New HT Oven "Burn In"

[Axeman58]

Ok, so here I go again with another dumb question. I have just finished up on my HT oven build, and need some advice on the following points:

1. Bringing it up to initial SS HT temps in a controlled, gradual manner to protect the element.

2. Giving the PID time to "learn" its job in the entire process.

3. Any advice on programming the Auber Instruments PID, the ramp and soak model.

I seem to recall reading somewhere that the heating element would last much longer if in the beginning it is taken to much lower temperatures and allowed a short soak, allowed to cool back to ambient temp, then taken to an increased temp, and so on. I also remember something about the PID kinda learns from doing this kind of slow burn in.

My daughters boyfriend (an electrical engineer) came to check it out, and while I had his (more or less) undivided attention, I pulled up the manual for the PID, and 2 1/2 hrs later, he was almost as confused about programming it as I am. I'm really thinking I might be doing the same with the programming as I did with the wiring of the oven...over complicating it!

To make a long story short, any help will be greatly appreciated!

 

[timgunn1962]

I've not used an Auber, so I can't really help there. I assume it's the SYL-2352 DC pulse output version to drive an SSR? There is a basic setup video on Auber's site for the SYL-2352.

If you are on an SSR, I advise setting a 2-second output cycle time.

I don't faff about with trying to give gentle starting on thermocouples. I don't ever recall seeing it advised in anything I've read and I've been involved with industrial temperature control for 28 years.

However, I do take the temperature up to effectively maximum before running the autotune in order to ensure that the thermocouple has an Oxide layer on it for the tune. If you tune it while it is still shiny, it will have slightly different response characteristics to those it will have in use once the black Oxide layer forms.

The Autotune is the controller learning process, during which it calculates the P, I & D terms. I'd advise running autotune at the lowest temperature you are likely to use, since at high temperatures overshoot is not a problem, but it is at low temperatures. If you intend to temper in the oven, I'd suggest autotuning at around 200 degC or 400 degF, from a cold oven.

Personally, I don't bother trying to give the element an easy time either, but a few short runs to low temperatures to dry things out are a good idea if you've used any mortar or may have damp bricks. None of my element suppliers have advised low temperature initial cycles, though they have given me other tips for element survival.

 

[Axeman58]

Tim, thanks for the suggestions. I think I'm in for a bit of a learning curve with the PID! I tinkered with it last nite and discovered I know less regarding setting it than I thought. I'm going directly to the Auber Instruments site to find the video you mentioned. Thanks again!