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Grounding standards in the EU, for UPS systems.

Grounding standards in the EU, for UPS systems.

Grounding standards in the EU, for UPS systems.

My question concerns grounding practice for large UPS systems in the EU. I am specifically concerned with a UPS system that is considered a seperatly derived source in all modes of UPS operation. To initiate a transfer to bypass, the UPS would be placed in internal bypass mode. The transfer to maintenance bypass will include interlocking between the maintenance bypass circuit breaker and the 4 pole output isolation circuit breaker.

The intention is to perform a make before break transfer with overlapping neutral as well. The overlap for the neutral would be of a short enough duration to prevent the upstream Ground Fault Circuit to trip due to the Neutral being temporially connected to Earth in two places.

The external Circuit Breakers are housed in a switch gear cabinet, but not necessarily in a secured location.

Two key questions:

1) Is the overlapping neutral acceptable?

2) Is feed back protection required?

If any of the group members can offer an opinion or point me in the direction of the relevant standards it would be much appreciated.



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