Relay contacts for AC and DC

Discussion in 'General Electronics Chat' started by superway, Sep 26, 2011.

  1. superway

    Thread Starter Active Member

    Oct 19, 2009

    Please help me this question.
    I have a SSR relay 3-32 vdc input, the switching side is 25 AAC. Can I use this relay to apply for switching side DC current (about 20 ADC) instead of AC current?

    In general application, can we use one relay (for switching side) for AC or DC current and voltage?


  2. mik3

    Senior Member

    Feb 4, 2008
    An AC relay can be used to switch AC or DC, however, a DC can switch only DC.

    The AC is able to switch a DC current however at a lower capacity. I am not sure of the exact value but you can find it in the datasheet.
  3. AlexR

    Well-Known Member

    Jan 16, 2008
    He is talking about a solid state rely, not a conventional relay with coil and contacts!

    I've never tried it but my guess is that it won't work. The AC SSR is usually just an opto-coupler and a triac in one package so it will probably turn on ok but the only way it will turn off is if you remove power. A DC SSR is constructed from an analog switch so it does not need the supply to go though zero for it to turn off.