Apr 3, 2011
Revised Sous Vide PID Calibration
We want to quickly amend how to calibrate PID parameters for the sous vide. Experience now shows that our last calibration often overshot more than the default settings.
Although we took data over a few hours for our old settings, the true results only came to light after we played with our vide for a month. Evaporation is more complex than we expected, but after we tinkered around with some fudge factors everything turned out all right.
In our formulas we varied parameters all over the place until we got something that converges as fast as possible in most situations (i.e. small pots, big pots, different heaters, covered, uncovered.. etc). However, this diagram simulates a middle-of-the-road model of a semi-covered pot 30 cm in diameter, with 20 cm of water and a 1000 W heater for heating and evaporative cooling. You can see in the figure the original temperature curve (green), after auto-tuning (red), and with our new PID parameters.
The optimized parameters: P: 0.2%; I: 2000 sec; D: 0 sec.
To put these into the JLD 612 PID controller: Press SET; enter code “0036″; press SET; press up or down to P; enter 00.2; press SET; press up to I; enter 1999; press SET; press up to d; press SET; enter 000; press SET. Press up or down to End; press SET. The parameters will remain set even after your controller is unplugged.
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