In certain applications, the current 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 there will be 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. This may happen deliberately, for example when cleaning, and accidentally, for example through load variations or in case of a fault. In such cases, the sensor signal will also move beyond your defined limits, so that, for example, an ongoing signal in the number 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 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 is practical, so the output signal is maintained within the required range (e.g. 3.8 ? 21 mA).
Note
เกจวัดความดันแก๊ส of a pressure transmitter with that your 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.