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 with the aid of so-called signal limiting.
Why is Pluck clamping necessary to begin with?
If the pressure 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 can happen deliberately, for example when cleaning, as well as accidentally, for instance through load variations or in the event of a fault. In these cases, the sensor signal will also move outside the defined limits, so that, for example, a current 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 the defined limits as an error, in some situations, trouble-free operation of the entire system cannot be ensured anymore. In Disempowered , a sign limiting of the pressure transmitter makes sense, 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 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.