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Hello Wrenches,<br><br>
We are working on a system with three Sunny Boy inverters that feed into
a system that is backed up by a generator. The inverters are
isolated from the generator by relays that open when the generator is in
the warm up stage, before connecting to the electrical
system. <br><br>
What is happening is that the breakers, that connect the inverters to the
grid, trip, . What is apparently happening is that an inductive
effect from the inverter's transformers is causing current rushs through
the breakers when the relays open. This only happens when the
generator is in exercise mode, when the grid is still up and the
inverters are operating. <br><br>
My theory is that it is much like the ignition system of an engine.
(For the example I'm using a system that still uses points). When
the points open, the voltage rises, because current will try to continue
flowing from an inductor. This raises the voltage to very high
levels. The resulting arc jumps the spark gap. <br><br>
I think that with the inverters, the high voltage causes a current surge
when the voltage reaches a potential where current will jump the gap in
the contactor. <br><br>
Has anyone experienced this? Have you found a good solution?
We could retrofit relays on the DC side, but this would not be
convenient. If we use DC relays, is there a downside to
that? Could we use the AC contactor to connect the inverter
output to a large capacitor to absorb the surge? Do we need faster
contactors with a bigger gap? Would the voltages hurt the
inverters? <br><br>
Thanks in advance, <br>
<x-sigsep><p></x-sigsep>
<font color="#0000FF">Drake Chamberlin<br>
Athens Electric<br>
OH License 44810<br>
CO License 3773<br>
NABCEP Certified PV Installer </font><font size=1 color="#0000FF">TM<br>
</font><font color="#0000FF">Office - 740-448-7328<br>
Mobile - 740-856-9648 </font></body>
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