Hello Arduino community,
I am on the edge of completing my bachelor's project, & I need an arduino to control my designed fruit dyrer.
It has two heaters, and TC4 thermometers equipped with 2 SSR's to control the temperature. I would like to replace these thermocouples with an arduino so it can change the temperature of each heater hourly for the value I want.
I need your guidance in connecting the two AC heaters with the DC arduino and read the feedback from the two thermocouples.
I am using K-type thermocouples for temperature measuring, and two AC (1KW each) heaters.
I dont need a digital LCD. Also I would like to install a humidity sensor.
Get (links to) the data sheets of the SSR and thermometers, in order to learn about possible Arduino connection. Modules or shields exist for thremocouples and SSR.
You may find something in this thread below. It is about "retrofitting" a commercial, non-isolated AC mains motor controller with an Arduino controllable circuit using PWM over an opto-isolator into a low pass filter. The same applies to a heater controller since these can be very similar.
Heaters can just as well use bang-bang control. No need for phase cutting or so.
There are SSRs in place already - chances are they take a 5V signal to switch, so can be controlled by the Arduino directly. For lack of details on these SSRs that's all I can say about it.
There are thermocouples in place - chances are they can be read by an Arduino as well, using an appropriate thermocouple amplifier board. For lack of details of these thermocouples that's all I can say about it.
There MUST be some kind of thermostat in place as well, something where the temperature is set. That's the part that the Arduino would replace in this project. For lack of details of this existing control circuit that's all I can say about it.
Adding a humidity sensor is easy. Get a BME280, mount it at a convenient place, and wire it up to your Arduino.
MOST IMPORTANT: Be sure the controls are totally isolated from the mains. If not you will get smoke and fire originating at your arduino. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
This might be what you're looking for. The power map acts like a variac. It can be expanded to use multiple inputs - outputs for your purpose. You dont need messenger or serial, because he used it to interface labview. You can even add lcd and set operation via buttons easy with this scheme. If you dont need high precision of the temperature swap out the pid for some other code that compares setpoint to measured, and provides output, or a time function or both. But the zc detect + heater driver part works like a charm, I tested it on a 2KW toaster with a snuberless triac that could go to 6kw. Installing sensors is no problem, analog ins are 0-5V, if the probe dosen't match you might need an amp to match the voltage range. Then you just need to calibrate it in code, for that I would reccomend using a display or serial to pc to compare calculated variable value to an instrument, and adjust ratio untill they match. Otherwise you have no feedback of your calculations. Easiest way is to buy arduino matched probes, and use their references in code. For the output be sure to use optocoupling of some sort, the guy I referenced uses an optotriac fo fire his power stage.
