Hi Wrenches,
I have a bit of a puzzler that I’m trying to get sorted out. I’ve been
servicing a Grid-Tied Battery Backup system that’s about 17-18 years old. The
system comprises of 2-GVFX3648s in series, with 2-MX60(at least I think they
are 60s) CC’s. Each CC has 3 strings of 3 tied to it, and each string has a
15A in-line 600V fuse. The modules are I believe are like 230/240Watt 60 cell
modules (sorry I don’t have pictures/specifics). We replaced the flooded
batteries with AGMs about a year and a half ago.
The situation is one of the 15A string fuses keeps blowing. It’s now happened
3 times and its the same fuse every time. First we just replaced the fuse and
under the surge/lightning assumption. Fuse blew again. Then I thought I found
the culprit. The #6 PV output from the combiner to the PV input breaker for
the CC was a bit darkened and very warm to the touch when I replaced the fuse
the first time. So I though maybe it was a loose connection on that lug and
that caused everything to heat up and eventually blow the fuse. I cut and
stripped the wire back and cleaned the lug and re-seated the wire in the lug.
Fuse blew again within a few months time. I then checked the Junction box on
the roof where the USE-2 wire connects to THHN, and did a visual inspection of
all the wiring on the roof. All of the Jbox connections and everything on the
roof “looked” ok. I have also check all of the connections inside the Outback
DC load center, and they look ok. Fuse replaced 3rd time and then it blew
again.
Before I take all of the panels off the rack, check panels, re-check string
wiring on the roof, is there anything else I should be checking? Seems like
that warm wire in the Combiner box is telling me something but I can’t figure
out what...I believe this is a new problem in the last 2-3 years but we are not
100% sure when the problem first came up…
As always, thanks for your help/ suggestions!
Amos
Amos Post
Integrity Energy
W 802.763.7023
C 802.291.2188
ienergyVT.com <http://www.ienergyvt.com/>
Facebook <https://www.facebook.com/integrityenergyllp?ref=hl>
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