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Hii. How do i change the PID constants for three 135 W 220VAC band heater in your ac pid temperature project. Do you have sample solving or what. Thank you for your non stop help to us beginners :) God bless
by (220 points)

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Well, go in the code and start tuning the Kp, Ki and Kd constants. Start with Ki and Kd = 0 and Kp = 1. Then start increasing the values till you get good PID result, so the temperature is not oscillating, not overheating or underheating. You will have to make a lot of tests till you get good results. Keep up!
by (34.8k points)
Do i have to change the kp, ki, and kd all at the same time or once at a time. Is there a formula on how to get those constants? Thank you for your answer :)
Well there are formulas but that's very difficult and you should make the graphs.

Just do it one by one. Have in mind the P is proportional so it will oscillate if too big. The I is integral so it will slowly add a tiny value each loop so it should be small and act only for small errors. Let's say you have 3 degrees error. You want the integral slowly add up till you get eror 0. And the derivative will affect the speed. So at the beggining is high and then it will get low. Make some tests. Keep up!
Thank youuu. I'll inform you right a way once i've achieve it
Hi! I think i finally got the right values. I set the target temp at 160 and i came up with an output range from 154-167. I used the serial plotter of arduino to see the trend over time. The output range stay until it overheat at 2500 time. Im thinking it is because i don't have heatsink in my triac and my triac overheat ?* my PID value are 96.71, 2.93, and 1.305 respectively. Thank sir for your help. More blessings and power for your projects :)