Basic principles of RTD technology

General term: "device" This chapter is used in the documentation of several Beckhoff products. It is therefore written in general terms and uses the generic term "device" for the different device types such as terminal (EL/ELM/KL/ES series...), box (IP/EP/EPP series...), module (EJ/FM series…).

Resistance sensors, also called resistance thermometers or RTD sensors (Resistance Temperature Detector), are electrical components that change their electrical resistance due to their material temperature. Due to this effect, RTD sensors provide a very reliable and accurate temperature measurement and are used in many different applications as part of a temperature measurement. RTD sensors are passive components as they have no amplifier effect or control function and measure temperature via an absolute temperature measurement.

The change in the resistance value as a function of temperature is described for each sensor by a material-dependent, non-linear characteristic or curve. The measured resistance value is subsequently converted into a temperature via such characteristic curves. This can be done either by automatic processing or manual conversion.