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  • #16
    Re: PID

    Originally posted by Sammy link=1189748485/0#13 date=1192597318
    How "big" should the heat sink be Mark? and whereabouts did you mount it? Ive read quite a few write-ups of peoples PIDing and im not sure if many of them put a heat sink in.
    All other things equal, having a heat sink is better than not having a heat sink. But the current demands for your 220V Silvia will be very low - the heater should draw less than 5A.

    I have measured Crydom SSR baseplate temperatures for 110V Silvias (which draw 8A) and found that the SSR temperature stays well below the manufacturers threshold for a 10A load. And this was with the SSR exposed to air with no heat sinking of any kind.

    Because it is a trivial matter to smear a little heat sink compound on the frame of the Silvia before fastening the SSR, go ahead and do it. But I am convinced this step has very little benefit for this specific application (especially for a 220V machine that draws even less current than the 110V model).

    While the machine is idling, the duty cycle of the SSR is going to be around 8%, further reducing the need for heat sinking.

    Please be sure and incorporate the following elements in your plan:

    - use a good grade of stranded hookup wire, with a min. temp rating of 105C
    - try and find wire that is rated for use in appliances (usually designated as AWM)
    - use a safety cover over the high voltage terminals of the SSR, especially if mounted below the group
    - run a ground wire to your enclosure if it is made of metal

    Above all, be safe and have fun with it.

    Jim

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    • #17
      Re: PID

      Well explained Jim [smiley=thumbsup.gif],

      Mal.

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      • #18
        Re: PID

        Yep, great explanations! Thanks guys!

        -Sammy

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