In certain applications, the existing or voltage signal of a pressure transmitter should never exceed and/or drop below a critical value. Achieve can 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 an originally planned pressure range is exceeded or is dropped below. This may happen deliberately, for example when cleaning, together with accidentally, for instance through load variations or in the event 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 range 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 as an error, in a few situations, trouble-free operation of the entire system cannot be ensured anymore. In these cases, a signal limiting of the pressure transmitter makes sense, 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 and also 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.