[RE-wrenches] Efficient step up, down transformers

[Dana]

Seriously I have never heard of 99% eff. under load with a
transformer.  Anyone else heard of this kind of eff. factor?

 

Dana Orzel

Great Solar Works, Inc

E - dana at solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

 

"Responsible Technologies for Responsible People since 1988"

Do not ever believe anything, but seriously trust through
action.

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf
Of Mark Frye
Sent: Monday, July 25, 2011 9:11 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Efficient step up, down
transformers

 

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

 

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