Something a little off—Control Panel

[jeeppilot]

I just finished a semi-custom control panel based closely off the Electric Brewing Supply 30 amp BIAB build. I powered it up and almost everything seems to be working right.

Turning on the element switch, I hear the clunk of the relay closing and the element light is on, but dim. But it never goes out, even when there should be no power to the element. I confirmed with a multimeter there is 58V going through the boil contactor when the SSR light isn’t lit, no voltage across the SSR control terminals and the EZBoil “out” led is off.

Adjusting the temp to trigger the heat on lights the SSR led, the “OUT” led, puts the element led at full brightness and I measure 240V across the boil contactor.

So, why the residual voltage? I imagine I mis-wired something, but where did I screw it up?

https://s3-us-west-1.amazonaws.com/guide.ebrew.supply/BIAB-30a-EBSP200.pdf

 

[doug293cz]

Are you doing this testing with the element unplugged? What you describe is exactly what should happen when the element is not plugged into the controller power output.

This happens because the SSR is an imperfect switch. A perfect switch goes from infinite resistance when off to zero resistance when on. An SSR has a few 100 kilo-ohms resistance when off, and a few 10's of milli-ohms resistance when on. The current that will flow thru the SSR when it is "off" is enough to dimly light the element firing light. The small resistance when on is why the SSR gets hot, and needs a heatsink.

Brew on

 

[doug293cz]

In order for the element firing light to turn on and off, like you expect it to, you have to have a load connected to the panel power. Just don't forget to have the element immersed in water, when you do the testing.

Brew on

 

[jeeppilot]

In order for the element firing light to turn on and off, like you expect it to, you have to have a load connected to the panel power. Just don't forget to have the element immersed in water, when you do the testing.

Brew on

Doug, now I remember this residual being mentioned somewhere on here, but didn’t think it would be so drastic without a load on it. I did NOT have the element plugged in when I tested it so I will try that! Thanks for the help. Cheers!