Thank you all for your suggestions, support and shared experiences. I have no resolution at the moment, but will plan to update everyone with what I find out. Moving forward, I am planning to look into noise on the AC side, as well as continue to look for patterns in terms of days, time, and conditions for the faults.
I know that the inverters have fairly recent firmware (2.62.30R) but SMA is soon to push new firmware to their -22 inverters. I already have the update and can install it next time I am there. It will be interesting to see if new firmware will have any effect. Cheers, Dave *--* *Dave Tedeyan* *Project Engineer* *Taitem Engineering, PC* 109 S. Albany Street, Ithaca, NY 14850 Voice: (607) 277-1118 x121 www.taitem.com On Tue, Nov 15, 2016 at 10:40 AM, August Goers <aug...@luminalt.com> wrote: > Dave, > > > > It is particularly interesting that you have two inverters with > intermittent arc faults. I’ve been following this thread, and agree that > looking for noise on the AC side makes sense. Definitely update firmware > too! > > > > That said, I thought I’d share a recent arc-fault story to this list. We > had a very persistent arc fault occur about a year ago. We replaced the > inverter, checked all DC-side wiring over and over, and could not find > anything. The arc fault intermittently persisted. The client had a big > fountain pump so we thought maybe that was the culprit. After a couple of > months of troubleshooting we disabled arc fault detection and everything > ran fine for about a year or so. Then, the client called us up and decided > to expand his system. We added a few panels to the roof and rewired all the > DC strings. During this process one of our installers found a melted MC4 > connector: > > > > https://goo.gl/photos/SR2ApXmoPcRcLZQu8 > > > > So, it turns out that we had a real arc fault after all! We had checked > the MC4 connections over a year ago and did not find this connector > assembly issue – apparently the terminal wasn’t fully seated into the > connector. In all fairness, it would not be easy to see whether the > connector was seated properly if the arcing wasn’t bad enough to show signs > of wear. We are giving our crews regular safety talks and training on all > sorts of splices and proper MC4 assembly methods to avoid arc-faults and > loose connection issues. It takes a lot of persistence. > > > > August > > > > *From:* RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] *On > Behalf Of *Dave Tedeyan > *Sent:* Thursday, November 10, 2016 10:14 AM > *To:* RE-wrenches > *Subject:* [RE-wrenches] SMA Arc-Fault > > > > Hi All, > > > > Maybe someone will have some ideas for why a couple inverters keep arc > faulting: > > > > -There are two SB7000TL-22 inverters, Sunpower branded. > > -3 Strings of 7 SPR-327's to each inverter. Kept separate until the > inverter. > > -Ground mount about 50' from the shed where the inverters are located > (indoors) > > -Simple grid connected system, no batteries. > > -There is a whole house generator co-located in the shed. > > -We interconnect by using piercing taps on the line side of the generator > transfer switch > > -There has been only one power outage there since the system was installed > in April, but the generator fires up weekly. > > > > -The arc faults have been happening on both inverters. Sometimes only one > at a time, sometimes both will go within a day of each other. > > -The events have been approximately one a month, but sometimes more, > sometimes less. > > > > -We have already checked every single connection in the system twice, by > two different people. > > -We have replaced the underground wires (and they looked just fine) > > -We have replaced all home runs. > > -We have replaced both inverters. > > -Arc faults are still happening. > > -Arc faults are not always on the same day/time of the week. > > > > I am wondering if this can be caused by the generator? > > Has anyone run into a situation like this or something similar? > > > > Thanks for your help, > > Dave > > > > *--* > > > > *Dave Tedeyan* > > *Project Engineer* > > > > *Taitem Engineering, PC* > > 109 S. Albany Street, Ithaca, NY 14850 > > Voice: (607) 277-1118 x121 > > www.taitem.com > > _______________________________________________ > List sponsored by Redwood Alliance > > 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 > > List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches. > org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > >
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