Disconnect requirements for auto-transformers
Disconnect requirements for auto-transformers
(OP)
I'm trying to determine if I need a local disconnect switch for input and output auto-transformers associated with a 1,000 kVA rotary UPS unit. Closed thread238-126704: Code reference for Transformer Disconnect? was informative but I'd like to know the code references from which EEJaime bases his comments.
My particulars: UPS system consists of 3 ea. 600V, 1,000kVA rotary units in parallel. Installing a 480V, 1,000kVA rotary UPS in parallel. Thus we will have a 1,250kVA input auto-transformer stepping down from 600V to 480V and another 1,000kVA auto-transformer on the output stepping the voltage back up to 600V. All input and output switchboards are in the same room, less than 50ft away, but not necessarily within sight. The transformers will be 6ft away from front of UPS. UPS unit has an input disconnect and an output contactor. I appreciate your comments and code references.
My particulars: UPS system consists of 3 ea. 600V, 1,000kVA rotary units in parallel. Installing a 480V, 1,000kVA rotary UPS in parallel. Thus we will have a 1,250kVA input auto-transformer stepping down from 600V to 480V and another 1,000kVA auto-transformer on the output stepping the voltage back up to 600V. All input and output switchboards are in the same room, less than 50ft away, but not necessarily within sight. The transformers will be 6ft away from front of UPS. UPS unit has an input disconnect and an output contactor. I appreciate your comments and code references.





