While I've got you all on a roll I'd like to pose a slightly different question. What if I cut the hard wired wye secondary and reconfiqure as delta (primary and secondary). Could I then run the transformer as 480 delta primary to 120 delta secondary? It seems like I get the full KVA rating...
waross,
Thanks, the neutral of my 480 incoming power is grounded. Should I still follow your recommendations?
I don't think NEC applies strictly to our laboratory setting. Any engineering principles behind NEC would, of course, apply.
Steve
I reconnected the transformer primary from delta to wye. This reduced the phase to phase voltage on the secondary from 208 to 120 volts. I just finished running some 120 volt 3 phase delta (Navy) equipment off of this and always had within 3% phase to phase voltage balance. I did not have the...
The navy uses 400 Hz and 60 Hz power. Both at nominal voltages of 440 and 115. 115 volt 3 phase delta 60 Hz is common, as is 115 volt 3 phase delta 400 Hz. Most of the 400 Hz I've seen came from electric motor generators or solid state frequency changers (vs 400 Hz engine generator or turbine...
davidbeach,
My ignorance is really starting to show. I thought "H0" and "primary neutral" were the same thing and were both referring to the center point of my primary Y setup. Same on the secondary for "X0" and "secondary neutral". If this is the case and X0 is grounded, what should I do with...
Thanks davidbeach, you posted while I was composing. Rephrasing your advice, I should connect the new primary neutral to the existing secondary neutral.
The X0 secondary neutral is currently grounded. Is this OK? It may even be hard wired this way. Will I generate any unexpected neutral...
Thanks, but nope I mean 120 volt 3 phase delta (I acturally get Y because the transformer secondary is hard wired this way). The navy uses a lot of it. I do get this as I described and the secondary phase-to-phase is 120 volts. Phase to neutral is 120/1.73 = 69 volts. But now I wonder about...
I frequently need 120 volt delta power. It's always temporary for about a week and loads very from 1 to 30 kW. I usually simulate this by re-wiring a 480 volt delta to 208Y/120 transformer so that the primary is Y with the neutral ungrounded. I end up with 69 volts to ground on my grounded Y...
I have 3 single phase 1KVA 480/240 volt primary to 240/120 volt secondary transformers that would be easy to use 480 delta to 120/208 wye. I also have a 75 KVA 3 phase transformer that works 480 delta to 120/208 wye.
Steve
Thanks. I have a 125 KVA 400 Hz motor generator that puts out 350 to 480 volts (adjustable) phase to phase wye. Below 300 volts the voltage regulation gets bad (accordaing to Kato). From skogsgurra it seems I'd have the same problem with my existing 60 Hz transformers. Most applications would...
Can I use a 60 Hz dry type transformer for 400 Hz power? What if I derate the transformers? What would happen?
We are a testing lab that typically sets up equipment for a week and monitors operation continuously.
