Author Topic: retrofitting arc fault breakers  (Read 3443 times)

vtmaps

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retrofitting arc fault breakers
« on: January 10, 2012, 01:43:24 PM »
I have started a new thread, rather than elongate the below quoted GFP thread.
boB designed the only DC-GFP in existence that broke both the positive and negative PV legs and also shorted the PV array.
Why short the array?  Isn't it enough to just disconnect the PV+ and PV- wires? 
I can't remember exactly why we shorted the array now.  Seems there was a good reason though.
If that memory comes back, I will post that.  It's good for parallel arc faults though, I know that !
I have been trying to educate myself about arc faults and their breakers.  I found this page to be helpful:
http://www.renewableenergyworld.com/rea/news/article/2009/12/dc-arc-faults-and-pv-system-safety
boB, you're correct that shorting (crowbarring) a parallel arc fault is the correct thing to do, but as the above linked article explains, it will worsen a series arc fault. 
The more I think about it, the more I realize that the solution may be to locate the arc fault breaker out in the combiner box... wait! I just received a new issue of Home Power magazine and I notice that Midnite is about to produce an arc fault combiner box.  Good thinking you guys!

now for the question: my Outback system is on a stretched Midnite e-Panel, with a dangerous GFP device in the PV+.
My Midnite combiner box is 100 ft (120 ft of conductor each way) from the e-Panel.  If I want to deploy arc fault breakers, do I need to put them in the e-panel AND the combiner box?  What arc fault breakers should I use?  How far from a fault will an arc fault breaker work?  Can an arc fault breaker serve as an over current protection device?  Can the arc fault breakers serve as PV disconnects?  Inside the e-panel, do I keep the two 80 amp breakers in series and just short out the 0.5 amp breaker?  Bottom line: How do I retrofit my system to make it safe?  I am fortunate in having no code inspections in my jurisdiction, so I can do the right thing (assuming I know what the right thing is).
--vtMaps

Robin

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Re: retrofitting arc fault breakers
« Reply #1 on: January 16, 2012, 02:58:02 AM »
Unfortunately it is not going to be easy to retrofit an existing system to add arc fault. Eaton is working on something that may allow it though. If you have the MidNite Classic charge controller, you already have arc fault protection from series arcs. We are working on an arc fault combiner, but it is not a breaker that goes into the combiner. It is a bunch of circuit boards. They will not be able to be retrofitted into any existing combiner.
Sorry,
Robin
Robin Gudgel

vtmaps

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Re: retrofitting arc fault breakers
« Reply #2 on: July 11, 2014, 03:46:50 AM »
We are working on an arc fault combiner, but it is not a breaker that goes into the combiner. It is a bunch of circuit boards. They will not be able to be retrofitted into any existing combiner.

Any progress on the arc fault combiner?  Its been more than 2 years since you ran ads in Home Power announcing an arc fault combiner, but I can't find the product on your web site.

--vtMaps