[Amps] Crydom relays

[Paul Kraemer]

No, snubbers are still a very important part of industrial designs.
Also, at least in case of the solid state relays with ac control input it 
doesn't take much stray wiring capacitance coupling to power wiring to turn 
them on
Paul K0UYA
----- Original Message ----- 
From: "John Lyles" <jtml at losalamos.com>
To: <amps at contesting.com>
Sent: Thursday, January 29, 2009 12:19 AM
Subject: [Amps] Crydom relays


> When I first used these in a medium powered broadcast TX design, I used 
> them for everything except the plate contactor and step start relays. Had 
> a lot of problems with the ones on the filament and blower AC lines, as 
> they would occasionally turn-on or -off on line transients when the main 
> plate contactor switched. We solved this transient susceptability problem 
> by installing RC snubbers and MOV's across the line terminals, not the 
> control terminals. I saw this series RC snubber approach in one of the old 
> SSR app. manuals, might have been International Rectifiers notes. It was 
> there to prevent dV/dt on the line from causing falsing. We used the 
> snubbers on them for years, in production units. I would imagine that 
> these days, the SSRs are improved in their immunity to line noise.
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