On Fri, 30 Dec 2005 12:26:21 -0500, the renowned "Bob Chilcoat"
wrote:

I am building a new compressor from a salvaged C-H tank and other parts, the
99.99 5 hp pump from HF, and a new 5 hp, 1 ph motor. The new motor is too
much of a load for the pressure switch. I can get a contactor from Ebay,
but I can also get some 25-amp solid-state relays a lot cheaper. Anyone
have any thoughts on this option? The motor has built-in overload
protection, so that's not a strong consideration.

SSRs need a decent heatsink for that current (16A or so @240VAC). If
the SSR fails on (which they are wont to do) you'll be testing the
safety relief valve. I don't see a lot of advantage to using an SSR in
this application- the compressor is noisy anyhow and the life probably
won't be an issue. Sometimes they have trouble turning off with motor
loads- try to get the kind that is "back to back SCRs" rather than the
triac kind.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
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