In certain applications, the existing or voltage signal of a pressure transmitter must not 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 you will see a defined signal output (e.g. 4 ? 20 mA or 0 ? 10 V). However, in technical applications, it frequently happens that an originally planned pressure range is exceeded or is dropped below. This can happen deliberately, for instance when cleaning, as well as accidentally, for example through load variations or in the event of a fault. In such cases, the sensor signal will also move beyond your defined limits, in order that, for example, an ongoing signal in the range of 3.6 to 25 mA can occur.
If now, however, Case Study are set so that they recognise a signal outside the defined limits as an error, in a few situations, trouble-free operation of the entire system can’t be ensured anymore. In such cases, a signal limiting of the pressure transmitter is practical, so that the output signal is maintained within the required range (e.g. 3.8 ? 21 mA).
Note
An 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.