Tuning BERME REX-C100FK02-VAN Temperature Controller

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Introduction: Tuning BERME REX-C100FK02-VAN Temperature Controller

About: Mechanics is the paradise of the mathematical sciences because through it you can reach the fruits of mathematics. Leonardo da Vinci (1452-1519)

Briefly about BERME REX-C100-FK02-V*AN temperature controller settings

Recently I was asked by a friend to assembly such a temperature controller in a plastic box, in order to maintain the melting temperature of a DIY plastic injection mold. It was an easy task as was the wiring (the tiny electric heater is only 60[W]) and the result can be seen in the atached photos.

The box content:

- plastic toolbox, dimensions (LxWxH): 24x14x11[cm] overall, 22x12x9[cm] inside

- controller BERME REX-C100-FK02-V*AN

http://www.rkcinst.co.jp/english/pdf/c_02e.pdf

http://www.rkcinst.co.jp/english/pdf_manual/imnzc22e1.pdf

- electronic relay FOTEK SSR-40 DA with aluminum heat sink (heat sink really necessary over 10[A])

http://www.fotek.com.tw/index4.asp

http://www.fotek.com.tw/pdf/2013515_90632265.PDF

- thermocouple type K (0÷400[°C])

https://www.thermocoupleinfo.com/

- AC/DC 5[V] 2[A] power supply for two mini fans (fans really necessary over 12[A])

- 250[V] AC male/female connectors for power supply, heater and thermocouple

- mini toggle switch for controller's internal alarm.

I do not intent to discuss this content or the wiring, but the settings of the controller. When I finished to assemble everything in the box, I switched it on (with factory's default settings) and I observed the requested temperature was 8÷10[°C] exceeded before stabilization. Then I searched for some official setting procedures or even tuning information for this type of controller and I observed the same manufacturer carelessness as the other users I believe did before me. For example:

- instruction manual (two versions found):

http://www.fmfranklin.com.au/products/data/rkc/c100inst.pdf

https://www.rkcinst.co.jp/english/pdf_manual/imnzc22e1.pdf

Mounting and wiring perfectly explained and just some quick setting indications.

- setting manual:

http://www.fmfranklin.com.au/products/data/rkc/c100set.pdf

This material deals with all series from C100 to C900 in a perfect mess and with such insufficient explanations. As if the document was addressing just to controller specialists and not to domestic users. What really encouraged me to continue, was the information my predecessors have shared all over the WEB (YouTube, forums and Instructables). It took me sometime to read it almost entirely and to try many setting combinations. These common explanations I used to understand how the algorithm works:

https://www.omega.com/temperature/Z/pdf/z115-117.pdf

https://www.eurotherm.com/pid-control-made-easy

http://www.newportus.com/products/techncal/techncal.htm

All my results are concentrated in the tables and diagrams atached.

I took advantage having a quick little system and I visualized his behavior in 20[min] tranches. Then I took another advantage having the possibility to disconnect the thermocouple and the heater and I let the mold outside (5[°C] winter temperature) to cool for an hour. Then brought it inside (at 20[°C]) and repeat measurements with different settings. All records were done manually, starting the moment the controller showed 20[°C]. Most relevant curves (of the 20) are:

Curve 1: P=0, I and d were not accessible, manual control, the process is self regulating.

Curves 2 and 6: the influence of P (big value to have a quick damping)

Curves 2 and 3: the influence of I (same as P)

Curves 3 and 4: the influence of d (same as P)

Curves 4 and 5: tuned controller for SV=100[°C] and 260[°C]

Curve 7: just another setting to compare.

The controller reaches smoothly the desired temperature and now remains there without exceeding it more than 0.5[°C] that cannot be displayed. I did not have access to PGdP variable to set it for one decimal shown. First minutes of history must not be interrupted by any adjustments, the algorithm is gathering data in order to evaluate the evolution of temperature gradient towards SV. The relay lamp is steady on at start, then blinking increasingly rare until it flashes just to sustain the thermal equilibrium. With the right settings this controller does a good job.

I would like to remind two things: first, it is good to be familiar with this algorithm and second, the setting values I found correct for my project may not give the same results if simply copied for another.

I hope this experience will be helpful to others.

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