This may be a dumb question, but, given the same load (say 23amps), with PID control, with the same mounting, will a 50A SSR run cooler than a 25A SSR?
I read this somewhere, and didn't know if it was true.
I have a custom aluminum enclosure, and i was thinking if i could mount the SSR's directly to teh enclosure without a heat sink.
What do you guys think?
Solid state relay question
Re: Solid state relay question
You should be able to mount the SSR for the lower amperage circuits inside the case. Things like pumps and gas valves draw very low amperage. I would caution you against mounting any SSR related to a heat exchanger water heater element inside a case. You will have some heat. The higher amperage should, technically, produce less heat, however it will still get hot.
Re: Solid state relay question
I thought this was true, it makes sense. But I looked at the datasheet for an SSR:sjlammer wrote:This may be a dumb question, but, given the same load (say 23amps), with PID control, with the same mounting, will a 50A SSR run cooler than a 25A SSR?
http://forum.embeddedcontrolconcepts.co ... 4&p=27#p27
If you look at the current derating curves, you'll see that the slope is the same for different flavors of SSR's. For example, running a 25A ssr at a load current 20amps requires a power dissipation of 20 (not sure the units). And running a 50A ssr at 20amps yields the same power dissipation, although at a slightly higher base plate temp. Those charts aren't exactly easy to understand, so I could be way off here.
Aluminum is an excellent heat conductor, so your enclosure will probably make a good heat sink.