Gen Breakers Failed to close just "Click"

[Warrengarber]

I was called out to a customers facility a couple of nights ago. The phone conversation starts as they usually do. Have not heard from you in a while so something must be wrong. He said that none of the generator breakers are closing "just clicking" after manually starting the gens.

My first question was why are you manually start the gens and the response was that they were trying something. I then asked if the battery plant was up and they then responded that the battery plant was in alarm and only had about 20vdc instead of the required 24vdc. Low but not really low. I would expect that the closing coils would do more then "click" at 20vdc. So I took a trip to the site.

When I arrived I was told the whole story. A new ASCO PLC was installed sense my last visit but it was on line and working for the last year with no issues. That morning when performing a monthly transfer run the PLC failed to start the gens they then noticed that the battery station was in alarm and reset the charger.

I looked at the charger and saw that the batteries were replaced and that the charger was a 6amp unit. ASCO informed me that the charger should be at least a 10amp charger and it should be replaced. In the mean we manually fired up gen 1 and sent the signal for the gen 1 breaker to close it "clicked" and the gen shutdown.

The generator technician and I decided to just rack the gen breaker out and back in to see if it does anything. There were no flags and no bell alarm buttons popped on the breaker but it was worth a try. So I racked the breaker out and back in fired up the gen and boom the breaker closed.

We shut it down racked out and back in the gen 2 and 3 breakers then manually started all three gens. Boom gen 1 closed, click gen 2 failed and shutdown and boom gen 3 closed. Well 2/3 is not good enough for a credit card company so we shut down gens 1 and 3 and I racked the gen 2 breaker back out and in to try it one more time. It did not work.

We all met with facility staff and it was decided that one of their guys would stay on watch that night to manually start the two gens if needed and someone would go get a new 10amp charger that was located in the morning. I called yesterday to see how it was going and they had installed the new charger but something was dragging the 24vdc plant down.

They lifted the trip coil circuit for gen 2 just to see if it was the cause of the drain while I was on the phone and it did not make a change so I knew it was not the breaker causing the issue. I just talked to the ASCO tech and a burnt wire was found in the PLC that was for generator paralleling in the dc circuit and now everything is operating as it should.

I just wanted to share this story because things are not always as they seam and with complicated systems it could just be a burnt wire causing an entire system to fail. I think they now have a spare 6amp battery charger on site. You always have to look outside the box.

[nolanholt]

I was called out to a customers facility a couple of nights ago. The phone conversation starts as they usually do. Have not heard from you in a while so something must be wrong. He said that none of the generator breakers are closing "just clicking" after manually starting the gens. My first question was why are you manually start the gens and the response was that they were trying something. I then asked if the battery plant was up and they then responded that the battery plant was in alarm and only had about 20vdc instead of the required 24vdc. Low but not really low. I would expect that the closing coils would do more then "click" at 20vdc. So I took a trip to the site. When I arrived I was told the whole story. A new ASCO PLC was installed sense my last visit but it was on line and working for the last year with no issues. That morning when performing a monthly transfer run the PLC failed to start the gens they then noticed that the battery station was in alarm and reset the charger. I looked at the charger and saw that the batteries were replaced and that the charger was a 6amp unit. ASCO informed me that the charger should be at least a 10amp charger and it should be replaced. In the mean we manually fired up gen 1 and sent the signal for the gen 1 breaker to close it "clicked" and the gen shutdown. The generator technician and I decided to just rack the gen breaker out and back in to see if it does anything. There were no flags and no bell alarm buttons popped on the breaker but it was worth a try. So I racked the breaker out and back in fired up the gen and boom the breaker closed. We shut it down racked out and back in the gen 2 and 3 breakers then manually started all three gens. Boom gen 1 closed, click gen 2 failed and shutdown and boom gen 3 closed. Well 2/3 is not good enough for a credit card company so we shut down gens 1 and 3 and I racked the gen 2 breaker back out and in to try it one more time. It did not work. We all met with facility staff and it was decided that one of their guys would stay on watch that night to manually start the two gens if needed and someone would go get a new 10amp charger that was located in the morning. I called yesterday to see how it was going and they had installed the new charger but something was dragging the 24vdc plant down. They lifted the trip coil circuit for gen 2 just to see if it was the cause of the drain while I was on the phone and it did not make a change so I knew it was not the breaker causing the issue. I just talked to the ASCO tech and a burnt wire was found in the PLC that was for generator paralleling in the dc circuit and now everything is operating as it should. I just wanted to share this story because things are not always as they seam and with complicated systems it could just be a burnt wire causing an entire system to fail. I think they now have a spare 6amp battery charger on site. You always have to look outside the box.

Good info to have. Not always the obvious thing that could be the issue. It's strange though that racking the breakers out then back in could have produced a different outcome. Electrical gear seems to be its own strange form of black magic.