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Synchronizing a Generator
Synchronizing a generator to a grid.

When synchronizing a generator to an existing grid, it's KVR's increase and the other online generators KVR's decrease and their breakers trip. What could be possible causes, as I have check all wiring and replaced the AC module?

1 out of 2 members thought this post was helpful...

It is very common practice for generator set packagers to program the control system to annunciate an alarm for ANY condition that results in a trip of either the prime mover or the generator breaker. WHAT alarms are being annunciated when the breskers are tripping???

If there aren't any alarms from the control system then there SHOULD be flags visible on one or more generator protective relays to indicate the resdon the generator breaker was opened.

Finally, is there any signals coming from an external control system, possibly called a Power Management System (PMS) to the generator prime mover control systems and/or the generator exciter control systems? If so, possibly there could be a problem with the external control system.

But, really, there's not enough information to make any more guesses. Best of luck!

Please write back to let us know what you find and how you resolve the issue.

If the voltage and frequency are 'in sync' then everyone should be happy. I have seen a faulty voltage signal (improperly set PPT causing the voltage to appear lower than it really was.) In my case, when the breaker closed, it was at a higher voltage causing the nearby generators to see a sudden VAR difference. Your situation sounds similar. The generator breaker closes with a significant voltage difference causing the other generators to hit V/HZ or other trip. You do need to know the actual cause of the trips and ensure the voltages are reading correctly.

Good Luck

Has this installation ever worked correctly, or is this a new installation??

If new, likely the phase rotation and order of the varying gensets are not the same as each other or the utility. Synchronization can only take individual generators so far out of native phase and frequency to meet line conditions, too much difference will cause issues.

If this is a previously working installation, refer back to the other answers you've received regarding phase-frequency detection.