Pressure Change; Method Of Measurement - Festo MSE6-E2M Original Instructions Manual

5 Measurement and control functions
5.4

Pressure change

5.4.1

Method of measurement

The pressure change DP2 is determined cyclically at intervals, the settable pressure change sample
time DT. To determine the differential pressure, the difference between the current measured pressure
value and the measured pressure value P2, based on the pressure change sample time, is calculated:
DP2 = P2(t) - P2(t-DT); t = Current measuring time.
The start of the measuring cycle to determine the pressure change is automatically synchronised with
the activation signal of the shut-off valve. The current pressure change value DP2 remains constant up
to the next measuring time.
In the blocking state, the amount of the pressure change value is compared to the upper pressure
change limit value DP2_OGR and monitored for violation of the limit value. If limit value diagnostics are
activated, a diagnostic message is generated when:
ABS(DP2) , DP2_OGR.
DT synchronisation and DP2 OGR limit monitoring
The following time diagrams show the DT synchronisation and DP2 OGR limit monitoring (è Fig. 5.4).
1
Sample pressure curve with switching of the valve from the pressurised to the blocking state.
2 Curve of the pressure change signal resulting from 1.
3 Amount derived from 2 with a sample limit value violation at the start of the blocking state.
4
Time interval in which, when a diagnostic message is activated, a DP2 OGR limit value violation is
signalled.
54 Festo – MSE6-E2M-SY-EN – 1703d – English