Precision PID controller

Discussion in 'Furnaces and their construction' started by Perseus123, Feb 16, 2021.

  1. Perseus123

    Perseus123 Lead

    Anyone know any PID controller for a kiln or any heating hot plate to keep a precise temperature to the decimal and hold it there for days without it fluctuating?
    I don’t need high temps. 400c is fine. I bought an Auber PID but it’s garbage trash. Keeps fluctuating the temps and doesn’t stay on exact temp set. Also with auto tuning. Absolute precision accurate.
    Anything that avoids on/off bull if at all possible.

    or maybe it’s the cheap SSR that won’t allow precision temps?

    something like this video shows: constant same temp.


    thanks.
     
    Last edited: Feb 16, 2021
  2. Melterskelter

    Melterskelter Gold Banner Member

    I’m no expert, but hysteresis is a factor that can be adjusted in PIDs. Have you tweaked that in your settings?

    Denis
     
  3. Perseus123

    Perseus123 Lead

    No I never messed with the hysteresis settings.
    I’m no expert either.
    I use an SSR and pt100. I don’t understand why cant these PID just keep a steady current to keep the exact temp. It goes on/off.
     
  4. PID stands for Proportional Integral Derivative temperature controller, this means it measures any overshoot or undershoot errors and makes corrections on the fly. This means that it's going to get more precise the longer you run the temperature controller. It also means each time you turn it off it will go through the whole procedure from scratch. Even expensive quality units will do this if using the PID method to control temps. With a lot of experimentation you can alter the preset values to reduce the initial errors but that's about all.
     
    Last edited: Feb 16, 2021
  5. Perseus123

    Perseus123 Lead

    Oh ok. Yes I understand.
    I left my kiln running even just for 50c temp target, it kept going up down but close but then it got out of auto tune . Shouldn’t it stay in auto tune until it stabilizes to precise temp?
     
  6. Jason

    Jason Gold

    This was a good idea starting this thread. There are guys here that really understand the inner workings of this thing.
    I'm lucky to have mine working so well. Mine is on a kiln with typical resistance elements. My Auber PID can gently throttle the electricity going to those to
    maintain a precise temp. All PIDS work with this on/off bull. It's not a resistance type device! It speaks in ones and zeros.

    Please tell me your hot plate isn't an induction type hot plate????
     
  7. It should get better over time, not worse, what do you mean by "Auto tune" is that something specific to your particular controller?. PID algorithm runs all the time making corrections to arrive at a constant temperature but if the hysteresis is set to a few degrees then it will allow the temp to vary by the programmed hysteresis value.
     
    Jason likes this.
  8. Perseus123

    Perseus123 Lead

    mom not sure if my hot plate is a induction type:
    https://www.labdepotinc.com/p-59784...Ii9jw9Lfv7gIVFMzICh1gpAEIEAQYBCABEgJghPD_BwE#

    Not sure about my kiln either.
     
  9. Perseus123

    Perseus123 Lead

    I have a syl2352 Auber PID.
    Auto tune let’s the PID figure what the parameters should be set up all on its own I guess.
     
  10. That hotplate has an inbuilt temp controller with feedback so adding a second controller is going to make the two controllers fight each other. Not to mention turning the inbuilt controller off and on with a second external one will reset it's microprocessor.

    Just use it on it's own and maybe wrap some suitable thermal insulation around whatever you're trying to heat, that could even be aluminium foil to trap some hot air.
     
    Jason likes this.
  11. Perseus123

    Perseus123 Lead

    Oh darn.
    I had a friend who used a PID on his hot plate and it worked for him he says. He does not have the same hot plate and did not use the same PID.

    I’m looking for precision temps and long dwell time. The hot plate on its own goes up by five degrees and is not precise.
     
  12. Jason

    Jason Gold

    EXACTLY!

    You need a "dumb" old school hot plate to utilize the accuracy of the Auber PID.
     
  13. Perseus123

    Perseus123 Lead

    I was trying to use my PID as a plug and play setup. Maybe that’s what’s causing all the problems even with the kiln I have.
     
  14. You'll have to buy a non smart hotplate or something. I put a similar REX C10 controller on a $15 rice cooker heater element to get what I wanted.

    Screenshot from P5140005.AVI.png
     
    Last edited: Feb 16, 2021
    Perseus123 likes this.
  15. Jason

    Jason Gold

    Same applies to the kiln. I set mine to MAX and let the auber control the temp.
     
    Perseus123 likes this.
  16. Perseus123

    Perseus123 Lead

    Ok thanks. That helps a lot. I will see what I can do. Unless I can just re wire my kiln to my PID and SSR to get exact temps?
     
  17. Perseus123

    Perseus123 Lead

    Yea that’s what I was doing. Temp got close to target temp but it kept fluctuating up and down. Since I was looking for precise temps it won’t work for me.
     
  18. What sort of kiln is it?. If it already has some form of temperature control with sensing and feedback then that will have to be disabled.
     
  19. Perseus123

    Perseus123 Lead

  20. Jason likes this.

Share This Page