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UPS contribution to system

UPS contribution to system

UPS contribution to system

(OP)
I am doing a short circuit and load flow study for a system. When I ran the ETAP software, I notoced UPS sytem can cause the voltage rise and it does little contribution to the system short circuit. is it right?

RE: UPS contribution to system

Does ETAP model a UPS?
I use SKM and it doesn't model a UPS, which is ok, because I get worst case results considering the bypass path.
A UPS output is limited during a fault to about 300%, so it transfers to bypass to help clear the downstream OCPD.

RE: UPS contribution to system

As mentioned, the response of a UPS to short circuit conditions depends on the UPS design and implementation.  Without some type of automatic bypass, the SC response is very limited.  The 300% figure mentioned above seems maybe optimistic.  

With a bypass, the SC response is basically the same as if the UPS was not there and the system was fed via the mains.  

RE: UPS contribution to system

The UPS cannot contribute to the system fault, other than the one in the system downstream of the UPS. This too is in a very limited way, as already explained by dpc above.

raghunath_n00@rediffmail.com

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