Ground fault on chiller starting

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kcooper

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The following info relates to a building main GFP tripping upon starting of centrifugal chillers (w/ hermetic motors?). This is the second site where I have seen this happen. One with new chillers, one with old. Any thoughts on why?

"The most recent troubleshooting yielded the following information. GFP meter indicates about 160 to 180 amps normally. Jim looked at the highest reading on the meter since the previous reset, and it was 490 amps. He zero'd it and old chiller #1 was started. The meter jumped to 500 amps for about a minute, then backed off to 250 or 260. Old chiller #1 was shut down, the meter zero'd again, and old chiller
#2 was started. The meter again jumped to around 500 amps for about a minute, then backed down to 250 or 260. With both of these units off, the reading returns to about 160 to 180 amps."
 
brian john

brian john

Senior Member
Location
Leesburg, VA
Re: Ground fault on chiller starting

What type of ground fault system Zero Sequence Ground Return, not manufacture?

What is the setting of the ground fault relay current and time?

We have had trouble with GFP pick-up when starting large motors or when energizing large dry type transformers. When trip GFP system have low current and time settings. This was with Zero Sequence GFP systems, I believe the problem is related to inrush currents that are not zero sequenced. I am not an engineer and make the above statement based upon experience.
 
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kcooper

Member
Re: Ground fault on chiller starting

My question doesn't relate to the ground fault system itself. It's doing it's job. It's the chillers that I'm concerned with. They appear to be creating sizeable ground currents for extended time periods on start-up and while running.
 
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