[RE-wrenches] Efficient step up, down transformers

[Mark Frye]

Lars,
 
Scary stuff. I worked with a system similar to this and went with big wire.
 
The problem with xfrms is that you can either have low standby losses and
good efficency at load or vis-a-versa, but you can't really have both. 
 
Were the xfrms specifically wound for 120x480 conversion? If not, it is
possible that the coil taps are connected in a manner that is not efficient.
 
That being said, 15.6 A @ 120V sound like an awefully large number. Perhaps
you have a bad connection at one of your pull boxes.
 
I would be happy to stop by and take a look at the xfrm spec etc. with you.

Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 
(530) 401-8024 
 <http://www.berkeleysolar.com/> www.berkeleysolar.com  
 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of lars
Ortegren
Sent: Monday, July 25, 2011 7:43 AM
To: re-wrenches at lists.re-wrenches.org
Subject: [RE-wrenches] Efficient step up, down transformers



Wrenches,

                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!

 

Lars Ortegren

 

Director of Operations

California Solar Electric Company

10141 Evening Star Drive, Suite 6

Grass Valley, CA 95945

 

Phone : (530)274-3671

Fax: (530)274-7518

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20110725/d4b314ca/attachment-0003.html>