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 to begin with?
If Perfect 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 that an originally planned pressure range is exceeded or is dropped below. This can happen deliberately, for example when cleaning, and accidentally, for instance through load variations or in the event of a fault. In such cases, the sensor signal may also move outside the defined limits, so that, for example, a current signal in the range of 3.6 to 25 mA can occur.
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 complete system can’t be ensured anymore. In these cases, a signal limiting of the pressure transmitter makes sense, in order that the output signal is maintained within the required range (e.g. 3.8 ? 21 mA).
Note
A good example of a pressure transmitter with which the voltage signal and also 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.