MicroPython Forum (Archive)

@roland_vs While that would undoubtedly fix the power dissipation problem I have a doubt. I assume the purpose of using a SSR is to avoid the issue of contact wear. With an inductive load the worst potential for contact wear occurs when the contacts open at a time in the cycle where current is a maximum. There is then a risk of arcing with transfer of material between the contacts. With a parallel SSR, the SSR will have zero volts across it when the contacts open, so the triac will be off. Unless the triac is immediately forced into conduction it won't help with this problem.

The conventional solution is a snubber network to limit the dv/dt in the hope that the contacts open sufficiently quickly to prevent an arc being established. I think you'd still need that, because the triac control circuit is probably designed to turn on at a zero voltage crossing.

I'm not entirely sure what the SSR is bringing to the party compared with a properly implemented conventional relay circuit. My recollection of the theory of induction motors is rather corroded with the passing years. Is inrush current a problem?

Having snubbers is a good idea in general in order to make thing robust and safe!

On the subject of having a triac and relay, check out this article.

http://www.st.com/content/ccc/resource/ ... 356324.pdf


Regards,

Roland

Interesting article - thanks. In the examples shown, the microcontroller ensures that the triac is driven before the mechanical contacts open, protecting the contacts from any risk of arcing. Where the triac is in a module with unspecified drive circuitry this may or may not work, as far as I can see.

Lots of information to digest. Thanks for all you guys knowledge.

Sprinkfitter

I mentioned safety and SSR isolation because of the potential hazards associated with high voltages and water. I suggest you study the wiring regulations wherever you are located. With projects like this, attention to such details is obviously important.

Good luck with the project

Hello,

Could anyone suggest, helping me on pinpoint the issue and stop the break in your filtering schedule. and I also have
facing Troubleshoot an Overheated Pool Motor ... in great shape.

Hello,

You have good idea sprinkfitter, but I don't know it would work or not? Because of daily its not easy to start motor for 12 hours, but if you did this and you are satisfied with it then please tell me. I also want to do it with my swimming pool if ill get any idea ill write in the thread section.
Thank you!