Question about Controller (PJ wiring)

[CCinBR200]

I have been working on a controller and electric kettle. I used a diagram from PJ. Did a test of the system and noticed that the temperature (PID controlled) overshot - by 10 degrees! before I stopped.

Went back to study the diagram. Now I'm thinking that the PID is only controlling one 120v leg and that the other leg will keep heating constantly. This will be a problem for me if I am trying to use this to hold my mash temp steady.

Have I done all this work only to have a device that can't hold a temp?

Thanks for any help.

 

[nobadays]

I had a similar question when I built my controller thinking there would always be power to one side of the element. Not true...well at least extremely little power. When the contactor is open it interrupts the circuit much like turning off a light switch. Your problem is likely that your PID is not properly tuned.

Go here: http://www.theelectricbrewery.com/control-panel-setup and read how to do this. Thanks to Kai at the Electric Brewery

Cheers!

 

[BrotherGrim]

Actually the problem is non-existent. In order for electricity to flow through your element, both of the lines must be connected to provide a path. The two 120V lines are opposing phases and when power is applied, the direction of current flow is from Line 1 to Line 2, then Line 2 to Line 1, etc 60 times per second.

No worries

 

[CCinBR200]

This is a relief! Thanks for the replies. Now to tune the PID......