Samson TROVIS 3730-3, Руководство по эксплуатации

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70 EB 8389 EN
Tests
5.3 Static characteristic
3730-2 3730-3 3731-3 3730-4 3730-5 3731-5
• • • • • •
The static performance of the control valve is
affected by the friction hysteresis and the
elastic processes in the valve stem packing.
The test is started in the manual mode.
The positioner specifies the set point w in a
defined test range ('Start' and 'End') in small
steps and records the response of the valve
position x after waiting a 'Delay time after
step'. The step height is determined automat-
ically from the number of measured values
('No. until reversing') and the defined test
range. The ascendent and descendent are
plotted within the test range. The response of
the valve position x to the change in set point
(∆w) is plotted in a graph.
The dead band is analyzed in the positioner
when a step height is smaller than 0.2 %.
− 'Min. dead band': Minimum change in
set point that causes a minimal change
in the valve position.
−
'Average dead band': Average change
in set point that causes a minimal change
in the valve position.
− 'Max. dead band': Maximum change in
set point that causes a minimal change
in the valve position.
The difference in set point w that causes a
minimal change in the valve position x is
termed ‘dead band’.
Defining parameters
1. Switch to manual mode.
Fig. 11: Diagnosis > Tests > Static characteristic