EB 8389 EN
67
Tests
5.2 Drive signal diagram
hysteresis
3730-2 3730-3 3731-3 3730-4 3730-5 3731-5
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The 'Drive signal diagram hysteresis' (Tests)
allows you to check the results of the drive
signal diagram hysteresis in Statistical infor-
mation (in-service monitoring) more closely
(see section 4.7). Changes in friction can be
detected.
The test is started in the manual mode.
During the test the valve moves to various
fixed valve positions distributed over the
working range of the valve. After moving to
each valve position, a ramp movement
changing the valve travel by less than 1 % is
performed. The change in
drive signal (∆y)
is measured for each valve position x and
compared with the reference data. The re-
corded data of the change in
drive signal
(∆y)
are plotted versus the
valve position x
in
a graph.
Requirements
1. A single-acting actuator is mounted on
the valve.
2. No booster is mounted on the control
valve.
3. A reference test has been performed (see
section 2.4.1).
If a reference test has not be stored in the
positioner, the data of the first test per
-
formed are used as the reference.
Fig. 10:
Diagnosis > Tests > Drive signal diagram hysteresis
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