GE switchgear tripping

[Electrician1]

Working on a 2000 amp 480 volt ge spectra series switchgear that trips randomly along with 1200 amp ats breaker no loss of utility power and not during a storm. The 3 times that they have tripped have been different times of day and night. We put a meter on it for a week never loss power no spike in amperage. Had a drop in voltage for a brief moment on c phase 220 volts instead of 277. There is ground fault units that don't appear be tripped. Does anybody have any insight on this?

 

[jim dungar]

When was the last time this breaker was tested and maintained?

 

[Electrician1]

Probably never if I had to guess. It is 2 separate breakers/ fused switches tripping at the same time

 

[jim dungar]

My experience is that when breakers, in series, randomly trip there is often an issue with the Ground Fault (GF) protection system, either poorly coordinated settings, lack of maintenance, or failing components.

If GF settings are at minimum it is possible that a fault on a 30A branch circuit, like a failing ballast, can cause a 2000A device to open.

 

[ptonsparky]

57 volts seems like a lot of drop on one phase. Connections? Fault?

 

[Electrician1]

Thank you. They are both set on 1200 I'm not sure what they should be set on. There is a switch on the ground fault units if the ground fault was to trip wouldn't that have to be reset to close the breaker?

 

[Electrician1]

57 volts seems like a lot of drop on one phase. Connections? Fault?

Yes 57 volts is a lot not sure why that would happen maybe utility. On low power I think the generator would start and not trip any breakers

 

[jim dungar]

Thank you. They are both set on 1200 I'm not sure what they should be set on. There is a switch on the ground fault units if the ground fault was to trip wouldn't that have to be reset to close the breaker?

How do you know they are working properly if they have not been tested.
GF protection usually has settings for magnitude and time.

 

[jim dungar]

Yes 57 volts is a lot not sure why that would happen maybe utility. On low power I think the generator would start and not trip any breakers

How long does the drop last? A short circuit can cause voltage to drop.

 

[Electrician1]

How do you know they are working properly if they have not been tested.
GF protection usually has settings for magnitude and time.

I don't know that. I do know the GF has a normal and a tripped switch the switch is not showing tripped when the breaker trips out

 

[Electrician1]

How long does the drop last? A short circuit can cause voltage to drop.

Idk our meter isn't real precise on time length

 

[jim dungar]

I don't know that. I do know the GF has a normal and a tripped switch the switch is not showing tripped when the breaker trips out

If a 1200A or 2000A device trips and can be reset, without there being visible smoke and burning someplace in the system, it is likely not operating at or above its full rating.

If you cannot afford an outage for testing, you will likely need to continue affording unplanned ones.

 

[jim dungar]

Idk our meter isn't real precise on time length

You need a meter that can provide magnitude, phase angles, and duration of all 3-phases voltages and currents at the same time.

 

[Electrician1]

How long does the drop last? A short circuit can cause voltage to

If a 1200A or 2000A device trips and can be reset, without there being visible smoke and burning someplace in the system, it is likely not operating at or above its full rating.

If you cannot afford an outage for testing, you will likely need to continue affording unplanned ones.

There's no burning or smoke seems to reset fine. We're supposed to have a coordination study done. But I would like to get it resolved asap. I'm going to check into getting some testing done on it not sure it can be done since it's just a fused switch it's not like a modern breaker

 

[jim dungar]

There's no burning or smoke seems to reset fine. We're supposed to have a coordination study done. But I would like to get it resolved asap. I'm going to check into getting some testing done on it not sure it can be done since it's just a fused switch it's not like a modern breaker

If the fuses are not "blowing" it is even more likely the problem is with the GF system.
I have seen many GF installations that were done improperly, usually N-G bonds on the wrong side of the GF sensor, resulting in nuisance trips when enough equipment was brought on line. One case that comes to mind were duct heaters at an insurance company headquarters.

You need appropriate settings and proper testing/commissioning of the GF system. Many times the installing contactor simply pushes the 'test button' on the GF relay and says "see it works". In my opinion the NEC requires the complete GF system to be tested not just the relay.

 

[Electrician1]

If it was the GF wouldn't I have to reset the GF before I reset the breaker? The GF stays normal while this is happening

 

[hillbilly1]

Is there a phase loss monitor? I have seen those used before on a gear, but not very often. A phase loss or undervoltage would trigger the shunt trip mechanism. Since you are recording a severe voltage drop, that might be the case. Is there an EPO switch outside the building? Since it appears random, it may be some vandals causing trouble.

 

[jim dungar]

If it was the GF wouldn't I have to reset the GF before I reset the breaker? The GF stays normal while this is happening

So you have a 2000A fusible switch with a shunt trip mechanism that has a GF relay that does not need to be reset.

As hillbilly said, are there other protective relays controlling the shunt trip, maybe an Arc Flash 'reduction' switch?

 

[Ziyad Alahrbi]

I have some questions.
Was the system operating healthy before?
Is there any relay activated?

You might need to check protection auxiliary power.
Check mechanical relays.
Check instruments output like CT and VT.
Check if system is tripping after motor starting.
GF relays are very sensitive.

Last option mechanical integrity test for breakers.

Regards.
Ziyad Alharbi