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Topic: SSR AC-motor RC snubber circuit - What type of capacitor to use? (Read 1 time) previous topic - next topic

olof_n

Hi!

I am controlling a AC-motor with a SSR.

If I have understood correct I should use a RC snubber circuit to protect the SSR output?

What type of capacitors could I use? High voltage ceramic disc capacitors are expensive and the stores I usually buy from don't have any.

Is it ok to use Mylar capacitors in a RC snubber circuit?

/Olof


runaway_pancake

I wouldn't be so concerned with the sort (mylar, polyprop., ceramic, etc) as much as the rating - over-rate it.
Which sort would depend most on environmental factors.

It's not impossible, but I'd be surprised if your SSR didn't have this incorporated already.
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

olof_n

Thanks for the answer.

The SSR are one of the common cheap ones on Ebay.

One like this: http://www.ebay.com/itm/Solid-State-Relay-SSR-25DA-25A-3-32VDC-Output-24-380V-AC-Solid-State-Module-/130905531225?pt=LH_DefaultDomain_0&hash=item1e7a93e359

Do you think I can skip the RC snubber circuit?

One more question: If I would use a 0,1uf capacitor and a 100ohm resistor, would it work with a small 0,25W resistor or should I get a bigger one?
The motor is 230V/0.02A.

runaway_pancake

1W, 2W

Two 220? 1/2W in parallel = 110? 1W
Two 50? 1/2W in series = 100? 1W
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

olof_n

Good idé.
I have som 200R 0,5W resistors that I can wire in parallel.

Thanks again.

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