Samson 4785, Монтаж и эксплуатация

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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 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 closed position. Now,
the zero point lever can be operated.
4.4.2 Initialization
After the electric reference variable and the
auxiliary supply pressure have been con-
nected to the positioner, the initialization
routine 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 routine 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 valve and actuator data 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
section 4.1).
Carry out the configuration suitable for
the valve type.
The following setting is recommended:
Fail-safe position "Actuator stem ex-
tends":
Operating direction: 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":
Operating direction: 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).
34
EB 8382-2 EN
Operation