DC-GFP/2 protection [RE-wrenches]

[Steve Willey, Backwoods Solar]

Agreeing with Nick, my collection of lightning damage also seems to indicate
induction pick-up in buried cables, is most often associated with a damaging
strike, and often the system is not properly grounded, through some surely
are well grounded. Usually an AC or DC branch to an out-building, or between
power system and any other distant source/load is judged the inlet point.

The owners often suggest turning off their breakers in electrical storms. Of
course that opens a far too small gap to assure anything, but may help a
little in the lower voltage range spikes. What was once done effectively for
industrial equipment, ham-shack antennas,  etc. is flip a DPDT knife switch
that takes the antenna or buried conductor OFF the equipment and then
connects it directly to ground instead. An extension of this that works in
the simplest owner participating systems has been to manually disconnect
known lightning source wires by using a high current plug and socket, so the
plug and cable can be tossed about 2 feet away from the socket and can even
be plugged into a grounded socket. THAT stops the problem, if someone is
home and makes the change at the appropriate times. But it also shuts down
some functions of the system for the duration of the storm. So: if we could
just automate that. Conventional lightning protection schemes so far (MOV,
oxide granules etc ) add a ground path containing some voltage drop,but do
not remove the vulnerable connections.
Steve Willey       steve at backwoodssolar.com
Backwoods Solar Electric Systems
----- Original Message -----
From: "Nick Houser" <offgrid at prcn.org>
To: <RE-wrenches at topica.com>
Sent: Saturday, August 24, 2002 1:07 PM
Subject: DC-GFP/2 protection [RE-wrenches]


> Todd and Rob, et all-----------This is such a critical issue--is there any
> way we can determine the bottom line and lay it to rest, or is it going to
> be just another unanswerable grounding conundrum? Most of the electronics
> damage around here (vicious lightning territory) seems to involve
induction
> in buried conductors.

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