[Amps] Crydom relays

[John Lyles]

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.