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Continuous operation of a general purpose relay? (midwest.social)

submitted 1 year ago by [email protected] to c/[email protected]

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Hello, I have a circuit that will need to return connected hardware to a default state if power is lost. The hardware can handle continuous voltage, so I'm thinking a simple solution would be to use a battery to provide that fallback power source. To avoid draining the battery, I'd like to connect it through a relay on the normally open contact and energize the relay directly from the main power supply on my board.

Do I need to look for anything in particular to make sure the coil on the relay I choose can sustain constant voltage for potentially months at a time without damage? Or, is there another similarly low cost and simple solution you'd recommend?

The circuit runs on 12VDC from a [Mean Well IRM-10-12 (specification), and the relays I have on hand are OMRON G5LE-14-CF 12VDC (specification). I don't see anything on the relay documentation that specifies a maximum duty cycle.

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[–] [email protected] 1 points 1 year ago (1 children)

Would this be a good use case for an SSR?

[–] [email protected] 2 points 1 year ago

I was thinking about that, but if they are using 12VDC + light load a MOSFET would be more cost and space efficient, and probably more electrically efficient too. No real voltage drop, and just a few milliohms added to the load.

I mainly use SSRs to switch mains power, although it's true they can be used for other things too.