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 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
>
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