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Statistical information
Based on the operating point, the test is per-
formed with a change in travel of less than
1 % to find the change in drive signal (∆y).
The changes in drive signal ∆y are classified
according to the valve position x in the valve
position classes. The average value ∆y per
valve position class is calculated from all the
values and plotted in a graph (Measure-
ment).
Note:
− If the test is started in manual mode
using the setting 'Enable time dis-
tance' = 'User defined' and anoth-
er test is active at the time select-
ed, the hysteresis test starts 30 sec-
onds after the active test ends.
− A straight line from the average
reference data is shown in cas-
es where no data could be com-
piled for valve working rang-
es which were not covered by
the long-term monitoring.
− If the hysteresis test could not be
completed because the valve po-
sition is at the top or bottom limit
of the working range, the position-
er indicates 'Test at operating point
not possible' (Test information).
Short-term monitoring
To provide a short-term trend, the last ten
valve positions x and the associated changes
in drive signal (∆y) values are saved in the
Short-term folder.
46
Requirements
1. A single-acting actuator is mounted on
the valve.
2. No booster is mounted on the control
valve.
3. The valve operates as a control valve.
4. A reference test has been performed.
See
Section 1.2.1.
u
Settings > Identification > Positioner >
Actuator
1.
− Model: Single acting, [-/-]
2. − Booster: Not present, [-/-]
Start-up
3.
− Application type (Code 49 - h0): Control
valve
Defining parameters
1. Select classification for status messages.
2. Set cancelation condition. See
3.7.1.
3. Define start conditions.
4. Start hysteresis test.
The 'Test information' status indicates
'Running test'. 'd5' and 'tEST' are indi-
cated in alternating sequence on the po-
sitioner display. 'Function check'
activated as the condensed state.
Settings > Positioner > Error control >
Classification report > Extended > ...
1.
Friction
− Much higher over whole range:
[
],
,
,
− Much lower over whole range: [
Section
u
is
],
,
,
EB 8389S EN
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