Anti-Islanding Re-certification and CYA [RE-wrenches]

[Bill Brooks]

Travis,

This is not a new issue. We have been 'round and 'round with utilities on
this one. Utilities routinely test relays because historically they were
analogue devices that tended to drift in their settings over time. Most new
equipment now is digital. They still do periodic testing, but their test
intervals are significantly longer than for older equipment.

Islanding capabilities are programmed in software so it either works or it
doesn't. Voltage settings of an inverter are the most likely to drift if a
sensor starts to drift, but at some point it will cause the inverter to shut
down since the voltage has to be in a defined window just to run. Periodic
testing can be very expensive or it can be easy, depending on the
requirements of the test and how readily testable the inverter is. I would
like to see self-test features built into every inverter so that the system
owner can push a button, similar to a GFCI, and the unit will test whether
everything is operating properly.

Not many people test their GFCIs like they should, but it doesn't cost
anything either to test. It does have to be built into the unit, however, so
redesign can be expensive for the manufacturer.

Bill.


-----Original Message-----
From: Travis Creswell, Ozark Solar [mailto:ozsolar at ipa.net]
Sent: Wednesday, October 23, 2002 9:54 PM
To: RE-wrenches
Subject: Anti-Islanding Re-certification and CYA [RE-wrenches]


My local utility engineer called me today and asked me a very interesting
question that he thought of after a recent "event".   I believe the "event"
****snip****

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