On 05/03/2016 07:46 AM, andy pugh wrote: > On 3 May 2016 at 13:37, Gene Heskett <ghesk...@wdtv.com> wrote: >>> And does the "fail to turn off" problem description include not >>> turning off ever again, even when removed from the circuit and from >>> all power? >> Generally yes, its an avalanche mode failure that shorts the switching >> junction. > I am not 100% clear on the source of this dv/dt. Is it simply the > result of turning on the main contactor, with the SSR turned off, when > the mains supply is in a high part of the sine wave? > The mains wires have inductance. The SSRs should only turn off at zero current, so that SHOULD help. But, your SSRs BOTH failed! That is an indication something is wrong. Is this SSR setup between a transformer secondary and the rectifier? Or, are you using it direct off the mains? If there is a transformer, the leakage inductance could be playing a part.
Yes, I suppose flipping the mains contactor will give a huge dV/dt, practically unlimited. That's why an RC snubber across the SSR outputs would help even more than an MOV, which will only clip voltage peaks. Jon ------------------------------------------------------------------------------ Find and fix application performance issues faster with Applications Manager Applications Manager provides deep performance insights into multiple tiers of your business applications. It resolves application problems quickly and reduces your MTTR. Get your free trial! https://ad.doubleclick.net/ddm/clk/302982198;130105516;z _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
