Ground Fault Protection Nuisance Tripping:
I am trying to determine the cause of the nuisance tripping on a GE 2000A/3P, 4-wire fusible switch feeder with an integral GFP. This feeder feeds a 2000A, 480/277V, 3ph, 4w distribution board that supplies power to (4) chillers and a bunch of pumps and misc. motor loads. Chillers 1,2,&3 are each rated at 261FLA, and chiller 4 is at 290FLA. The net total connected load on the distribution board is about 1600A. The GFP is currently set at the max. setting (1100A trip, max. time delay). When all 3-chillers, pumps and assoc. motor loads are on line, the GFP works OK. But the moment chiller #4 is put on line, the GFP trips instantly, shutting down the whole feeder distribution. The electrician tried to isolate or disable the GFP by removing the fuse block that feeds the GFP control circuit. Again, the GFP trips when the fourth chiller was put on line. I suspect that the GFP is defective, or there is improper connections (polarity). It seems that the GFP is reading the feeder 3-phase load current as imbalance and interpreting the error signal a a fault situation. Any ideas or recommendations on how to fix this problem? Thanks very much!
I am trying to determine the cause of the nuisance tripping on a GE 2000A/3P, 4-wire fusible switch feeder with an integral GFP. This feeder feeds a 2000A, 480/277V, 3ph, 4w distribution board that supplies power to (4) chillers and a bunch of pumps and misc. motor loads. Chillers 1,2,&3 are each rated at 261FLA, and chiller 4 is at 290FLA. The net total connected load on the distribution board is about 1600A. The GFP is currently set at the max. setting (1100A trip, max. time delay). When all 3-chillers, pumps and assoc. motor loads are on line, the GFP works OK. But the moment chiller #4 is put on line, the GFP trips instantly, shutting down the whole feeder distribution. The electrician tried to isolate or disable the GFP by removing the fuse block that feeds the GFP control circuit. Again, the GFP trips when the fourth chiller was put on line. I suspect that the GFP is defective, or there is improper connections (polarity). It seems that the GFP is reading the feeder 3-phase load current as imbalance and interpreting the error signal a a fault situation. Any ideas or recommendations on how to fix this problem? Thanks very much!