DC contactor [RE-wrenches]

[R. Sparks Scott]

	Kurt;

	You do have some options here, but a few questions first:

	1) Do you want/need the full 60 amp pass through on the Trace? If the grid
intertie and battery charge current is all that you need to handle on the
AC1 input, you could breaker it for something like 20 amps and use a
smaller relay. If you wanted the full current available, consider also
using AC2 in with a separate breaker in the event you needed to lay a heavy
charge on the batteries, etc. You didn't mention a generator. Obviously, if
this input is already used, it's not a option to use AC2.

	2) Do you have to switch the neutral along with the hot leg? My system has
the neutral running straight to the neutral buss inside the Trace. Don't
know the code on that. You'd get by with one less set of contacts.

	I looked in the Grainger catalog, and the only thing available in a 60 amp
current range is mercury relays, and they are all 120/240 volt coils. You
could use one of these with another 24 volt relay to switch the 120 volt
coil voltage... not elegant, but it would work.
	If I had to have the full current, I'd probably go for a solid-state relay
set-up. Newark Electronics has a large selection, some of them are "double
pole", and operate on DC control voltages from 3 to 48 VDC. They feature
quite a few that will handle 75 amps RMS and 1000 amps surge. Let me know
if you want to know more about this, I'll comb the catalog more carefully
to get you some part #'s and $'s. The solid state relays have
zero-crossover switching, no arcs. In larger current systems, they may need
an inexpensive heat sink to stay cool.

	-S

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