Transfer Switch

MEXICOWANDERER wrote:


Brulaz señor please check the imprinted label on the relay that hums. You received a DIRECT CURRENT (DC) 110 vdc relay. Whether by mistake or intention I cannot tell you.

These relays operate SILENTLY - period. And they do not heat up via the magnetic coil. I have purchased 100+ of these relays in 40+ years so my answer here is not guesswork. The Miss Kelley 2, or example has eighteen of these relays. By their accident they had 33 amperes passing through the NC contacts on the Bridge relay and I found the issue by accident they were running a pair of AC heaters off the same receptacle.

Now REVERSE the problem. Install a 120 volt AC relay in a 110 volt DC circuit. The relay will chatter badly. The magnetics lose about 30% if misapplied.

EDIT EDIT EDIT EDIT EDIT EDIT

I just now ran across this excellent piece in PDF format explaining this more in detail...

http://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=13C3250_AppNote&DocType=CS&DocLang=EN

Thanks for that info. It's possible I ended up with a DC coil.

The NTE RO4 relays are available in both DC and AC with a single letter in their model designation (D or A) separating them, and 110VDC vs 120VAC. Can't get to the trailer right now but will take a look when we get back.