Nuisance tripping

[barrydmi]

480 volt 3PH.600 amp type TJ G.E molded case circuit breaker with Microversa trip module, ground fault tripping capability. Trips now and again. 2 months may go by between tripping. No ground faults exist. At time of tripping, maybe 125 amps or less. Had breaker tested. Found to be in normal working order. 4 VFD's on line 1-10 horse power. G.E. tech says could be caused from harmonic build up on the line due to the non-linier loads, such as the VFD's. But 2 month's have gone by and it tripped again. Any help would be appreciated. Thank you. Barry.

 

[pierre]

Re: Nuisance tripping

We had a similar problem with the service tipping, all 400 workers in the building slightly pissed off

Pierre

 

[brian john]

Re: Nuisance tripping

Cannot verify the micro versa trip. But several manufactures had trouble with certain static trip OCPs that were lightly loaded tripping on GFI.

Static trip devices may test OK but still be defective. (Try explaining that to a customer that just paid lots to test a single CB and it still trips).

I would recommend contacting GE (GOOD LUCK) and I will check on the manufactures with the light load trips. Additionall a power monitor could assist.

Also check ground current or zero sequence current readings.

What is the setting of the OCP's (LFGI) LT ST GF INST?

 

[brian john]

Re: Nuisance tripping

GE micro versa trip did not have the light load trip problem.

It is either the load, net current, or faulty OCP device.

You can replace the OCP expensive but quick. This will narrow the causes.

Or utilize a power monitor, monitoring voltage, phase currents, neutral current and ground current.

Check for net currents, this will be a byproduct of the power monitor, but if you do not own a monitor do this FIRST.


And of course check the OCP seting's, I'd like to know what they are.


We have seen quite a few sites over the years with faulty equipment that would trip the GFI randomly. Had a multi compressor HVAC unit the 4th compressor was bad. This compressor would only try to start on VERY hot days late afternoon when the sun was hitting the building. Everyone thought it was a defective GF relay. but.............

 

[barrydmi]

Re: Nuisance tripping

Than you for your reply's Gentleman. Very good point's. The OPC device settings are set pretty high. If it is bad, I will have to get a warrenty refund from the company that tested it. Thank's again pierre, and brian john.