What kind of fans? And are they large? On the far end of the 1300’ run? Sounds like hat 1300’ foot run is acting like an inductive whip to the radians. I suggest installing ferrite cores on the dc and ac conductor pairs to attenuate transient spikes.
Maverick Brown Off-Grid Solar Commander since 2006 Maverick Solar Enterprises, Inc. • Solar Commander Remote Power • SunFlow Systems Cathodic Protection maver...@mavericksolar.com 512-460-9825 > On Jan 26, 2022, at 1:29 AM, Nick A Lucchese <luccheseso...@me.com> wrote: > > Hello again Wrenches, > > While the failed controller topic is fresh I want to ask opinions/advice on > arc faults. I know quite well that they can be mysterious so not sure I’ll > really get anywhere but here goes. This particular off grid system consists > of two Radians, 2 GSLC’s, FNDC, a 25.2 KW array and 6 FM80’s. 4.2 KW STC into > each controller which I now know is over their new recommended max wattage > after they changed the spec sheets on us a couple years ago without renaming > it an FM70. The system has been in for over 5 years now but from the > beginning I’ve had a large amount of failures with the FM80’s failing and > registering a dead short on the PV input side of the controller. Not > exclusive to any one of the six arrays and I’ve definitely gone through to > torque and tighten all of the connections. I’ve tried other controllers > throughout my troubleshooting and concluded it’s arc faults for a few > reasons. Mainly, as long as I have a Midnite Classic installed with the other > 5 FM80’s it will absorb the arc fault and just go to it’s temporary state of > displaying an arc fault and after I reset it everything starts back up and > operates normally. Survives the incident without failure unlike the FM80 and > at the same time protects all the other FM80’s. When the site goes back to > FM80’s exclusively the failures are inevitably more frequent. I’ve also > installed a Magnum PT100 for awhile to see if it would fail too but it > survived for over a year before I terminated that particular test. > > Luckily, one of the times I was there when an FM80 failed so I was able to > see that it coincided with some fans (obviously on the AC side) that had > kicked on when I observed usage on his Egauge (system has Blue Ion 2.0’s and > HI's). I have also been able to determine it’s likely some fans because the > long durations without failures also coincide with long periods without the > fans although failures are still happening sometimes and he says he’s changed > up his fans. The Egauge has been a very useful tool for various reasons but > unfortunately I can’t pinpoint when the units fail since they often go > unnoticed until I am at the site or notice low PV production on Opticsre. I > just happen to get lucky the one time I was there to correlate the exact > moment with the fans. > > One major detail that makes this site different is that after my initial > install work he had some other yahoos in to pull the feeders to power his > other subpanel some 1300’ feet away. Unfortunately they did so without > pulling an equipment ground along with the power conductors so the two sides > do not share a common ground. This is the most major deviation from any of > the other systems I’m responsible for and this is the only site I have > frequent high rates of unwarranted controller failures. I’m uncertain if the > failures are due to AC ripples/transients from the extremely long run, lack > of common ground or perhaps one particular appliance. My preferred solution > in the process of elimination is fixing the lack of common ground by > re-pulling all the conductors with an EGC but that would not only be > expensive but quite difficult as he just informed me the other day that there > are no pull boxes in between the two destinations. I wish I could just walk > away from any responsibility since their foolish decision not to pull the EGC > originally was not a mistake of mine but I really need to help him resolve > this since replacing the FM80’s so often is obviously expensive as well as > time consuming. Obviously it would be extremely frustrating and defeating if > he were to go to all the effort of pulling the new ground and the failures > still occur. > > I thought about replacing the 6 FM80’s with 4 FM100’s but that would require > a profound amount of work by the time I change up the array strings and > OCPD’s plus I’d have to re-imagine placement due to the physical differences. > To avoid nuisance tripping, I already have the Midnite 100 amp GFP assemblies > in place and am adding two more Radians with GSLC’s so feasibly would have > the accommodations as far as space for OCPD’s are concerned. We do plan on > expanding his arrays soon so at some point I will have to address this known > snag of mixing FM80’s and 100’s in the same system as recently discussed on > the list. Thinking I might try this mix approach on my own house for awhile > but not rushing to deploy at any client sites. > > Any ideas? Suck it up and have him pull a ground 1300’ at today’s copper > prices? I’ve got Midnite SPD’s on all the arrays as well as the AC side but > perhaps there’s some other sort of additional surge suppressor or something I > can install to suppress arc faults originating on the AC side? WWWMD (what > would William Miller do)? Only half joking here, I often find myself asking > that when I encounter some sort of unusual solution required to balance > something out of the ordinary and William’s procedures have impressed me for > decades. No offense to the rest of you pro’s though, his meticulous > documentation and notes just appear levels beyond (especially speaking for > myself)! > > Off to work, enjoy your day, Nick > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org >
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