3? 480x120/280 transformer

[hurk27]

have a job that I'm in the process of bidding and I need some in put on which would be the best/least costly way to go.

I was call to do some cleaning up of some code violations at a high school on 2 irrigation pump systems and found many other problems.

First I'll post a link to a satellite image of the site and then explain what I found:

Image from above of high school athletic fields

You can zoom in or out.

First the green looking roof building (main maintenance building) at the entrance to the ball fields has a 800 amp 277/480 volt I-Line Square D distribution panel.
From this panel a 100 amp 480v single phase feeder runs across this building to a two space panel with a two pole (240 volt rated)

 

[bob]

Re: 3? 480x120/280 transformer

Hurk
I see nothing wrong with using 3 transformers. The 480 volts system will see this as a 3 phase load. I would caculate the voltage drop on the 480 volt system. You want to be sure the taps on the transformer can correct the VD so that you get the 240 volts you need. You did not list the loads so I assume you have arrived at the total.
I would suggest you include a means to provide 208 or 240 3 phase service if it is ever needed.

 

[hurk27]

Re: 3? 480x120/280 transformer

Bob Yes I did do a voltage drop on the 480 volt feeder and I show 2.8% with a 200 amp load @ 500' using 3/0 copper.
I have been hitting the Price index book today and I come to about $4k extra to set the 1? transformers at each load center thus also reducing voltage drop. In no way after doing the figures I could come even close to the overall 5% VD for the whole system it more like came out to 3.8%, so I'm looking good there.

Hey thanks for the responce.