Temperature control system... Experts, help! ! !
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These past few days I encountered a strange situation: A Honeywell temperature controller is connected to two relays (normally open and normally closed), as well as an electric control valve of the on/off type. With this wiring arrangement, the temperature is maintained within 1 degree of the set temperature! It’s stable… The electric control valve moves at most 1 or 2 millimeters up or down. With the same wiring and under the same operating conditions (a distance of 1 meter apart), using a different temperature controller together with another electric control valve fails to maintain the desired temperature; the temperature fluctuates by up to 20 degrees around the set value. The operating conditions are definitely the same, the wiring is fine, and the PID settings as well as other parameters of the temperature controller are identical. There’s definitely nothing wrong with the electric control valve! It’s strange that for on-off type electric valves, they are either open or closed… But the valve connected to Honeywell stays in an intermediate state, not moving; it rises slightly when the temperature drops by 1 degree, then stops again! The temperature drops a little bit at a time·Stop! But K-degree is at most 5 millimeters, and the display shows at most 10 percent! Strange: 2. Identical operating conditions – one TaiDian unit and one Honeywell unit; it is said that they are both produced by the same company. The parameters are the same; TaiDian follows the settings of Honeywell, including PID values and third-level parameters. The valve moves back and forth throughout its full range of motion: either it is fully open, resulting in excessively high temperatures, or it is fully closed, resulting in extremely low temperatures. It never stops moving! The situation is urgent·Honey has already placed an order·but I can’t figure out the tactics involved in this! ! ! The Honeywell 1040701000 maintains a stable control within plus or minus 1 degree! ! ! If you know, you can call directly or send a private message~~~
Let’s talk about the approach: First, when it comes to control, one needs to analyze the control object, examining its characteristics and whether they change. Secondly, you also mentioned that the situation with the valves has changed, and it seems there is some oscillation. Then it is necessary to analyze how the valves were used in conjunction with the controller, and whether they were simply just valves. An accumulation=integration function has also been implemented in the valve actuator and accessories. As for the use of two solenoid valves to control the regulating valve, reference can be made to the working principle of piezoelectric valves in intelligent valve positioners.
The only difference between the two valves is the speed of their motors – one operates faster while the other operates slower. Theoretically, there isn’t much difference between them. What’s strange is that the Honeywell temperature control device stops sending signals once the desired temperature is reached; otherwise, it continues to send signals. Switching valves must be either fully open or fully closed, right? The TD power supply temperature controller is a control valve that operates in either fully on or fully off mode; as a result, the temperature difference is quite large·