A customer is having a problem with some generators. I'll try and explain:
Two generators are paralleled, I think they are 550kw each. Gen #1 is adjacent to the transfer gear, Gen # 2 is in the next room. Gen #1 is not equipped with an output breaker, the breaker in the ATS is serving that purpose. Gen#2 is equipped with a 1000A output breaker in an adjacent control cabinet in addition to the breaker in the ATS. Either these two units once operated individually, or Gen #1 and the parallel gear were added to the existing Gen#2. I say this because I am told the controls for Gen#2 are "abandoned".
Here's the problem (as it's been explained to me):
When the generators run, #1 goes online first. Before Gen#2 comes online the breaker at the generator trips. This is the breaker whose controls are "abandoned". It would seem that the units are not synchronizing so #2 drops out. Or... the "abandoned" controls for #2 are looking for a signal from the ATS that they're not getting, so the breaker drops out.
Here's the solution that I've been asked to provide:
Eliminate the tripping breaker. Just take it out and make it go away. I can do this easily enough and just splice the conductors, thereby eliminating the local disconnecting means and the overcurrent protection.
Here's some questions:
Am I required to provide a disconnecting means at Gen#2? Sec. 445.18 requires the gen to be "equipped" with a disconnect. If the output conductors enter another room before landing on the breaker, is the gen "equipped" with a disconnect? Maybe I can replace the breaker with a molded case switch, but do the output conductors require overcurrent protection before they leave the room?
Overcurrent protection and the controls are provided by the ATS. If there is a problem with the generators synchronizing then the breaker that remains in the ATS should be the one to react.
What else could be causing this breaker to trip?
Thank you.
Two generators are paralleled, I think they are 550kw each. Gen #1 is adjacent to the transfer gear, Gen # 2 is in the next room. Gen #1 is not equipped with an output breaker, the breaker in the ATS is serving that purpose. Gen#2 is equipped with a 1000A output breaker in an adjacent control cabinet in addition to the breaker in the ATS. Either these two units once operated individually, or Gen #1 and the parallel gear were added to the existing Gen#2. I say this because I am told the controls for Gen#2 are "abandoned".
Here's the problem (as it's been explained to me):
When the generators run, #1 goes online first. Before Gen#2 comes online the breaker at the generator trips. This is the breaker whose controls are "abandoned". It would seem that the units are not synchronizing so #2 drops out. Or... the "abandoned" controls for #2 are looking for a signal from the ATS that they're not getting, so the breaker drops out.
Here's the solution that I've been asked to provide:
Eliminate the tripping breaker. Just take it out and make it go away. I can do this easily enough and just splice the conductors, thereby eliminating the local disconnecting means and the overcurrent protection.
Here's some questions:
Am I required to provide a disconnecting means at Gen#2? Sec. 445.18 requires the gen to be "equipped" with a disconnect. If the output conductors enter another room before landing on the breaker, is the gen "equipped" with a disconnect? Maybe I can replace the breaker with a molded case switch, but do the output conductors require overcurrent protection before they leave the room?
Overcurrent protection and the controls are provided by the ATS. If there is a problem with the generators synchronizing then the breaker that remains in the ATS should be the one to react.
What else could be causing this breaker to trip?
Thank you.