UPS feed for Process Control Computers

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awfourni

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We are installing a 100 KVA ups in a paper mill, to feed process controls computers and instrumentation. The actual load on the ups is about 40 KVA. The contractor claims that #2 75 deg C. conductors are sufficient for the load. It appears this is supported by exhibit 220.5 in the 2005 NEC.
 
Re: UPS feed for Process Control Computers

I am sorry but what is the question here? The size of the cable feeding the equipment is based on the size of the OCPD, which you have not provided. One can only assume that would be a 100-amp breaker.
 
Re: UPS feed for Process Control Computers

Are you talking about #2 on the input of the UPS or the Output? The input will draw more load while the UPS charges the batteries.

Does the UPS installation manual show minimum wire sizes??

Is this 208 volts, 3 phase???

40KVA is 111 amps at 208v-3 phase. #2 is good for 115 amps. Your load would have to be balanced very well for #2 to work. The OCP would have to be 125 amps.

Steve
 
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