4.4.1 Adjusting mechanical zero
NOTE
Zero must be adjusted with the valve 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 mark-
ing 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 auxi-
liary air.
As soon as the manual operation function is
activated, the signal pressure builds up and
the valve moves to the closed position. Sub-
sequently, the zero point lever can be oper-
ated.
4.4.2 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 fric-
tion conditions and signal pressure require-
ments of the control valve.
CAUTION
The initialization process takes sev-
eral minutes. During that time, the
valve changes its position. There-
fore, 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 positioner 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.
A successful initialization is indicated in the
operating software and over the LEDs (see
chapter 4.1).
Carry out the configuration suitable for
the valve type.
The following setting is recommended:
Fail-safe position "Actuator stem ex-
tends":
Direction of action: increasing/increas-
ing (>>), the globe valve opens with in-
creasing reference variable
Final position at a reference variable
less than 1% (tight closing),
Final position at a reference variable
larger than 125 % (function deactivated).
Fail-safe position "Actuator stem re-
tracts":
Direction of action: increasing/decreas-
ing (<>), the globe valve closes with in-
creasing reference variable
Final position at a reference variable
less than
−
2.5% (function deactivated),
Final position at a reference variable
larger than 99 % (tight closing).
32
EB 8382-1 EN
Operation
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