After 100's of thousands of inverters having been shipped in the last
many years
and thousands of inverters broken and shorting the battery terminals,
there has
never been (to our knowledge) one breaker that has not tripped.
The Midnite site lists the AIC rating of all our breakers I believe.
The Carling F series of Magnetic-Hydraulic breakers poop sheet is here...
http://www.carlingtech.com/sites/default/files/documents/F-Series_Details_%26_COS_0.pdf
I guess there isn't a graph of AIC vs. voltage on their F series web
page but we remember
them showing us figures or a graph that says those breakers have an AIC
of more than
100,000 amps at 48 volts. We'll try to find that info or you may be
able to get that
from Carling.
I have, many times, directly connected these breakers across good L-16
battery strings
to demonstrate the left-hand rule to people where the 4/0 cable jumps
apart or towards each
other when very high current passes through those wires when they are
near each other.
It always trips. Never tried it at anything above a 48V battery banks IIRC.
Robin would like to mention that anyone that wants to use T-Classc
fuses.... Welcome back to the 1990's
boB
On 4/9/2013 1:23 PM, Ray Walters wrote:
Hey Bob;
Can you share that AIC vs Voltage chart?
Thanks,
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 4/9/2013 1:46 PM, boB wrote:
Those 250 amp and 175 amp breakers we have used for many many years now
have an AIC of 50,000 amps at 125 volts and if you look at the curve,
at 48 volts
they are around 100,000 amps. I think that this information is on
the label
of the breaker.
How many problems have you had with the Carlings or any other type of
those large breakers ?
boB
On 4/9/2013 10:40 AM, Michael Welch wrote:
If anyone would like an Acrobat version of this article, you can
find it here:
ftp://ftp.re-wrenches.org/pub/hp27_pg26_freitas.pdf
<ftp://ftp.re-wrenches.org/pub/hp27_pg26_freitas.pdf>William Dorsett
wrote at 07:00 AM 4/9/2013:
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 /Overcurrent Protection for Battery-Powered Systems
/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.
175A ITE breaker with 42,000 AIC "simply tripped...but still
allowed a peak current of 2960 amps
200A Class T Littlefuse "opened promptly with no external signs of
stress...1920 amps peak current"
Christopher's recommendations:
"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.
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.
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.
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."
It won't pull up anymore on HP's article search but probably
Michael has a copy he could post for those interested./
/
Bill Dorsett
_______________________________________________
List sponsored by Home Power magazine
List Address:RE-wrenches@lists.re-wrenches.org
Change email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive:http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Change email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Change email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
