How does an active or passive temperature compensation of pressure transmitters really work? High-quality pressure transmitters, especially those used in precision critical applications, are almost always provided with an individual temperature compensation. But what’s actually the difference between an active and a passive temperature compensation of the sensors?
Passive temperature compensation: Sections of the characteristic accuracy curve of the pressure sensor are measured at different temperatures through the manufacturing process. Then, the previously determined temperature errors are compensated by passive elements (resistors) within the electronics of the sensor or by corrections of specifically designed resistance structures on the sensor element itself (e.g. by laser-trimming). The (passive) resistor elements used have an almost linear temperature behavior, it really is, however, only possible to pay 1st order errors. Temperature errors of higher order, i.e. strong bending of the characteristic curve under temperature, can not be compensated.
Active temperature compensation: Here too, the characteristic curve of the pressure transmitters is measured at different temperatures through the manufacturing process. However, the pressure transmitter comes with an additional integrated temperature sensor which constantly measures the temperature of the sensor and transfers it to the pressure transmitter?s signal processing. In practice, two ways of active temperature compensation are normal: the initial method compensates through a limited amount of samples, , i.e. discrete correction values, between which interpolation occurs.
The next method uses the electronics of the transmitter and a higher-order equation resulting from the regression of the acquired measurement values to be able to compensate then the expected error. During operation, this signal processing makes it possible to automatically, i.e. ?actively?, compensate the pressure transmitter ?s temperature error using the calculated correction factors within a specified temperature range (e.g. 10-60�C). The most commonly used solution to minimize temperature errors of pressure sensors is a passive temperature compensation. It is the traditional method that is widely used.
However, active temperature compensation may be the top class of possible compensation methods. WIKA has constantly improved and refined this technology in recent years. Sly of WIKA using active temperature compensation therefore feature a temperature error which is almost zero in their specified temperature range.