Are there any advantages of using a 480-208/120 transformer versus a 7200 or 12470 volt primary transformer??? We're looking at a couple of 150KVA type K and about six 200KVA 208/120v standard xfmr's. Wouldn't the 12.47KV primary xfmr deal with load changes better than the 480V xfmr? Also, we would be able to cut down on supply amperage and physical size of the package with 12.47KV vs. 480v, right? Any thoughts??
Generally medium voltage (7kV or 13kV) service is better than low voltage (480V) for voltage drop, capacity and reduced conductor size. You need to consider who will be servicing the transformer (on site personnel/electrician, a third party electrician or the utility. Clearance and construction requirements help delineate installation differences.
#8871 - 04/09/0211:55 AMRe: Low voltage transformer??? Why???
This will be in a refurb of a hotel showroom where the 480 is already existing. They keep on saying that they're strapped for supply already in this area. I was thinking we should pull a 12.47KV line to a distribution to deal with the 8-10 xfmrs we will need, but they want to keep the old 480V lines... Perhaps if it was 10,000A service...
#8872 - 04/09/0204:58 PMRe: Low voltage transformer??? Why???
Who will supply and maintain the transformer? With deregualtion in Texas the customer would. Have you investigated the cost of going from a 480 voltage insulation rating to 12.47 kv? It seems the utility company would like to supply at the higher voltage (especially if the customer owns the transformer)because the losses on their side of the meter would be less.
#8873 - 04/09/0206:36 PMRe: Low voltage transformer??? Why???
All of the equipment will be customer owned and serviced by onsite Engineering department. We're still trying to come up with load sheets because we're in the early planning stages... We know the dimming system will need 208/120 700KVA service
#8875 - 04/11/0210:02 PMRe: Low voltage transformer??? Why???