1600amp Square D tripping

[jim dungar]

Yes, there is an EPO switch, but it is in the main fire control room above ground level in

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?

No, but it is advised. The adjustments can be made at anytime, but sometimes the breaker will revert to its lowest pickup points as you move the selector between settings. This can cause an unexpected trip if there is adequate loading on the breaker.

 

[Relisys190]

Update : They have adjusted the settings onsite twice. I’ve come in both times the following morning EARLY and wired up the chiller plant (after un-wiring the generator). I set the plan to run, pumps come online , and about 20 seconds later the chiller compressor motor comes online After 50 seconds of running and well beyond the inrush current occurs. The breaker trips again.

The chiller and its pumps have been running fine on generator power for 7 months.

The inrush current for the carrier chiller is 750 amps for 1-2 seconds.

The breaker is now set for (1.0) 1600 amp. With a 9600 amp 7 second delay. (Long time) and it trips after 50 seconds of starting the chiller.

What is going on with this breaker ? If it was seeing ground fault would it not be instant once the 400 amp fused disconnects feeding the plant were energized ?

 

[Relisys190]

Here is what the 1600 amp supplies downstairs. (with two separate 400amp fused disconnects ). This is what I am currently powering with temporary generator power (450kv running at 480volt)

The panel on the left has 6 breakers.
2 chilled water pump
2 condenser water pumps
2 cooling tower VFD fan motor drives.

The large knife switch disconnect on the right feeds the chiller directly with 480.

Only 1 chilled water and 1 condenser water pump motor annd both VFD’s are starting with this carrier chiller. The cooling tower VFD’s are running 0 hz until needed to cool the loop.

 

[jim dungar]

Your original breaker did not have a short time protective function but your new breaker does. A trip at 50 sec looks like it would be from this function. You would need to compare your settings to the trip curve to see how the breaker should behave.
Do you have a recording ammeter so you can see how much current is actually being drawn?
Sometimes generators cannot supply the full amount of current possible from the utility. When this happens they may reduce their voltage, in effect becoming a soft starter.

 

[Relisys190]

Your original breaker did not have a short time protective function but your new breaker does. A trip at 50 sec looks like it would be from this function. You would need to compare your settings to the trip curve to see how the breaker should behave.
Do you have a recording ammeter so you can see how much current is actually being drawn?
Sometimes generators cannot supply the full amount of current possible from the utility. When this happens they may reduce their voltage, in effect becoming a soft starter.

I do not specifically have a recording ammeter. I will check if my Klein has a max amp function to see what the current spikes too on a single phase with the clamp over the feed wire.

If the short time protection function is causing the trip should the breaker vendor recommend increasing the settings ?

 

[Relisys190]

Also here is the test sheet they supplied with the refurbished breaker. It was just tested in March prior to us going back online with Utility power.

 

[don_resqcapt19]

I do not specifically have a recording ammeter. I will check if my Klein has a max amp function to see what the current spikes too on a single phase with the clamp over the feed wire.

If the short time protection function is causing the trip should the breaker vendor recommend increasing the settings ?

That should be done by an engineer who has studied the system and the equipment.

 

[zbang]

I do not specifically have a recording ammeter. I will check if my Klein has a max amp function to see what the current spikes too on a single phase with the clamp over the feed wire.

I think you may need one, or to at least watch the meter over the minute or so it takes to trip and write down the readings every couple of seconds.

 

[jim dungar]

If the short time protection function is causing the trip should the breaker vendor recommend increasing the settings ?

As Don said in #27, you need someone familiar with your facility not someone who knows the breaker, although it is possible the breaker vendor employs this type of engineer.

 

[Relisys190]

Thank you for all your feedback and input. We will get to the bottom of this. Until then, chiller plant will be run on diesel power

I am so glad that at least our 3000 amp is stable and without issue powering the buss riser. Running two Gens for all those months after Helene was sort of a nightmare ..

 

[Relisys190]

Update : The vendor that sold us the breaker is coming out again tomorrow morning to remain onsite while I wire the plant back up to building power and monitor the breaker behavior while energizing the chiller. That is helpful.

On another note the area suffered a minor power blip this morning from utility , all three of my sites nearby momentarily went down and came back online within seconds however this problem breaker tripped. Is it normal for a breaker to trip with a momentary power fluctuation ? The 3000 amp did not trip only the 1600.

I’m at a loss.

 

[Elect117]

Update : The vendor that sold us the breaker is coming out again tomorrow morning to remain onsite while I wire the plant back up to building power and monitor the breaker behavior while energizing the chiller. That is helpful.

On another note the area suffered a minor power blip this morning from utility , all three of my sites nearby momentarily went down and came back online within seconds however this problem breaker tripped. Is it normal for a breaker to trip with a momentary power fluctuation ? The 3000 amp did not trip only the 1600.

I’m at a loss.

That would be a inrush trip or instantaneous trip setting. It can be normal for larger manufacturing facilities to have their main trip when a power outage occurs if they have large motors and large transformers. You can add soft starters or program delays to avoid it rather than making changes to the MCB which can effect more than just the initial powering on. It sounds like you run 24/7 or was this during normal business hours?

If you have a power outage and have people on site, just have them turn all the manufacturing feeder breakers off, keep the lights turned on, and it shouldn't trip. Then in a orderly fashion, turn each feeder on one by one. If it is still tripping then the MCB is still having issues. Whether that is settings or something else will require more looking into.

 

[Relisys190]

That would be a inrush trip or instantaneous trip setting. It can be normal for larger manufacturing facilities to have their main trip when a power outage occurs if they have large motors and large transformers. You can add soft starters or program delays to avoid it rather than making changes to the MCB which can effect more than just the initial powering on. It sounds like you run 24/7 or was this during normal business hours?

If you have a power outage and have people on site, just have them turn all the manufacturing feeder breakers off, keep the lights turned on, and it shouldn't trip. Then in an orderly fashion, turn each feeder on one by one. If it is still tripping then the MCB is still having issues. Whether that is settings or something else will require more looking into.

Currently the 1600 is ONLY energizing my ATS for emergency power transfer to this office building. The other three fused disconnects fed from the 1600 are locked out tagged out.

 

[Elect117]

Currently the 1600 is ONLY energizing my ATS for emergency power transfer to this office building. The other three fused disconnects fed from the 1600 are locked out tagged out.

I am not familiar with you set up so take what I said with a grain of salt. It seems like I might have misunderstood.

Do you have a an emergency power source hooked up to the ATS?

 

[Relisys190]

I am not familiar with you set up so take what I said with a grain of salt. It seems like I might have misunderstood.

Do you have a an emergency power source hooked up to the ATS?

Yes our standby built in generator gets a signal to run when the ATS loses it’s normal power source (the 1600)

 

[jim dungar]

Currently the 1600 is ONLY energizing my ATS for emergency power transfer to this office building. The other three fused disconnects fed from the 1600 are locked out tagged out.

Your original breaker was extremely old, maybe around 40 years. Your replacement breaker is not much younger.

When you purchased your breaker did it come from a certified refurbishing company, or was it bought from someone that had one laying around?
In either case, when you had it installed was its tripping curve tested.

Generally a breaker, without load, should not trip on a power loss.
Yes it is possible for breakers to have undervoltage tripping, but you would have some control wiring if yours has this module.

 

[Elect117]

Yes our standby built in generator gets a signal to run when the ATS loses it’s normal power source (the 1600)

What size is the generator? Is there a load bank? What is your typical demand on what it is feeding?

Has the location added load since the generator was first installed?

Your original breaker was extremely old, maybe around 40 years. Your replacement breaker is not much younger.

When you purchased your breaker did it come from a certified refurbishing company, or was it bought from someone that had one laying around?
In either case, when you had it installed was its tripping curve tested.

Generally a breaker, without load, should not trip on a power loss.
Yes it is possible for breakers to have undervoltage tripping, but you would have some control wiring if yours has this module.

I was thinking outage, genset starts up, programed time delay, and then it is closing in on large transformers or motors creating that transient/inrush trip. But if it is just feeding a office building, then I don't know how large of a step down transformer would be needed for it to trip the ATS's breaker and not the generator's. It would have to be close to 400kVA or larger right? (I am assuming it goes from 480 to 208 3ph for the office).

You could be right. Maybe they got sold a bad replacement / refurbished breaker.

 

[Relisys190]

Your original breaker was extremely old, maybe around 40 years. Your replacement breaker is not much younger.

When you purchased your breaker did it come from a certified refurbishing company, or was it bought from someone that had one laying around?
In either case, when you had it installed was its tripping curve tested.

Generally a breaker, without load, should not trip on a power loss.
Yes it is possible for breakers to have undervoltage tripping, but you would have some control wiring if yours has this module.

Unfortunately there was no testing after it was installed and energized. It was delivered and installed with a test sheet from the supplier. I attached a photo of the test sheet above. The only control wiring I know of is on the lower section for the shunt trip module. I’m hoping tomorrow when the supplier is onsite they can see what seems to be happening. Yes the breaker style is very old.

Would have been much easier if forensics insurance tech would have just said “replace it all” after the storm. This has been very frustrating as the building operator.

 

[Relisys190]

What size is the generator? Is there a load bank? What is your typical demand on what it is feeding?

Has the location added load since the generator was first installed?



I was thinking outage, genset starts up, programed time delay, and then it is closing in on large transformers or motors creating that transient/inrush trip. But if it is just feeding a office building, then I don't know how large of a step down transformer would be needed for it to trip the ATS's breaker and not the generator's. It would have to be close to 400kVA or larger right? (I am assuming it goes from 480 to 208 3ph for the office).

You could be right. Maybe they got sold a bad replacement / refurbished breaker.

The ATS will sense a loss of normal power (like this morning). And within a second will send a start signal to start the Genset. But I don’t believe the 1600 should have tripped. It should have remained in the closed position like I recall the previous breaker doing.

The building's built in generator is 275kw and supply’s 480 back into the ATS. From there it distributes to the emergency circuit of the building. The only motors fed from our built in generator are the 480v fire pump (only runs if needed) and jockey pump (only runs to keep riser pressures up). . 120volt fire panel and it’s monitoring devices and magnetic door holders. . The rest is all 277 lighting and exit signs

This Genset mentioned above is separate from the rental unit we currently have onsite for the chiller plant. Since the 1600 is having issues handling the load of the chiller plant, we’ve kept the rental onsite and wired the plant directly to that for daily run.

 

[Elect117]

The ATS will sense a loss of normal power (like this morning). And within a second will send a start signal to start the Genset. But I don’t believe the 1600 should have tripped. It should have remained in the closed position like I recall the previous breaker doing.

The building's built in generator is 275kw and supply’s 480 back into the ATS. From there it distributes to the emergency circuit of the building. The only motors fed from our built in generator are the 480v fire pump (only runs if needed) and jockey pump (only runs to keep riser pressures up). . 120volt fire panel and it’s monitoring devices and magnetic door holders. . The rest is all 277 lighting and exit signs

This Genset mentioned above is separate from the rental unit we currently have onsite for the chiller plant. Since the 1600 is having issues handling the load of the chiller plant, we’ve kept the rental onsite and wired the plant directly to that for daily run.

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.