EB 8389 EN
65
Tests
5.1.1 Analysis and monitoring
The following effects can be read by com-
paring the correlation between the drive sig-
nal and valve position measured during the
test and in the reference graph:
−
The drive signal runs below the reference
as the gradient rises.
−
The
drive signal
starts to rise steadily at a
certain valve opening compared to the
reference graph. This pinpoints to signifi
-
cant leakage in the pneumatics arising
due to screw fittings that are not tight
-
ened properly or due to a tear in the di-
aphragm. The positioner generates the
'Leakage pneumatics' message with the
selected status classification.
−
The drive signal initially follows the
course plotted in the reference graph and
then starts to rise almost steadily. This
pinpoints to a supply pressure that is in-
sufficient for the valve to move through
its entire working range. The positioner
generates the 'Air supply' message with
the selected status classification.
−
The drive signal shifts downwards with a
smaller gradient than in the reference
graph, pinpointing to a reduced spring
force in a fail-close control valve. The po-
sitioner generates the 'Actuator springs'
message with the selected status classifi
-
cation.
Diagnosis > Status messages > Extended
−
Air supply
−
Leakage pneumatics
−
Actuator springs
5.1.2 Resetting single status
messages
The diagnostic parameters and measured
data analysis from the 'Drive signal dia-
phragm steady-state' test are reset by select-
ing and executing the command "Reset
'Drive signal diagram steady-state measured
data'".
Operation > Reset
−
Reset 'Drive signal diagram steady-state mea-
sured data'
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