Samson 3780 series, Mounting And Operating Instructions

Page: 35 / 76

4.3 Default setting
All parameters are set to default values. See
section 8 for a description of parameters.
Note!
Manual operation and activated
final position functions can cause
the actuator to be filled with the
maximum supply pressure.
Should this lead to impermissible
forces occurring, the supply pressure
must be restricted by a reducing sta-
tion.
4.3.1 Adjusting mechanical zero
point
Note!
Zero must be adjusted with the valve com-
pletely closed (for three-way valves with the
actuator stem extended).
Firmly push the zero point lever, which
is located in the cover plate of the posi-
tioner, once in the direction indicated
by the arrow, as far as it will go. The
yellow pointer will then be on the white
marking line.
For control valves with the starting position
OPEN, e.g. an actuator employing fail-safe
action "actuator stem retracts", it is first
necessary to supply the positioner with aux-
iliary air.
If the manual operation function is activated
then, the signal pressure builds up and the
valve moves to the closed position. Sub-
sequently, the zero point lever can be oper-
ated.
4.3.2 Initialization
After the electric reference variable and the
auxiliary supply pressure have been con-
nected to the positioner, the initialization
process can be started. In this process, the
positioner adapts itself optimally to the
mechanical conditions (friction) and signal
pressure requirements of the control valve.
See list of parameters on page 48 for re-
quired changes of the proportional-action
coefficient KP_Y1 and KP_Y2.
Caution!
The initialization process takes sev-
eral minutes. During that time the
valve leaves its position. Therefore,
never initialize the positioner during
a running process, but only during
the start-up cycle when the shut-off
valves in the plant are closed, or
when the control valve with the posi-
tioner has been removed from the
plant and is used on a test stand.
Enter data on valve and actuator under
"Start-up" in the operating software.
Set "Type of initialization" to "Rated
range", select "Maximum range" only
for three-way valves.
Start initialization.
When the initialization process is com-
pleted, perform configuration suitable
for the type of valve.
The following setting is recommended:
EB 8380-1 EN
35
Operation
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