PID Question

[C.I.TR3]

Hi All,

First post on the forums although I have been here reading for a long time. Another new maker but I believe I have read all the stickies at the top. I have what I hope to be a simple first question. I am looking to buy a PID controller. Initially I will use the controller simply as a pyrometer for my gas forge. In the future I may want to use it to make my forge PID controlled (single blown burner). I have read the various threads and looked at the PIDs at Auber but I am still not sure which one to get. Specifically, do I want relay output, SSR output, or Built-in SSR output? I think I want SSR output but the description of the relay output says that I would not need an SSR. I may upgrade to the unit with the Ramp/Soak controller just so I can have some flexibility in the future for an oven. Thanks for the help on this specific question and thanks for all the help over the last couple of years. This is a great forum with lots of people willing to share their expertise.

 

[jawilder]

I believe your question is answered here: http://www.bladeforums.com/forums/showthread.php/523845-Pid-controlled-motorized-pressure-regulator

Lots of good info there from Stacy (our moderator)

 

[Stacy E. Apelt - Bladesmith]

Relay control is when the PID's internal relay act as an on/off switch that turns a controlled device on and off. Usually there are NO, NC, and C (common) terminals. A signal light or alarm buzzer would be controlled from this type output. Small current draw loads can be connected here, too (like a small cooling fan).
SSR output is a low voltage DC output that will turn an SSR on. This is the most common type of PID control on a kiln/forge.
Built-in ( internal) SSR is when the PID has a solid state relay built into it. This allows the control voltage to be directly connected to the PID. This usually is not what we want for a kiln, as the kiln current creates too much heat for most PID units to radiate.


Cliff notes answer - SSR output/control is what you want. Most PIDs have both relay and SSR contacts on the terminal strip. Get a heat sink for the SSR ( some SSRs have built in heat sinks) and mount them away from the PID so the sensitive electronics do not get overheated.

 

[buckaroo2219]

If you think you will be building an electronic oven in the future you it would be best to get the programmable ramp soak PID. The one with the external SSR. I just finished building a knife kiln and used the programmable.