On Wed, 11 Jul 2012 14:48:14 -0500, Peabody
wrote:

Jeff Liebermann says...


http://www.digikey.com/product-detai...967-ND/1095291

Watch out for the contact material and switching speed.
The original is 12msec max operate and 8msec max
release. The first (and cheapest) one in the list is
8msec and 6msec respectively, which should be faster
than the original. However, the contacts are AgSnO2
which is better than AgCdO contacts of the original.

Well, that one is silver/nickel per the data sheet. The
AgSnO2 version would be RT423012, which DigiKey doesn't
stock.

AgNi looks OK for contact material.
http://www.gljg.com.cn/en/lvc_sn.html
It has a bit higher resistance than AgSnO2 and will
therefore run warmer if you load the relay to the
maximum. However, since the UPS is rated at 550VA at
115VAC, you're limited to about 5A max on the contacts
anyway. That should work.

But this one:
http://www.digikey.com/product-detai...012-ND/1427674
is silver/nickel with gold plating - per the datasheet.
Would that be worth a couple extra bucks?

It's a bit difficult to decode what the data sheet says
about the contact material. It sorta hints that there
are several different types of contact material, but
doesn't offer any part numbers to distinguish them.
Dunno.

If it's gold, I would suggest that it's a bad idea.
Gold plating is only for a "dry" load. It's primary
purpose is to provide low contact resistance in circuits
that do not carry any current. The slightest arc across
the contacts, the few millionths of gold plating instantly
disappears, leaving a rather miserable connection to the
intermediate nickel plating between the gold plating and
copper contacts.

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