A50 Humidifier Current Sense Relay...Schematic!

[KMoffett]

https://www.skuttle.com/pdfs/a50_install.pdf
OK it's not repaired, but I now know what's inside. This is a control that senses the AC current when a motor turns on. One wire of the motor is threaded through a metal U-bracket in the end of the case. The black and white wires, then act as a switch for an external 24VAC control circuit. Mine was always switched-on. When I open the case I thought great!...all the components are standard off the shelf parts. I traced out the circuit and drew up a schematic. Bench tested it and everything worked...except the one custom part...the sense coil. It was open. Anyway, I thought someone else might interested in the circuit design.

Ken

 

[Sceadwian]

According to your schematic it's just a transformer. Unless you can get an exact replacement you're definitly going to have your hands full making a new one that matches the old one since you can't just measure the values that you need from the existing one. You could carefully take apart the old current sense transformer carefully noting the number of turns and simply replace the wire new over the old core.

 

[KMoffett]

A current transformer. One loop "primary", through the metal U-shaped strap core. The rest of the core is a screw through the "secondary" coil on the PCB. The square bobbin had a gazillion turns of hair fine wire. Didn't want to spend my time rewinding it...just bought another relay. The schematic was just because I wanted to see how they powered a "closed" active switch in series with the load.

Ken

 

[bmyers77]

Ken,

Thanks for the schematic - exactly what I was looking for...saved me the RE effort....thank you.

Brock

 

[KMoffett]

Good! I posted in the hopes that it might help someone someday.

Ken