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After 100's of thousands of inverters having been shipped in the
last many years<br>
and thousands of inverters broken and shorting the battery
terminals, there has<br>
never been (to our knowledge) one breaker that has not tripped.<br>
<br>
The Midnite site lists the AIC rating of all our breakers I
believe.<br>
<br>
The Carling F series of Magnetic-Hydraulic breakers poop sheet is
here...<br>
<br>
<a class="moz-txt-link-freetext" href="http://www.carlingtech.com/sites/default/files/documents/F-Series_Details_%26_COS_0.pdf">http://www.carlingtech.com/sites/default/files/documents/F-Series_Details_%26_COS_0.pdf</a><br>
<br>
I guess there isn't a graph of AIC vs. voltage on their F series
web page but we remember<br>
them showing us figures or a graph that says those breakers have
an AIC of more than<br>
100,000 amps at 48 volts. We'll try to find that info or you may
be able to get that<br>
from Carling.<br>
<br>
I have, many times, directly connected these breakers across good
L-16 battery strings<br>
to demonstrate the left-hand rule to people where the 4/0 cable
jumps apart or towards each<br>
other when very high current passes through those wires when they
are near each other.<br>
<br>
It always trips. Never tried it at anything above a 48V battery
banks IIRC.<br>
<br>
Robin would like to mention that anyone that wants to use T-Classc
fuses.... Welcome back to the 1990's<br>
<br>
boB<br>
<br>
<br>
On 4/9/2013 1:23 PM, Ray Walters wrote:<br>
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<blockquote cite="mid:516478A6.80809@solarray.com" type="cite">
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<div class="moz-cite-prefix">Hey Bob;<br>
<br>
Can you share that AIC vs Voltage chart?<br>
<br>
Thanks,<br>
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760</pre>
On 4/9/2013 1:46 PM, boB wrote:<br>
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<blockquote cite="mid:5164702D.2060909@midnitesolar.com"
type="cite">
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Those 250 amp and 175 amp breakers we have used for many many
years now<br>
have an AIC of 50,000 amps at 125 volts and if you look at the
curve, at 48 volts<br>
they are around 100,000 amps. I think that this information
is on the label<br>
of the breaker.<br>
<br>
How many problems have you had with the Carlings or any other
type of<br>
those large breakers ?<br>
<br>
boB<br>
<br>
<br>
On 4/9/2013 10:40 AM, Michael Welch wrote:<br>
</div>
<blockquote
cite="mid:946180.52584.bm@smtp107.sbc.mail.ne1.yahoo.com"
type="cite"> If anyone would like an Acrobat version of this
article, you can find it here:<br>
<br>
<a moz-do-not-send="true"
href="ftp://ftp.re-wrenches.org/pub/hp27_pg26_freitas.pdf"
eudora="autourl">
ftp://ftp.re-wrenches.org/pub/hp27_pg26_freitas.pdf<br>
<br>
</a>William Dorsett wrote at 07:00 AM 4/9/2013:<br>
<br>
<blockquote type="cite" class="cite" cite="">This topic comes
up often enough that we ought to mention a yellowed article
in Home Power, (1992 Issue 27, pg 26). Christopher Freitas
wrote <i>Overcurrent Protection for Battery-Powered Systems
</i>where he describes experiments he did back when he was
with Ananda. He put a 2000 A Big Switch to initiate a short
(4/0 cable) between the terminals on a set of four golf cart
batteries (2 strings @ 12V). In series, he put in a 500A
Shunt so he could measure current passing and various fuses
and breakers. “For comparison, we decided to directly short
the battery…the meter read 6960 amps peak current (three
seconds) …during each test the 4/0 cable lifted off the
ground 4 inches into the air by the forces generated by the
extremely high current..” They videoed the 250 A ANN buss
fuses arc and smoke; the 200A Heinemann Series AM breakers
(paralleled ones that maybe Roy mentioned) went 3 seconds
without breaking and the video showed a flash and blue
smoke. <br>
175A ITE breaker with 42,000 AIC “simply tripped…but still
allowed a peak current of 2960 amps<br>
200A Class T Littlefuse “opened promptly with no external
signs of stress…1920 amps peak current”<br>
Christopher’s recommendations: <br>
“Every AE system must have overcurrent protection able to
interrupt the maximum current available from the batteries.
For most systems, the main protection should use current
limiting high AIC fuses, such as a Class T or Class R. A
disconnect switch which allows the fuse to be safely changed
should be included. A lower cost alternative is to mount the
fuse in a fuse holder without a disconnect. Although the
fuse would always be electrically hot, it normally would
not be changed during the life of the system. The fuse
holder should be mounted outside the battery enclosure.
Fuses should not be bolted directly onto the battery
terminal, as they are not designed to handle the physical
stresses that can occur without the protection of a fuse
holder.<br>
<br>
Fuses which have exposed elements, such as ANN fuses, should
not be used because they are not current limiting and have
only 2500 amps AIC. They also may be a significant hazard
when installed near batteries. <br>
<br>
High AIC breakers, like the Heinemann Series CF (25,000 Amps
AIC @ 65VDC) can provide overcurrent protection for
individual items. They cannot be used to protect lower AIC
breakers. This eliminates their use as a main disconnect in
most systems. <br>
<br>
Low AIC breakers, like the Heinemann Series AM (5000A AIC
@65 VDC) or the Square-D QO (5000A @ 125 VDC) can be used in
load distribution centers and components, but must be
protected by a current limiting fuse. Using low-AIC breakers
alone will not provide sufficient protection with a battery
system and may be a significant hazard during short circuit
situations.”<br>
<br>
It won’t pull up anymore on HP’s article search but probably
Michael has a copy he could post for those interested.<i> <br>
</i> <br>
Bill Dorsett</blockquote>
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