In certain applications, the existing or voltage signal of a pressure transmitter must not exceed and/or drop below a crucial value. This can be ensured using 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 have a defined signal output (e.g. 4 ? Brutal 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 instance when cleaning, and accidentally, for example through load variations or in the event of a fault. In such cases, the sensor signal may also move beyond your defined limits, in order 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 that they recognise a signal outside of the defined limits as an error, in some situations, trouble-free operation of the complete system can’t be ensured anymore. In these cases, a sign limiting of the pressure transmitter is practical, so the output signal is maintained within the mandatory range (e.g. 3.8 ? 21 mA).
Note
Attack 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.