What optocoupler to switch mains on and off?

Discussion in 'General Electronics Chat' started by daviddeakin, May 13, 2014.

  1. daviddeakin

    Thread Starter Active Member

    Aug 6, 2009
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    I'm trying to find a solid-state solution for switching a mains supply on and off. That's it. No phase control, just on and off.

    I assumed I would be able to buy an opto-triac, where all you have to do is turn on its LED and hey presto, you have a high-current solid-state switch. But while lots of manaufactuers make opto-triac drivers (so you have to add an extra triac), I can't find any such thing as a plain-jane opto-triac for power applications (a couple of amps at 240Vrms, say).

    Solid-state relays (opto-MOSFETs) don't seem to have enough current cabability to handle mains applications reliably either.

    What am I missing? Do such things not exist?? I'm not talking hair-raising power levels here, just a couple of amps would be ample!
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
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    For that kind of current they need to have some size due to power dissipation. If they are to small in size they will overheat. Even a Triac will need some kind of cooling finn for that kind of voltage/current combination
     
  3. Ramussons

    Active Member

    May 3, 2013
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    a Zero Crossing Opto Coupler (like MOC3042) can be used for triggering a BTA series Thyristor like shown. An Optocoupler is only an interface and cannot handle more than a few millamps.

    [​IMG]

    Ramesh
     
  4. daviddeakin

    Thread Starter Active Member

    Aug 6, 2009
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    I see- that's the impression I was starting to get. Thanks!
     
  5. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Complete assemblies are available; google "solid state relay." There are also some kits available, which may come up in your search.
     
  6. Alberto

    Active Member

    Nov 7, 2008
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  7. enggricha

    Member

    May 17, 2014
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    there are quite a few solid state relays out there, probably you are not looking in the right places.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Here in N.A. the Opto22 range cover it, not sure if available in the U.K. however?
    Max.
     
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