Samson 373 Series Operating Instructions

EB 8389 EN 51
Statistical information
4.6.1 Analysis and monitoring
Analysis of the drive signal for control
valves starts one hour after the observation
period begins. No analysis is performed for
on/off valves.
The following effects can be read by com-
paring the correlation between the drive sig-
nal and valve position measured during op-
eration 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 signi-
cant leakage in the pneumatics arising
due to screw ttings 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 classication.
− 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-
sufcient for the valve to move through
its entire working range. The positioner
generates the 'Air supply' message with
the selected status classication.
− 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 classi-
cation.
Diagnosis > Status messages > Extended
− Air supply
− Leakage pneumatics
− Actuator springs
The results from the Statistical information
test can be checked by performing a test
from Tests (out-of-service diagnostics) if the
process allows it. See section5.1.
4.6.2 Resetting single status
messages
The messages 'Air supply', 'Leakage pneu-
matics' and 'Actuator springs' are reset by
the command "Reset 'Drive signal diagram
steady-state'" or "Reset 'Drive signal dia-
gram steady-state - short-term'".
By selecting and executing the command
"Reset 'Drive signal diagram steady-state'",
all the measured data of the diagram, in-
cluding the short-term monitoring, are reset.
By selecting and executing the command
"Reset 'Drive signal diagram steady-state -
short-term'", the measured data in the
'Short-term' folder are reset.
Operation > Reset
− Reset 'Drive signal diagram steady-state'
− Reset 'Drive signal diagram steady-state -
short-term'
Note

Samson 373 Series Specifications

General

Brand	Samson
Model	373 Series
Category	Valve Positioners
Language	English