Parallel transformers operation and NEC
Parallel transformers operation and NEC
(OP)
NEC permits using transformers in parallel operation and switching as one unit. Is switching as one unit a mandatory? Does that mean I have to use a 6 pole switching application, or I don't have to do that if proper tagout procedure is used? This is for 480v, 300KVA XFMRs application. Does anyone have any experience with that?






RE: Parallel transformers operation and NEC
450.7 Parallel Operation. Transformers shall be permitted to be operated in parallel and switched as a unit, provided the overcurrent protection for each transformer meets the requirements of 450.3(A) for primary and secondary protective devices over 1000 volts, or 450.3(B) for primary and secondary protective devices 1000 volts or less.
In my opinion, you are not required to disconnect both transformers at the same time, but if you want to do so you have to comply with this article.
RE: Parallel transformers operation and NEC