-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray
Walters
Sent: Sunday, May 16, 2010 6:31 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] AC breakers used in DC applications
My understanding was that the din mountable QOU breakers were rated to 125
vDC
: Sunday, May 16, 2010 6:14 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] AC breakers used in DC applications
Voltage is not the issue here, it is current, and battery fault currents can
be staggering - far more than one would ever encounter in a typical AC
system fed from a distribution
The QO breaker I saw fail was a disconnect switch for an Air
303. The run from the battery bank was substantial, and the wire was
number 10. At the time, I calculated the amperage available (I
-V/R) and the short circuit current available was not close to the
5000 amp AIC of the breaker
HI Drake
I don't know if this could apply to your situation, but I've seen the QO/QOU
fail from debris getting into the breaker itself.
Around here there are insects that deposit mud into small openings, like on
those breakers.
I've seen this cause the breakers to fail.
jay
peltz power
On May
I've also seen failures/ nuisance tripping due to loose connections at the
breaker. The heat then wreaks havoc on the breaker internals.
R. Walters
r...@solarray.com
Solar Engineer
On May 17, 2010, at 8:23 AM, jay peltz wrote:
HI Drake
I don't know if this could apply to your situation,
nominal.
Rebekah Hren
North Carolina
http://thecarbonfreehome.com/
--- On Sat, 5/15/10, Kurt Albershardt i...@es-ee.com wrote:
From: Kurt Albershardt i...@es-ee.com
Subject: Re: [RE-wrenches] AC breakers used in DC applications
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Voltage is not the issue here, it is current, and battery fault currents can be
staggering - far more than one would ever encounter in a typical AC system fed
from a distribution transformer. I have seen a 200A Class T fail to act on an
48V inverter fault which resulted in welding the metal
Small (QO or Airpax-type) breakers in a distribution bank should be front ended
with a suitable DC master breaker or fuse that has the capability to interrupt
the available fault current. Ideally, the series combination should be rated
but at a minimum, a coordination study should be
:
From: Kurt Albershardt i...@es-ee.com
Subject: Re: [RE-wrenches] AC breakers used in DC applications
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Date: Saturday, May 15, 2010, 12:59 AM
The Square-D catalogs are marginally clear on which breakers are listed for
DC and for what voltages
Kurt
Fascinating story and valuable information. This is the kind of real world
experience we need to draw on. Reality can change quickly under extreme
conditions and one's education is not complete without this understanding.
Thanks for this post.
William Miller
PS: You are fortunate
/15/10, Kurt Albershardt i...@es-ee.com wrote:
From: Kurt Albershardt i...@es-ee.com
Subject: Re: [RE-wrenches] AC breakers used in DC applications
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Date: Saturday, May 15, 2010, 12:59 AM
The Square-D catalogs are marginally clear on which breakers
...@es-ee.com wrote:
From: Kurt Albershardt i...@es-ee.com
Subject: Re: [RE-wrenches] AC breakers used in DC applications
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Date: Saturday, May 15, 2010, 12:59 AM
The Square-D catalogs are marginally clear on which breakers are listed for
DC
I did see a QO breaker fail to trip on a 24 volt DC system with only
battery voltage behind it. It burned a #12 wire completely in two.
The 48v is a max rating not a nominal rating.
So yes only good for 12 and 24v systems.
However with CBI breakers I don't understand why the need for QO for
.
Bill Loesch
Solar 1 - Saint Louis Solar
- Original Message -
From: Allan Sindelar
To: RE-wrenches
Sent: Thursday, May 13, 2010 9:22 PM
Subject: Re: [RE-wrenches] AC breakers used in DC applications
Wow, Michael, look at the monster you have created, Dr. Frankensolarbozo
/10, William Miller will...@millersolar.com wrote:
From: William Miller will...@millersolar.com
Subject: Re: [RE-wrenches] AC breakers used in DC applications
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Date: Thursday, May 13, 2010, 7:18 PM
Bill:
I thought the rule of thumb
Fellow Wrenches,
Some time ago, Windy Dankoff had a rule of thumb to substitute (conservatively)
an AC breaker for use in a DC application.
Is anybody's memory, or perhaps even the old dog himself; if he is listening,
better than mine?
TIA,
Bill Loesch
Solar 1 - Saint Louis Solar
314 631
Bill:
I thought the rule of thumb was: Don't do it.
William Miller
At 05:10 PM 5/13/2010, you wrote:
Fellow Wrenches,
Some time ago, Windy Dankoff had a rule of thumb to substitute
(conservatively) an AC breaker for use in a DC application.
Is anybody's memory, or perhaps even the old
wrote:
From: William Miller will...@millersolar.com
Subject: Re: [RE-wrenches] AC breakers used in DC applications
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Date: Thursday, May 13, 2010, 7:18 PM
Bill:
I thought the rule of thumb was: Don't do it.
William Miller
At 05:10 PM 5/13
Is this conversation what you were refering to? 7/22/01
Others offered caution to this approach, but clearly the subject was
switches, not breakers.
Allan at Positive Energy wrote:
2. ...
I am using float switches to control 48V mercury displacement relays
for these DC pumps. Can anyone suggest
Wow, Michael, look at the monster you have created, Dr.
Frankensolarbozo!
Yes, that's the thread. And I was about to post that Windy left today
for Costa Rica...just a trip, not a move.
William, there are certain perfectly appropriate applications - such as
a pressure switch controlling a DC
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