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Topic: Choosing an SSR (Read 994 times) previous topic - next topic

justjed


Quote
That's an idea too. But, what would Tim Taylor do?

I guess I am culturally deprived.

Don


From the show, Home Improvement
http://www.youtube.com/watch?v=tY5WxDqggbs
... it is poor civic hygiene to install technologies that could someday
facilitate a police state. -- Bruce Schneier

mjbmikeb

SSRs leak current when "off". The isolation is substantially worse than a mechanical relay.
see http://www.electronicspoint.com/solid-state-relay-leak-t6756.html
This may or may not be a problem for your application.

justjed

Thanks for the tip. I don't know whether that'll be problematic. When I was talking to the landlord about doing this (turning on the A/C when the aquarium goes over-temp) he was unconcerned about my using an SSR. He's a EE, so I figure if it was problematic, he'd've said something. (He's on vacation now, can't bring it up.) But I will keep it in mind.
... it is poor civic hygiene to install technologies that could someday
facilitate a police state. -- Bruce Schneier

cyclegadget


  One important thing that has not been mentioned is that you do not want to cycle power to the A/C compressor off and on without giving it a chance to settle. Basically, the "high pressure" side of the A/C needs time to equalize with the "low pressure" side before the unit is restarted. If you do not allow this time the compressor has to start under load and can burn up. Just to throw a time out there, you need to wait about a minute or two between turning the unit off and then restarting it.

Industrial A/C units have protection from quick restarts but, home units usually do not.

Mark

justjed

That part I do know about, but thanks anyway. I have percolating in my head ideas about how to, for example, switch between manual and automatic control, and how complex I want to get (likely, not very). But the auto mode will function only from noon to 8pm, or something like that, and will just turn it on and latch, and let the unit's thermostat function. And I'll put in some code to use a switch to go between manual / auto, or off / on / auto. Simplest thing is to just hit the off button on the unit at night, and then remember to turn it on in the morning, so the Arduino can then turn it on if need be.
... it is poor civic hygiene to install technologies that could someday
facilitate a police state. -- Bruce Schneier

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