Prosesskontroller

Prosesskontroller, or process controller, is a device or software system used in industrial automation to regulate a process variable, such as temperature, pressure, or flow, by adjusting a manipulated variable to keep the process at a desired setpoint. It is the core component of a closed-loop control system, designed to maintain stability and efficiency.

A typical prosesskontroller measures the process variable with a sensor, compares it with the setpoint, and computes a corrective signal with a control algorithm. The signal, applied via an actuator, alters the process input, forming a feedback loop that reduces the error over time.

Common algorithms include PID (proportional–integral–derivative) control, on-off control, and more advanced model-based or adaptive schemes. Modern controllers are digital and are typically embedded in PLCs or distributed control systems (DCS), with features such as auto-tuning, remote monitoring, and alarm handling.

Tuning adjusts the proportional, integral, and derivative parameters to balance response speed, overshoot, and steady-state error. Techniques include empirical methods such as Ziegler–Nichols or Cohen–Coon, as well as auto-tuning in many devices. Performance is evaluated using metrics like rise time, settling time, overshoot, and integral error.

Applications include process industries such as chemical, oil and gas, power, water treatment, and food and beverage, controlling temperature, pressure, level, and flow. Controllers connect to sensors and actuators and communicate over fieldbus, Ethernet, or wireless networks, often within larger automation architectures that include SCADA, PLCs, and DCS.