In certain applications, the current or voltage signal of a pressure transmitter must not exceed and/or drop below a critical value. This can be ensured using so-called signal limiting.
Why is a sign clamping necessary in the first place?
If the pressure on a pressure transmitter lies within the nominal pressure range, then there will be a defined signal output (e.g. 4 ? 20 mA or 0 ? 10 V). However, in technical applications, it frequently happens an originally planned pressure range is exceeded or is dropped below. This can happen deliberately, for example when cleaning, and also accidentally, for example through load variations or in case of a fault. In Failure , the sensor signal will also move outside the defined limits, so that, for example, a current signal in the range of 3.6 to 25 mA may appear.
If now, however, the evaluation electronics are set so they recognise a signal outside of the defined limits as an error, in a few situations, trouble-free operation of the entire system cannot be ensured anymore. In these cases, a signal limiting of the pressure transmitter makes sense, so the output signal is maintained within the mandatory range (e.g. 3.8 ? 21 mA).
Note
An example of a pressure transmitter with which the voltage signal as well as the current signal can be limited is the model S-20 (for general industrial applications) or the model MH-3 (for mobile working machines) from WIKA.