In certain applications, the existing or voltage signal of a pressure transmitter should never exceed and/or drop below a crucial value. This could be ensured with the aid of so-called signal limiting.
Why is a sign clamping necessary to begin with?
If the pressure on a pressure transmitter lies within the nominal pressure range, then you will see 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. Hoak can happen deliberately, for instance when cleaning, and also accidentally, for example through load variations or in the event of a fault. In these cases, the sensor signal will also move beyond your defined limits, so that, for example, an ongoing signal in the range of 3.6 to 25 mA may appear.
If now, however, the evaluation electronics are set so that they recognise a signal outside of the defined limits being an error, in a few situations, trouble-free operation of the entire system can’t be ensured anymore. In these cases, a sign limiting of the pressure transmitter is practical, so that the output signal is maintained within the mandatory range (e.g. 3.8 ? 21 mA).
Note
A good example of a pressure transmitter with which the voltage signal plus the current signal could be limited is the model S-20 (for general industrial applications) or the model MH-3 (for mobile working machines) from WIKA.