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Getting 47N trips when on generator but never on utility.

Getting 47N trips when on generator but never on utility.

Getting 47N trips when on generator but never on utility.

(OP)
Device BE3-47N. tripping when set for 10%, never trips when set for 15% DRANETZ reports 1% or less. Waveform has flat spot at at zero crossing. Two devices do exact same thing. I think Specifying engineer has too tight a value. Any ideas. Load is a data center and building mechanical. Happens on primary and alternate generator. New CATS.

RE: Getting 47N trips when on generator but never on utility.

47 is a negative sequence voltage relay, but I've not seen an 'N' designator before. Is this a conventional voltage-sensing relay?

What are you measuring with the Dranetz - voltage THD?

How well balanced is the load?

RE: Getting 47N trips when on generator but never on utility.

(OP)
I am not the lead guy. They are all saying that the Basler relay should not react to 8% THDV. I saw the scope, it had weird zero crossing shifts, a flat spot between positive and negative at 180 degrees. The rest was normal switching power supply,etc along the rest of the sinewave.. Years ago this caused me big problems. I was told zero crossing shift was a big problem. I can't find info I read once, pre-internet.

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