I've asked before on this topic without an answer - maybe lucky this time.
What's the failure mode for SSRs? Do they fail short circuit or open?
Working on the basis that 'Murphy rules - OK?', I've always assumed that the
failure mode is short circuit, and then figured that mechanical relays can at
least be seen to be stuck closed (well, sometimes) and gone for those. Plus a
neon indicator across the bottom electrolytic of the HV stack, a circuit breaker
on the AC feed so the amp can be totally isolated, and final line of defence, a
shorting stick. Even so, I never feel happy about touching the HV lines after
all that....but if the SSR fails short, it could be inconvenient at best.
Any answers from the guys who've used them?
And for Larry's benefit, he's not the only one to have made mistakes - except,
funnily enough, my worst shocks have all been at work. As a result, I don't
like 'live' neutralising! The big danger I find is in working on a tube or
hybrid transceiver - I'm so used to very low voltage that I forget that you can
have 300 volts or more floating around inside.
73
Peter G3RZP
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