Sensor technology

Principles of electronic pressure measurement

Pressure is a mechanical measurand. In order to process this in automation technology, it needs to be converted into an electrical signal. To do this, different physical effects are used which result from the deformability of different materials due to the pressure applied. There is a distinction between the following principles:

There is a distinction between the following principles:

  • Resistive measurement method – resistance change due to expansion or compression
  • Capacitive measurement method – capacitive change due to the plate distance
  • Inductive measurement method – inductive change due to the distance from a ferrite plate to the coil

JUMO. Production of pressure sensors

The sensing element, which converts the pressure into an electrical signal using one of the methods listed above, is generally referred to as a sensor or sensor element. The raw signal of the sensors is not yet suitable for processing in an evaluation unit, such as a controller or a PLC. It is too small and too prone to failure. It is also not usually linearly proportional to the pressure applied and is sensitive to temperature influences. The signal must therefore be processed by a subsequent electronics unit in order to be available at the output as a standard signal. Furthermore, the sensor requires a housing, an electrical connection, and a suitable process connection that can be used to mount it at the measuring point. It is only referred to as a pressure transmitter in this finished expansion stage.

Fig. 1 Sectional view of OEM pressure transmitter JUMO MIDAS SI