1600amp Square D tripping

Relisys190 said:
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?
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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.
 
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 ?
 

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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.
 

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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.
 
jim dungar said:
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.
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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 ?
 
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.
 

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Relisys190 said:
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 ?
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That should be done by an engineer who has studied the system and the equipment.
 
Relisys190 said:
If the short time protection function is causing the trip should the breaker vendor recommend increasing the settings ?
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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.
 
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 ..
 
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.
 
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