Re: PID
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
Originally posted by Sammy link=1189748485/0#13 date=1192597318
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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