ITC-106 not tunable at all

I have wired up an ITC-106VH using a K-type thermocouple and an SSR to control the temperature of a toaster oven, with the goal of maintaining Sv=400F at +/-3F.

With the factory default settings for the P=50, I=30, and D=8 values, I see overshoots of Sv by +60F initially, and then settles at a 5.2 minute oscillation period of -7F to +34F from Sv.

Using the autotune methods yields nearly identical results.

Failing to perform properly either in factory default mode or autotune mode, I attempted various empirical manual tuning methods which I observed to have no appreciable effect different from my first attempts:

  • Operate in P mode only, by setting I=9999 and D=0 and vary the P value looking for a stable Pv. When trying P between values of 1 and 5000, no significant changes in behavior were noted and the variance is similar to that of the factory default values:

  • Operate PI mode, setting P=100 and changing I values. I tried many values if I between 375 with no difference. As a brand new user, I can only attach one media object, but the absence of any effect on the I value and the similarity of the Pv curves is unchanged from the P-only attempt at tuning.

One other thing of note: regardless of PID values, in every situation described above, the ITC-106 turns off the output exactly when the temperature rises through Pv=Sv, and turns the output back on exactly when falling through Pv=Sv…as if none of the proportional, integral, or derivative terms are having any impact at all on the system.

Do I have a defective ITC-106 or am I doing something wrong, because I’ve been testing this thing for three straight days and am getting close to getting rid of this PID controller.

Hello,
If you have high requirements for temperature accuracy, maybe the ITC-100VH will be more suitable.
The ITC-100 series is an industrial thermostat with a wide temperature range, suitable for a variety of heating systems.
The ITC-106 series is a household controller, suitable for slow cooking, wine making, etc. If professional control is required, it is recommended to purchase the ITC-100 series.

Hello,

The curves should flatten (sadly sometimes after a long time) around Sv even with an “household” controller such as the ITC-106 (if it works according to its specifications).
As etchorner said, if none of the proportional, integral, or derivative terms are having any impact at all on the system, there shoud be a problem with the PID (either configuration (is there a PID mode vs a direct mode ?) or the PID device (defective)).

Regards

Not particularly a requirement for precision, but the ITC-106 was only giving me control over a 50°C range (+40°/-10°) and was not responding to any useful degree to any manual or automatic tuning attempts. Presuming on solid facts that the ITC-106 unit was defective, I’ve replaced it with an ITC-100VH. With only a few manual tuning runs, it now controls my tempering oven to ±0.1ºC. Much better, although the tuning parameters are not strictly PID…but it works.

I retired the bad ITC-106 to use as a temperature readout on my gas forge…it works fine in a non-controlled environment.

@etchorner
What do you mean by : the tuning parameters are not strictly PID ?