Temperature indicators and controllers are used in a wide range of applications, often in control panels, to monitor and control temperature.

Temperature controllers measure the temperature using sensors and use the signal to control various actuators, such as heating or cooling elements. They can control different devices or processes depending on the application. These controllers often use PID (proportional-integral-derivative) algorithms to improve control accuracy, with each part of the algorithm playing a specific role in stabilisation and adjustment. By combining these components, temperature controllers enable precise control.

Two-point controllers operate with two states: on and off. Three-point controllers add a neutral intermediate state. In contrast, continuous controllers, which are designed to reach and maintain the setpoint quickly and accurately, operate with less overshoot. The basic types of continuous controllers are P, I and D controllers. The P controller quickly brings the actual value closer to the setpoint, but has a permanent control deviation that can be compensated for by combining it with an I controller. The I controller integrates the control deviation over time to compensate for it, but is slow. A PI controller combines these characteristics, but responds slowly to sudden changes. This is where the D controller comes in, quickly correcting even small deviations. Since a pure D controller does not recognise a constant deviation, it is combined with P or PI controllers to improve response time. A PID controller combines all three algorithms to respond quickly to both large and small control deviations and eliminate permanent deviations.