Method for Determining the Positive/Reverse Action of a Regulator When it comes to automatic adjustment systems, one of the most critical steps after defining the control strategy and determining the regulator’s positive or reverse action is tuning the P, I, and D parameters. Based on years of field experience, the process of adjusting these parameters can vary depending on the specific system and application. It is always recommended to refer to the project documentation and follow best practices to ensure optimal performance. Before starting the tuning of P, I, and D parameters, it's essential to confirm that the closed-loop system uses negative feedback, meaning the product of the controller gain (Kc), the valve gain (Kv), and the process gain (Ko) must be greater than zero (Ko * Kv * Kc > 0). This ensures the system remains stable and responsive during operation. Understanding the gains is key: - The process gain (Ko) is positive if the measured value (PV) increases when the actuator opens, otherwise it is negative. - The valve gain (Kv) is positive if the valve opens with an air or electric signal, and negative if it closes under the same conditions. - The controller gain (Kc) determines whether the regulator is in reverse or direct action. If Kc > 0, it is a reverse action; if Kc < 0, it is a direct action. Proper configuration is crucial before commissioning or parameter tuning. Before setting any PID parameters, ensure that the measurement is accurate and the valve operates smoothly. During the tuning process, it's important to communicate with the operators and monitor the production status closely to avoid any safety risks. When adjusting the parameters, start by switching to automatic mode, then tune the secondary loop first, followed by the primary loop. Use step changes in setpoint or output, observe the response, and make adjustments accordingly until smooth control is achieved. Empirical PID tuning values are often used based on the type of process: - For flow control: P = 120–200%, I = 50–100s, D = 0s; - For pressure control: P = 120–180%, I = 50–100s, D = 0s; - For liquid level: P = 80–300%, I = 60–900s, D = 0s; - For temperature: P = 120–260%, I = 50–200s, D = 20–60s. These values are not fixed but serve as a starting point. In practice, system behavior may require fine-tuning. It's also important to ensure that the valve and positioner function properly, as poor valve response can hinder automation success. In cascade control systems, the inner loop behaves like a valve in the main loop, always maintaining a positive gain. The resulting PID settings usually produce a first-order characteristic, though second-order damping is possible in theory. When initiating the automatic loop, ensure smooth operation across all sections. Avoid large fluctuations in key parameters, and maintain stability in auxiliary equipment such as pressure, level, and temperature. Coordination with process operators is essential—clear communication about the procedure and potential impacts helps prevent unexpected issues. Before commissioning, verify all configurations rigorously. Check signal flow and logic to prevent errors. Ensure manual override options are available so that the system can be stopped quickly if needed. When starting the automatic loop, begin with larger proportional and integral settings, gradually narrowing them down while monitoring the system response. PID tuning methods include empirical testing and the critical proportional method. The latter involves increasing the proportional band until the system oscillates at a constant amplitude, then calculating the appropriate P and I values. However, this method is less effective for systems with significant time delays. Ultimately, successful PID tuning requires patience, observation, and a deep understanding of the process. By following these guidelines, you can achieve stable and efficient control in your system. Introducing the reliable and efficient LiFePO4 Cell, with a nominal voltage of 3.2V, perfect for powering your devices and equipment with ease. These cells are designed with advanced technology, ensuring a stable and consistent power supply to your devices. The Lithium Iron Phosphate (LiFePO4) chemistry used in these cells makes it the perfect choice for high-performance applications. These cells have excellent discharge characteristics and a long life cycle, making them a cost-effective and eco-friendly option. Lifepo4 Cell,Lifepo4 Battery,Lithium Iron Battery,Cylindrical Lifepo4 Battery JIANGMEN RONDA LITHIUM BATTERY CO., LTD. , https://www.ronda-battery.com