Fermentation Chamber Help

[mnHawk8]

Thanks guys for taking the time to think through this with me. I really appreciate it.

ECC - I am 95% sure I have it wired just like you say as I've checked that a couple times.

I am using 10A SSRs as I assumed that would be enough. I do have some 25A and 40A sitting around for other purposes that I could switch out. That thought did occur to me but I wanted to make sure my configuration was right first.

[mnHawk8]

Thanks guys for taking the time to think through this with me. I really appreciate it.

ECC - I am 95% sure I have it wired just like you say as I've checked that a couple times; but I will check it again tonight.

I am using 10A SSRs as I assumed that would be enough. I do have some 25A and 40A sitting around for other purposes that I could switch out. That thought did occur to me but I wanted to make sure my configuration was right first.

[ohio-ed]

An SSR will "leak" voltage when there is no load applied (or a very small load).
If you put a volt meter across the output of the SSR, you will get misleading results which may be why your fan turned. It would depend on the size of the fan. I've found it pretty easy to test the output by plugging a lamp in with a 60watt bulb (smaller may work, larger will work).

As ECC said, you should be able to test the BCS output. It should be 0 or 5vdc.

Good luck.

[ECC]

Yes, i agree with Ed. SSR's don't physically switch the output off like a relay would, they put the put a very high impedance between the output terminals. What this means is if no load (or a very very small load) is connected, it will 'float' up to the voltage.

This is why I asked for the specific part number of your SSR. I'm not too concerned about the maximum current rating (10 or 25 amp), I'm more concerned with the minimum load rating which will also be spec'ed in the datasheet. Typically this value is on the order of milliamps, and a fan should pull it down easily. But on the off chance that the specific SSR has an unusually high minimum load, it would behave as you describe.

[mnHawk8]

I purchased my SSRs from Auber Instruments http://auberins.com/. For some reason my work has their site blocked so I can't get to the datasheet until this evening.

Also, the fan was a pretty small one (one of the clip ons).

Thanks again for all the help guys.

[mnHawk8]

Well guys, it was completely a mess up by me (which is kind of what I figured but just couldn't figure out where). I spoke with Suyi at Auber and he pointed out that their 10A SSRs are DC, not AC. My freezer is AC. I completely missed that when I bought them.

I'll switched out the 10A for the 25A and everything works just fine.

My bad....thanks for the help; it's really appreciated.

[rcrabb22]

Cool! Mystery solved! Live and learn!