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<font size=3>Lars:<br><br>
I have been dealing with the same issue for an on-grid scenario. We
were asked to bid a large installation to cover the idle losses of poorly
selected transformers. Before we bid the project, we first looked
at why the client's electric bills were so high. We found that
changing out his transformers would save him considerable power. We
are waiting for that to be accomplished and then we will bid on a smaller
system. Here is the scenario:<br><br>
The customer built a new straw bale home 2,000 feet from his meter.
The electrician ordered two large (75KVA), standard-wound transformers to
step up to 600 VAC and then down to 120/240. The customer's
electric bill went from ~$50/month to ~$200/month and he has yet to move
his laundry equipment into his new house.<br><br>
Turns out the transformers had a large idle loss. Using less
electricity did not help this customer. We had an electrical
engineer do an analysis. Answer: Changing the large
transformers to custom-wound 15KVA units would reduce the monthly bill
enough to pay-off in 5.4 years.<br><br>
Installing standard transformers in step-up / step-down configuration is
a mistake. Voltage drop and in-rush problems occur (I have
experienced the in-rush problems and they can be difficult to
resolve). I have attached a white paper that explains.<br><br>
Good luck,<br><br>
William Miller<br><br>
<br>
At 07:42 AM 7/25/2011, you wrote:<br><br>
<blockquote type=cite class=cite cite>Wrenches,<br>
I recently installed three “ultra -efficient” step up-down transformers
on an off grid micro grid project with a 1500’ wire run. The grid is
powered by a an old SW4024(120v) output, stepped up to 480v, and stepped
down to 240v at two locations. I was told by the manufacturer that they
were “99% efficient under a full load”, but upon firing up the system, I
found a NO LOAD AMPEREAGE OF 15.6 amps!!! Needless to say, a completely
unworkable situation for an off grid scenario, as the 840ah battery would
be drained in a couple of hours before anything was turned on. I’m
wondering if anyone out there has either found off grid friendly step
up-down transformers, or if I’m just screwed and need to pull parallel
4/0 runs (probably the price of a new car) to fix the problem.
HELP!<br>
<br>
<b><i>Lars Ortegren<br>
</i></b> </blockquote>
<x-sigsep><p></x-sigsep>
William Miller <br>
Miller Solar<br>
Voice :805-438-5600<br>
email: william@millersolar.com<br>
<a href="http://millersolar.com/" eudora="autourl">http://millersolar.com<br>
</a>License No. C-10-773985<br>
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