[Amps] SSR snubbers

[John Lyles]

I cannot find info on the snubbers we used at BE Inc. on the transmitters, to keep the chatter from occuring in the SSRs when inductive loads switched in the system on the same power line and caused them to false on. Looking at their current design (8 years old) they replaced all the SSRs with homemade devices they called OCRs, for Optically controlled relays. Apparently someone didn't like the use of commercial SSRs or they had a lot of trouble with them, as the new units appear to fit the same mounting screws. They have a real relay on the output, and still have a 0.03 uF and 560 ohm 1/2 watt R for snubber. This is actually for relay contact lifetime. And they are only used to switch the primary power to the coils on large AC contactors that switch the real power to transformers and fans. The capacitor pass the high frequency components of transients while the resistors dissipate it. You find it in most of the old databooks for SCRs and TRIACs as Paul suggested. If you make the C
too large, you suffer excess AC leakage current, and there is an empirical or prescribed way of figuring it, i just cannot remember 20 years. But others here apparently haven't seen the effects using SSRs. I would definitely not depend on them for safety, nor would I depend on contactors or relays for that matter. Pull the plug. 
73
John
K5PRO