1600amp Square D tripping

R

Relisys190

Member
Location
USA
Occupation
Building Operator
Need help ! I have a 12 story property fed by two switch gears. A 3000 amp main and a 1600 amp secondary. Built in 1984.

Backstory : we were hit hard by hurricane Helene storm surge . We had a phase to phase event in conduit between utility transformer and our gears. There are 13 parallel runs. 8 feed the 3000 and 5 feed the 1600. Two wires phased together in the 3000 side and 2 wires phased in the 1600 side. Salt water from conduits shot into each cabinet. The building was put on two generators to keep operation going.

Both breakers were removed and tested the 1600 was replaced after finding voltage leak by when open and a refurnished unit like for like was purchased . We finally had all 52 feeders cables replaced by insurance 6000ft of wire. Long story short we re energized with utility just this passed weekend after 7 months on generator power.

All is well with the 3000 side. This feeds my buss riser to the building, all floors and main elevators, and a 480 volt 400 amp disconnect for chiller 1.

1600 feeds my ATS , high voltage 277 garage lighting distribution and garage elevators panels, 400 amp disconnect for chiller 2 and a 480 / 277 volt sub panel for chiller plant pump motors and cooling tower drives.

The 1600 keeps tripping. What I thought originally was garage ground floor lighting submerged by storm surge causing issues . I have completely isolated the fused disconnect for that (HG 1/HG2 panels) by turning it off The 1600 switch remained stable for hours until I fired up chiller 2. Upon loading up. The breaker tripped again…. I’m at a loss. Are the ground fault settings too sensitive ? Is the shunt trip activating by itself ?

I am not an electrician, I operate the site as the building engineer. Any help or ideas would be great !

-M
 
You will need an engineered study for the proper settings. The generator transferswitch should be a four pole, meg gen neutral to building neutral to verify no leakage between the two. When does it trip? Right at dark? Parking lot lighting that is external to the parking deck coming from a different panel?
 
hillbilly1 said:
You will need an engineered study for the proper settings. The generator transferswitch should be a four pole, meg gen neutral to building neutral to verify no leakage between the two. When does it trip? Right at dark? Parking lot lighting that is external to the parking deck coming from a different panel?
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This morning in anticipation of having tenants back tomorrow it tripped as soon as I loaded up the chiller 2 fed from the 1600. Within 5 mins it tripped. This was with the garage fused disconnect completely isolated And OFF.

The chiller feed is 400 amp disconnect fed from this switch gear. Just to get the building running I re-hooked the generator cables back to my chiller plant to have stable power for hvac tomorrow.
 
Disconnects are :

ATS.

Chiller plant sub panel ( pump motors / cooling tower drives )

Chiller 2 (400 amp)

HG1 / HG 2 garage lighting / property lighting.
 

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Relisys190 said:
This morning in anticipation of having tenants back tomorrow it tripped as soon as I loaded up the chiller 2 fed from the 1600. Within 5 mins it tripped. This was with the garage fused disconnect completely isolated And OFF.

The chiller feed is 400 amp disconnect fed from this switch gear. Just to get the building running I re-hooked the generator cables back to my chiller plant to have stable power for hvac tomorrow.
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Perhaps a jumper between the neutral and ground was accidentally left In when it was on generator? Chiller mounted at ground level? Or on top of the building?
 
hillbilly1 said:
Perhaps a jumper between the neutral and ground was accidentally left In when it was on generator? Chiller mounted at ground level? Or on top of the building?
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Chiller plant at ground level. It was under 52” of storm surge in Oct. However the plant has been running stable on a 1meg generator for 7 months. I put the plant back on generator feed this afternoon when the 1600 kept tripping during compressor load up. We just re-energized with TECO utility May 17th. Something is not right. Either the used 1600 is bad ? (It was tested and came with a test sheet but no warranty. $19,000 should be GOOD USED! ).

Problem is to have this breaker retested we have to deenergize with TECO AGAIN.

I think I will have an PE engineer look at the trip settings on the front of the breaker
 
Relisys190 said:
Chiller plant at ground level. It was under 52” of storm surge in Oct. However the plant has been running stable on a 1meg generator for 7 months. I put the plant back on generator feed this afternoon when the 1600 kept tripping during compressor load up. We just re-energized with TECO utility May 17th. Something is not right. Either the used 1600 is bad ? (It was tested and came with a test sheet but no warranty. $19,000 should be GOOD USED! ).

Problem is to have this breaker retested we have to deenergize with TECO AGAIN.

I think I will have an PE engineer look at the trip settings on the front of the breaker
Click to expand...
Was the previous settings recorded? It may have been turned up from factory settings, which the replacement would be set at minimum.
 
I appreciate the input !! I certainly have learned a lot about electrical the passed 7 months of this. I’ve been in this field 13 years but never dealt with a catastrophic event like this. It’s been a good learning experience 100%.

-M
 
It sounds like there could be a wiring problem with the "new" breaker and its separate neutral CT. Was this CT replaced at the same time as the breaker? Was the breaker and neutral CT commissioned by an actual GF performance test as opposed to a simple functional test using the button on the front of the breaker?

It is probably less of a hassle to have a planned outage to deal with this, than to continue having unplanned outages.
 
jim dungar said:
It sounds like there could be a wiring problem with the "new" breaker and its separate neutral CT. Was this CT replaced at the same time as the breaker? Was the breaker and neutral CT commissioned by an actual GF performance test as opposed to a simple functional test using the button on the front of the breaker?

It is probably less of a hassle to have a planned outage to deal with this, than to continue having unplanned outages.
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Good point, possibly CT installed or wired backwards.
 
hillbilly1 said:
Was the previous settings recorded? It may have been turned up from factory settings, which the replacement would be set at minimum.
Click to expand...
I have confirmed the “new” refurbished breaker was delivered and installed at minimums.

I have compared the old to new settings but I will not be the one changing them without a study of some sort. The vendor who delivered mentioned the settings also. For liability purposes they deliver at minimum
 
jim dungar said:
It sounds like there could be a wiring problem with the "new" breaker and its separate neutral CT. Was this CT replaced at the same time as the breaker? Was the breaker and neutral CT commissioned by an actual GF performance test as opposed to a simple functional test using the button on the front of the breaker?

It is probably less of a hassle to have a planned outage to deal with this, than to continue having unplanned outages.
Click to expand...
The CT was not replaced. It is still on the neutral buss. I recall the electricians talking about it as they wired it up, but was wired up the same as the last breaker. The shunt trip module was swapped from the old breaker to the “new breaker.
 
These are not settings I understand nor will I be adjusting anything without an electrician

-M

OLD breaker uninstalled (with blue sticky note )
IMG_6986.jpeg





“new” refurbished unit installed.

IMG_6987.jpeg
 
Relisys190 said:
The CT was not replaced. It is still on the neutral buss. I recall the electricians talking about it as they wired it up, but was wired up the same as the last breaker. The shunt trip module was swapped from the old breaker to the “new breaker.
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The plot thickens, is there an outside EPO switch? I had a Lowes that was randomly tripping the ground fault main after a hurricane. Found the EPO switch enclosure was full of salt water.
 
Relisys190 said:
These are not settings I understand nor will I be adjusting anything without an electrician

-M

OLD breaker uninstalled (with blue sticky note )
View attachment 2577693





“new” refurbished unit installed.

View attachment 2577695
Click to expand...
Quite possible it’s tripping on instantaneous, a large compressor kicking on could do it. That’s probably why the original breaker was turned up.
 
Relisys190 said:
I have confirmed the “new” refurbished breaker was delivered and installed at minimums.

I have compared the old to new settings but I will not be the one changing them without a study of some sort. The vendor who delivered mentioned the settings also. For liability purposes they deliver at minimum
Click to expand...
Why can't you use the settings from the old breaker? A study is nice but why mess with what used to work?
At minimum GF setting your breaker probably does not coordinate with any OCPD much larger than 30A. So the main breaker will trip before most branch breakers can clear the fault.
 
Relisys190 said:
These are not settings I understand nor will I be adjusting anything without an electrician
Click to expand...
Right now your breaker is set as an 800A breaker (Long Time Pickup setting) with a GF pickup of 320A. No wonder it trips.

Most of the service shops I dealt with would have put your old settings into the new breaker. They would have required a study if you wanted different settings.
 
hillbilly1 said:
The plot thickens, is there an outside EPO switch? I had a Lowes that was randomly tripping the ground fault main after a hurricane. Found the EPO switch enclosure was full of salt water.
Click to expand...
Yes, there is an EPO switch, but it is in the main fire control room above ground level in
jim dungar said:
Right now your breaker is set as an 800A breaker (Long Time Pickup setting) with a GF pickup of 320A. No wonder it trips.

Most of the service shops I dealt with would have put your old settings into the new breaker. They would have required a study if you wanted different settings.
Click to expand...
thank you for the clarification. I will discuss this with the electrician when they come on site to adjust. I’m assuming the breaker needs to be in the open position prior to adjustment?
 
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