In certain applications, the current or voltage signal of a pressure transmitter should never exceed and/or drop below a critical value. This could be ensured with the aid of so-called signal limiting.
Why is a signal clamping necessary to begin with?
If the pressure on a pressure transmitter lies within the nominal pressure range, then there will be 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. Spunky can happen deliberately, for example when cleaning, and accidentally, for instance through load variations or in case of a fault. In such cases, the sensor signal will also move outside the defined limits, in order that, for example, a current signal in the number of 3.6 to 25 mA can occur.
If now, however, the evaluation electronics are set so they recognise a signal outside of the defined limits being an error, in a few situations, trouble-free operation of the complete system can’t be ensured anymore. In such cases, a signal limiting of the pressure transmitter makes sense, so 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 that your voltage signal as well as the current signal could be limited may be the model S-20 (for general industrial applications) or the model MH-3 (for mobile working machines) from WIKA.