1600amp Square D tripping

Elect117 said:
It might be time to hire a good industrial electrician or an engineer to come by and evaluate some of what you have going on. I can't tell if there are glaring issues or if I am only getting / understanding things partially. A 1600A breaker wouldn't be protecting a 275kW generator under normal circumstances. Potentially if it was only a back up for the fire pump. I wouldn't suggest replacing that breaker without consulting an engineer or experienced electrician any way since it is for the fire pump and emergency systems. There needs to be some coordination with the fire pump.
Click to expand...
I think somewhere back in the beginning of this thread, the OP said it was feed from a sub breaker from the 1600 amp main?
 
I ran into a problem similar to yours years back on a square d 1600a main. It had a phase loss protection system that had failed, and made the main trip. It was below the main in the gear on the utility feed side of the enclosure.
 
Update : The breaker vendor came back onsite and adjusted the long time delay to FULL. (24 sec ). We energized just the condenser and chill water pumps and watched the breaker behavior with an amp meter on the 1 phase of the sub panel downstairs. The 2 pumps are drawing 55amps total ( each pump has a 60 amp 480volt 3 phase breaker)

The 1600 amp main immediately started flashing red 90% load. And then Shifted over to full lit (100% load) which at that time the timer begins on long time.

The breaker tripped just under 1 min running two pump motors ….

They are leaning towards a bad trip unit. Thoughts ?
 
Sure seems like a breaker problem. It may sound obvious, but long-time settings are for "slow" overloads. If the long-time is being activated at 55A there's a problem.

I'd swap it.
 
Relisys190 said:
Salt water from conduits shot into each cabinet.
Click to expand...
Man thats scary, a plant guy I know had a situation like that up in NJ, storm water got into into some gear.
A big EC outfit was hired to test & clean the system for the insurance, everything was fine but later one feeder breaker kept tripping, I think it was not a very large breaker 400A or 600A, he checked it out checks out OK reset the breaker closed the door to the electrical room and boom the breaker exploded right as the door latched.

It was about month or two past his retirement, they kept trying to bring him back as a consultant post retirement and after that he decided to stay retired.. He said the equipment should have been retired when he did.
So just stay safe out there.
 
Update : they (breaker vendor) are sending an engineer in the AM to confirm the neutral CT on my gears bus bar and its terminals on the lower section of the breaker. He has a suspect theory it is wired Improperly. We shall find out tomorrow.

I’m not all butterflies and kittens opening the enclosure while energized but he is bringing his hot suit. I’ll wait outside the room!
 
Relisys190 said:
Update : they (breaker vendor) are sending an engineer in the AM to confirm the neutral CT on my gears bus bar and its terminals on the lower section of the breaker. He has a suspect theory it is wired Improperly. We shall find out tomorrow.

I’m not all butterflies and kittens opening the enclosure while energized but he is bringing his hot suit. I’ll wait outside the room!
Click to expand...
I thought this back in post #11.
This is an extremely common installation error.
This
 
jim dungar said:
I thought this back in post #11.
This is an extremely common installation error.
This
Click to expand...
Would be excellent if this is the case. Although he did say they will need a planned outage to make changes or replace the CT on the bus if needed. Either way we are moving in the right direction !
 
Another item that was brought up was my previous breaker was a PEC1600 model where as the new one is a PXF. He said the PXF model is very critical for the CT to be wired up correctly. I am not an electrician nor an electrical engineer. But it makes sense to me. Let’s hope for the best outcome.

-M
 
Relisys190 said:
Another item that was brought up was my previous breaker was a PEC1600 model where as the new one is a PXF. He said the PXF model is very critical for the CT to be wired up correctly. I am not an electrician nor an electrical engineer. But it makes sense to me. Let’s hope for the best outcome.

-M
Click to expand...
The PEC was a 100% rated breaker the PXF is an 80% one. Not a problem if your load is less than 1280A.
 
I've had a similar situation before.

A new breaker kept tripping at 1200A load; and guess what the ground fault pick-up setting was? 1200A.

There was a bad neutral CT / connection in the breaker, so it thought that any amount of phase load was a ground fault. When it hit 1200A, it tripped.
 
There can be a lot CT issues out there, one was
A brand new shopping center where the ct was installed backwards on the buss. Another was a new Verizon switching station where the ct was not hooked up, breaker would not set. Another was a distribution center where every time the air compressor started up, it tripped the main. The CT was a window type in top of the gear, a couple of phases were pulled short, and were routed below outside the CT.
 
Relisys190 said:
Is it normal for a breaker to trip with a momentary power fluctuation ?
Click to expand...
Absolutely! When power disconnects on a rotating motor, the residual magnetism in the motor windings briefly turn it into a generator until the magnetic fields collapse, which can be seconds in a large motor. If the source then reconnects again during that time, then you have the equivalent of two power generators connecting out of synch, and the resulting current (and torque) spike can be MUCH higher than the “normal” magnetizing inrush current. I’ve seen it shear off the shaft of a 600HP motor on a high pressure aeration blower.

If this is a common occurrence, you need to implement a restart delay of long enough to allow the motor magnetic fields to dissipate, usually 5-10 seconds is enough.
 
You must log in or register to reply here.
Top