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Siemens QO breakers DC rating?
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Breakers make a handy switch for when you need to reboot the charge controller, but in real world, your 8A panels can't trip a 10A breaker, except for a Edge of Cloud lensing event. -
Originally posted by Sunking View PostDead serious, I am a professional electrical engineer with 40 years of experience. A solar panel is a Current Source, not a voltage source. With one or two strings of panels, makes it impossible for a solar panel system to operate a fuse. A 250 watt panel with a dead bolt fault will only deliver roughly 8 to 10-amps of current. 8 to 10 amps of current on a 15 or 20 amps breaker or fuse is a normal load current and will never operate a fuse.That is why electrical codes do not require a fuse on solar panels unless you cross the line with 3 or more strings.
Look at any panel specification and look for the spec Isc and learn what it means. Isc = Current Short Circuit. A 200 watt panel Isc = roughly 8 to 10 amps. That is the absolute maximum current that panel can deliver with its output shorted out (two output wires twisted together tightly.) Please explain how 8 to 10 amps is going to operate a 15 or 20 amp fuse or breaker.
You can certainly use OCPD on the panels if you wish, but they are not required and an unnecessary expense.
Last edited by PNW_Steve; 11-12-2020, 11:58 PM.Leave a comment:
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Originally posted by PNW_Steve View PostApparently there are few to none when it comes "right designs". We use overcurrent protection on every circuit.
Look at any panel specification and look for the spec Isc and learn what it means. Isc = Current Short Circuit. A 200 watt panel Isc = roughly 8 to 10 amps. That is the absolute maximum current that panel can deliver with its output shorted out (two output wires twisted together tightly.) Please explain how 8 to 10 amps is going to operate a 15 or 20 amp fuse or breaker.
You can certainly use OCPD on the panels if you wish, but they are not required and an unnecessary expense.Last edited by Sunking; 10-13-2020, 11:56 AM.Leave a comment:
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Originally posted by Sunking View PostWhy do you think you need breakers? You do know with the right design, no breakers or fuses are needed. Guess you want to spend the cash huh?
Apparently there are few to none when it comes "right designs". We use overcurrent protection on every circuit.Leave a comment:
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Breakers are handy as a switch, for combiners to compare string performance as a quick sanity check. Also useful as a switch to disconnect PV from charge controller
Most fuse/holder combos are NOT rated for circuit interruption (meaning the contacts will fry if you pull a fuse while circuit is live) (only for the fuse to blow and interrupt)
And it's good practice to protect the cable from the battery to charge controller, in the odd chance the controller fails.
While sizing strings and only using 2 parallel PV strings, protection is not required, it's handyLeave a comment:
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Why do you think you need breakers? You do know with the right design, no breakers or fuses are needed. Guess you want to spend the cash huh?Leave a comment:
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My apologies, I somehow turned "Schneider" into "Siemens"
The breakers that I am looking for are actually Schneider.
Stuck on stupid......Leave a comment:
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Originally posted by PNW_Steve View Post
Doesn't look like they have them.
Thanks for trying.
You an also try https://www.solar-electric.com/marin...akers.html?p=2
Andy
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Originally posted by PNW_Steve View Post
Thanks.
Any clue where I can find the breakers I am looking for?Leave a comment:
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I don't know about the Siemens-QO
CARLING breakers rated for 150VDC
http://www.midnitesolar.com/pdfs/CA1...-767-321-L.pdf
Carling may make a Load Center version , these are bolt on.
The C-Series hydraulic/magnetic circuit breakers are
ideal for applications that require higher amperage and
voltage handling capability in a smaller package. They are
available in 1-6 poles, 0.02-100amps, UL Recognized up to
480VAC or 150VDC, UL489 Listed up to 240VAC or 125VDC,
with choice of time delays, terminal options, actuator
styles and colors.
Carling Technologies, Inc.
60 Johnson Avenue • Plainville, CT 06062-1177
Phone: (860) 793-9281 • Fax: (860) 793-9231
Email: sales@carlingtech.com • www.carlingtech.com
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Originally posted by Mike90250 View Posthere - the 150VDC rated from Midnight, not sure who makes them.
http://www.midnitesolar.com/productP...Order=13&act=p
Any clue where I can find the breakers I am looking for?Leave a comment:
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here - the 150VDC rated from Midnight, not sure who makes them.
http://www.midnitesolar.com/productP...Order=13&act=pLeave a comment:
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Originally posted by bob-n View PostI thought that QO was the Schneider SquareD breaker tradename. SquareD QO are only rated for 48VDC.
https://www.se.com/us/en/product-ran...egory-id=50310
The important thing to remember is that interrupting DC is much more demanding than interrupting AC. That's why these 240V AC breakers are only rated for 48V DC.
The Midnight Solar breakers are rated for 150VDC. Sounds like you need them.Leave a comment:
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I thought that QO was the Schneider SquareD breaker tradename. SquareD QO are only rated for 48VDC.
https://www.se.com/us/en/product-ran...egory-id=50310
The important thing to remember is that interrupting DC is much more demanding than interrupting AC. That's why these 240V AC breakers are only rated for 48V DC.
The Midnight Solar breakers are rated for 150VDC. Sounds like you need them.Leave a comment:
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