Rebekah and Jerry,
If I'm understanding R's post below, at that particular install you
could kill the disco for the inverter and still have 12 kV at 1 amp
running around. Call me a worry-wort but that sounds like a _pretty
important blind spot_ for us mortals to be aware of. Maybe the fact
that it was a 5 MW installation would keep less experienced people from
getting hurt but I'd sure like to see some good sized placards mounted
on the front gate and at the disconnects, inverters etc. warning of the
risk present even with a locked out/tagged out disco.
Greatly appreciate you posting this Rebekah, I doubt I would have
thought of this otherwise.
Greg Egan
Remote Power Inc.
Hey Jerry,
If I remember correctly - it was about five years ago - it was a little
complicated because the utility was doing the witness test where they pull
one phase and leave the other two connected, then test that there is no
current on any phase (because the inverters should shut off when one phase
drops). So two phases were still fully connected to the utility power, and
there was current flowing on those conductors, not from the PV array but
induced from the higher voltage lines. The inverter did shut off, but the
utility was still measuring over 1A (at 12.47kV). I don't think we would
have noticed except that the utility was specifically looking for the lack
of current on the lines at that moment. I don't know what the high voltage
lines were, maybe 100 kV and not that far above the PV system lines?
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