Problem with Automatic Synchronizer/ Permissive Relay

[aganger691]

So to start out, I'm more on the mechanical side of the house and my experience with paralleling diesel sets is strictly with hydrualic govenors. I'm working on a two gen set of Cat 3412D's pushing a 500KW gen each. These units were installed in the early 80's and the only documentation that I have is the cut sheets from the install. During my most recent no load test gen 2 had trouble synching up when coming on line. Twice it attempted to synchronize before coming up fully. It was almost as if the contacts were chattering or the automatic synchronizer was hunting for proper voltage or phase requirements. I'm going to run them again this afternoon to see if the problem persists. Any comments or advice would be much appreciated.

 

[davidbeach]

I don't know at this point, but I do know that the more more detail you can provide the better the response will be. Even hunting could be different things, is it hunting on the voltage side or the phase angle side? Frequency/phase angle comes from the governor/throttle while voltage comes from the AVR/Excitation system.

 

[aganger691]

After a second run watching the voltage and frequency of gen 2 I'm confident that the readings were steady enough and the rpm was constant enough to assure me that the unit isn't hunting. I also paid close attention to the circuit breaker on the front of the remote control panel, this is where I intially noticed the lagg, this time around I noticed that again it tried twice to throw over and didn't make full contact until the third attempt. The circuit breaker is a GE 120 volt 6 amp breaker that, for my best guess, puts the gen on the bus. My guess is that it's showing it's age and starting to go. Does this sound probable? Thanks for a ll the help.

 

[davidbeach]

6 amp? Surely a typo.

 

[dpc]

6A, 120V breaker? Did you mean relay?

 

[aganger691]

Confused me too, pretty small for a bus transfer. Best I can figure it's just a smaller device to drive the large breaker behind it. Reviewing the drawings now.