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Ideas to prevent Failures of Solid State relays

Discussion in 'Electronic Basics' started by karthik, Jan 10, 2006.

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  1. karthik

    karthik Guest

    I am using Solid state relays to On/Off heaters so as to control
    temperature.
    In case if heaters get short,immediately the Solid state relays ( SSR )
    also gets short and
    I need to change new one.Even though I have Fuse protection the SSR and
    Fuse gets blown.
    Since the Cost of SSR is high,I have so many troubles.

    So any one Please suggest some ideas to prevent SSR failure.Is there
    any protection like
    Varistors , RC circuit to prevent this
     
  2. Pooh Bear

    Pooh Bear Guest

    You answered your own question The SSRs are broken when the heater is a
    short.

    Fix the problem with the heaters !

    A super fast fuse combined with derating of the SSRs may help too.

    Graham
     
  3. Jamie

    Jamie Guest

    yes, SSR's can short if the load they are
    driving shorts how ever, in cases like we have
    at work we have line fuses that are rated much
    lower than what the SSR is and thus you would think
    they shouldn't short but they do at times.
    the problem we had at work was not so much the
    load but the inductive energy and unbalanced load
    effects that multiply the voltage above the limits
    of the SSR.. that is most likely your problem.
    we solved our problem by running the lines to the heaters
    spaced apart from other lines and used a TVS on each SSR
    brick.
    now if there is a loose connection or short, only the
    fuse blows if needed.
     
  4. Phil Allison

    Phil Allison Guest

    "Jamie"

    ** If an SCR or Triac is overvoltaged by a spike or similar (in the off
    state) then it simply triggers on for the rest of the cycle. This is not
    destructive to the device.

    So it is not destructive to SSRs either.





    .......... Phil
     
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