second time no problem comes that means grid not opened. but the auto synchronizing there is no problem. so please reply your post if anybody have the answers for this problem.

 

jj,

Usually when this happens during manual synchronization it's because the voltage matching isn't done correctly resulting in excessive reactive current (usually leading) at some point in the system.

To understand why a particular breaker is opening you need to look at the breaker trip (open) circuit drawing for that breaker and physically look at all the relays and trip interlocks when the unexpected trip occurs so that you can determine what condition is causing the breaker to be tripped (opened).

It would also be very surprising to learn that the protective relay that tripped (opened) the breaker did not also cause an alarm to be annunciated somewhere in the plant or the switch yard where the breaker is located. Please also have a look at all the alarm logs and any SOE (Sequence of Event) recorder in the plant or switch yard to determine the cause of the breaker tripping (opening).

Again, voltage matching is usually NOT part of the synch permissive circuit during manual synchronization and something related to a voltage/reactive current mismatch is likely the cause of the breaker opening.

Please write back to let us know what you discover.

 

JJ,

I experienced this problem couple months ago. The breaker tripped with no indication on the relay protection. The breaker tripped just after synchronization. We tried Twice or three times every time we want to sync the gen and then we succeeded. But this was not the condition we desired.

During troubleshoot I disassembled the breaker and I found the mechanical locking of the breaker is wearing. After I fix the problem, adjusting the position of the tripping coil, I tested the Breaker and the problem was gone.

The thing I Want to Share is that the circuit breaker has a complicated mechanism inside it. One component failure can lead to malfunction of the breaker. I have several experience troubleshooting the mechanical side of The breaker. If the breaker behaving in the way it shouldn't without any protection relay appear including lockout 86, we will suspect the breaker itself.

Hope it helps
Riko