In certain applications, the existing or voltage signal of a pressure transmitter should never exceed and/or drop below a critical value. This is often ensured using so-called signal limiting.
Why is a signal clamping necessary in the first place?
If the pressure on a pressure transmitter lies within the nominal pressure range, then you will see a precise signal output (e.g. 4 ? 20 mA or 0 ? 10 V). However, in technical applications, it frequently happens that an originally planned pressure range is exceeded or is dropped below. This can happen deliberately, for instance when cleaning, and accidentally, for example through load variations or in case of a fault. In these cases, the sensor signal will also move outside the defined limits, so that, for example, a current signal in the number of 3.6 to 25 mA may appear.
If now, however, the evaluation electronics are set so they recognise a signal outside the defined limits as an error, in a few situations, trouble-free operation of the entire system can’t be ensured anymore. In such cases, a sign limiting of the pressure transmitter makes sense, in order that the output signal is maintained within the mandatory range (e.g. 3.8 ? 21 mA).
Note
Embarrassing of a pressure transmitter with which the voltage signal plus the current signal can be limited may be the model S-20 (for general industrial applications) or the model MH-3 (for mobile working machines) from WIKA.