Add PID to Stilldragon Design

[TopherM]

My current electric controller is a 120v Stilldragon kit built exactly as it comes, with just a solid state relay and a pentameter feeding a 2000 watt element in a 5 gallon pot for 3 gallon batches. Here's the wiring if you are unfamilar:

https://www.stilldragon.org/uploads...ller.Kit.Build.Instructions.v1.0.20131020.pdf

If I wanted to put a PID in this box, would I just directly replace the pentameter with the PID in the circuit, or maybe put the PID directly after the SSR in the circuit? Where exactly would it go in the circuit?

 

[TopherM]

Basically, could someone send me a wiring diagram for a single PID, single SSR, single thermocoupler? Thanks!

 

[stratslinger]

The wiring would get a little more complicated... Yes, you would replace the potentiometer with the PID, but in a slightly different way, and you'd likely need to change out the SSR as well. The SSR should be labeled as to what input it takes on leads 3 & 4 - can you check that and let us know?

Typically, a PID drives an SSR that accepts a 12V DC input. Assuming what you've got is really 120v, you'd need to take a pigtail off of the white (neutral) wire and patch that to the neutral lead on the PID, then pigtail the black input and patch that to both the PID and SSR hot inputs (basically, keep one connection to the SSR as you have it now, and another to the hot lead on the PID).

Then you'd run the 12v control and ground from the PID to the SSR control (where the potentiometer currently connects), and attach a RTD probe to the probe inputs on the PID, and you're done.

The main gotchas here are 1) the input signal your current SSR will accept (is it compatible with a standard PID output) and 2) is that enclosure big enough to house a PID? (It doesn't really look it from the pictures)

 

[dyqik]

The problem is that the StillDragon kit relay is an SSVR, not an SSR. An SSVR is an analog proportional controller, while an SSR is an on/off switch. The cheap PID units have on/off low voltage DC outputs, and expect to switch the element on and off. An SSVR can't do that (easily). Most importantly, (according to the Auber page on the SSVRs they sell with pots, anyway) the voltage you are regulating will be present on SSVR inputs, so 120V AC in your case. You really don't want that connected to a PID SSR output.

But a cheap PID can be bought as a kit supplied with a 25A SSR and heatsink. In that case, you will replace the SSVR with the SSR.

Or for certain uses, you can connect the SSR in series with the SSVR, and have the PID unit switch the element on and off, and use the potentiometer to control the power of the element when it is on. That can be useful for preventing scorching in a RIMS setup, while keeping plenty of power for mash-out steps.

 

[dmcman73]

You won't be able to reuse the Still Dragon setup, as dyqik stated, the still dragon does not use an SSR. If you want to use a PID you'll need an SSR, PID and a switch to turn the power to the coils on and off. You can start with Kal's great setup here and just use the boil kettle wiring: http://www.theelectricbrewery.com/control-panel-part-2?page=11

Kal's is a 220V setup, but you can adapt it to 120V. It would be Hot lead in Power switch for entire unit -> Pin 9 on the PID -> Power switch to turn element on and off (optional) -> Input leg of SSR. Then Output leg of SSR -> Hot leg of the heating element. Then you can run your neutral from the power cord to pin 10 of the PID and the neutral of the heating element. You'll then need to wire up the thermo to the PID.

just keep in mind that if you purchase different PID's than what Kal uses, make sure there is a manual mode on it and also, the pins may be different to reference the manual for it.

 

[TopherM]

Thank you for the replies! Sounds like I'll go ahead and build a new controller based on a single version of that Electric Brewery diagram.

If I add an on/off switch, where would it go in the circuit. Between the SSR and the power source?

 

[dmcman73]

Thank you for the replies! Sounds like I'll go ahead and build a new controller based on a single version of that Electric Brewery diagram.

If I add an on/off switch, where would it go in the circuit. Between the SSR and the power source?

To shut down the entire system, put a 120V switch between the plug and the rest of the components in the box.

If you want to add an extra switch to turn the heating element on and off while keeping the PID on (useful for programming the PID without the element turning on) Put a 120v switch between the Hot lead going into the SSR to cut the voltage off from going into the SSR.

 

[dyqik]

My RIMS box has the switch between the SSR and the output, on the 120V hot lead. This is so I can check the SSR functionality via its LED and set up the PID without the element coming on. I didn't bother with a mains power switch at the input - the input power is on a computer type power cable connector, so I can always just pull the plug.