Hi Dick,
Thanks for the suggestion. I will run the concept by the SMA tech
people. I did use the SMA spec sheets in sizing the wiring, but
maybe opening the relays creates fault current at a voltage that will
jump the gap.
Drake
At 10:50 PM 6/4/2009, you wrote:
Hi Drake,
I'm sending you some attachments off list as well.
They are Sunny Boy Specs from the SMA Installation Manuals,
which are more complete than those on the SMA data sheets.
Note, the Maximum Output Fault Current for the 3000 & 4000 is 30 amps,
while Maximum Overcurrent Protection is 30 Amps.
The Maximum Output Fault Current for the 7000 is 57.6 amps, the
Maximum Overcurrent Protection is 50 amps.
This might be your problem.
Upsizing the conductors and breakers for the 3000 and 7000 might be a fix.
SMA tech support could probably shed some light.
Dick
--- You wrote:
Hi Dick,
There are three inverters, all Sunny Boys, a 3000, 4000 and a
7000. The breakers are QO. The AC conductor sizes are #8 for the
7000, #10 for the 4000 and #12 for the 3000. The breakers are set
for the NEC ratings of the wire (40 A, 30 A and 20 A.).
I sent some information to you off the list with some attachments.
Drake
--- end of quote ---
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP Certified PV Installer TM
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Mobile - 740-856-9648
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