This going back into my fuzzy memory, but I was on a project where we
used a bunch of SSRs back in ~~ 1990 or thereabouts. My recollection is
that they used an LED internally. That may have just been the brand we
were using at the time.
bp
<part15sbs{at}gmail{dot}com>
On 6/5/2025 7:52 AM, Ken Hohhof wrote:
So if it’s a solid state relay, there’s probably a silicon controlled
rectifier or triac and no actual relay coil? The control voltage
probably goes through a resistor to the gate of an SCR.
I’m no expert, but I’m guessing they’re fine, especially if it’s been
working all this time. They may even have checked with the component
manufacturer and verified it will work with the higher voltage. The
30VDC spec might just be a UL thing.
Perhaps it’s like 1N400x series rectifier diodes. Do we really think
they manufacture or test them differently to get 50, 100, 200, 400
volt ratings? They’re probably all the same diodes just with
different markings.
If I were designing something for mass production, I wouldn’t do it.
I’ve certainly seen problems caused by designs that worked but the
components specs were inadequate. Like a manufacturer does a die
shrink on a logic chip and it gets faster and now there’s a race
condition. Or a different manufacturer with an equivalent part gets
substituted and now 48VDC is too much.
*From:*AF <[email protected]> *On Behalf Of *Adam Moffett
*Sent:* Thursday, June 5, 2025 7:59 AM
*To:* 'AnimalFarm Microwave Users Group' <[email protected]>
*Subject:* [AFMUG] SSR control circuit over voltage
I was looking at pictures of someone else’s enclosure (a camera
company). They have a router powered through a NO solid state relay
and they’re keeping the coil circuit energized continuously. The
specs on the relay say the control voltage is 10-30VDC, but these
folks have a 48V power supply.
I’m not sure how long it’s been in service (finding out today), but
I’m wondering if this is a time bomb. Is that relay going to fail?
What’s the likely mode of failure? One article I saw while googling
suggested the relay might get stuck on….not the worst thing, but it
would defeat the purpose if that’s what happens.
-Adam
Get Outlook for iOS <https://aka.ms/o0ukef>
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