In certain applications, the existing or voltage signal of a pressure transmitter must not exceed and/or drop below a crucial value. This is often ensured using so-called signal limiting.
Why is a signal clamping necessary to begin with?
If pressure gauge octa on a pressure transmitter lies within the nominal pressure range, then you will have a precise 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, together with accidentally, for example 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, an ongoing signal in the number of 3.6 to 25 mA may appear.
If now, however, the evaluation electronics are set so they recognise a signal outside of the defined limits as an error, in a few situations, trouble-free operation of the entire 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 plus 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.