Chiller Breaker Settings 1

[DRWeig]

Friends,

I've walked up on a chiller with the following settings on its breaker:

Instantaneous pickup 6400A
Short-time pickup 4800A
Short time 0.3s
Earth pickup 640A
Earth time 0.3s

Here's the chiller data. Note it's a Y-Delta starter.

Motor LRA= 2616 A
Primary RLA = 473 A
Min circuit ampacity 601 A
Max overload protection + 1000 A

I am suggesting the following breaker settings:

Instantaneous pickup 3500A
Short-time pickup 1000A
Short time 0.5s
Earth pickup 1000A
Earth time 0.5s

Would you confirm that I'm close to the correct settings? Any other suggestions?


Best to you,

Goober Dave

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[waross]

This looks a little high on the earth fault. I would set the earth fault just high enough to avoid nuisance tripping. If you get an earth fault in the windings near the wye end of a winding, it can do a lot of damage to the iron before the current reaches 1000 Amps. I would tend to shorten the time also. There should not be any coordination issues with a breaker feeding a single machine. If the current and time settings are too great, you may create upstream coordination issues.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[DRWeig]

Thank you Bill.

Best to you,

Goober Dave

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