shawn73
Member
- Location
- Napoleon, Ohio
I have been arguing at work with some individuals about transformers. More specifically a 45 Kva 480V 3 phase Delta primary with a 3 Phase Delta 240/120 (With a center tap)secondary. A transformer was purchased to provide power to a 200 amp panel board providing primarily 120V power to assembly line equipment. From what I have read and been taught a Delta-Wye configured transformer would have been correct to use in this situation. I always thought that all Delta secondary transformers with the lighting tap could provide the 120V voltage we needed, but only at 5% of the name plate KVA . I was also told that the nameplate KVA needed to be de-rated by 30% in this situation. It seems that running an entire 200 amp panel off of this center tap would cause an unbalanced situation in the transformer. I am having a hard time convincing people of this because there is already another transformer of this style running a 200 amp panel. In my opinion just because it's working - doesn't make it right. Am I right or confused?? Would a tranformer of this style be wired to 2 separate panelboards? One to provide some lighting voltage (5%) and the other panelboard to provide 3 phase 220V? I appreciate any information that could support my argument or correct my thinking. Thank you!