8 ACE 71 en
11
The display is calibrated with the trimmer potentiometers
of display card (216), Fig. 15. Potentiometers are marked as
"SPAN" (R9) and "ZERO" (R14). When the valve is in the clos-
ing position and the current is 4 mA the display is adjusted
with ZERO-potentiometer to 00.0 %. Current value is meas-
ured from the pins 2 and 3 in connector X5 in connector
card. When the valve is in the open position the display
reading is adjusted with SPAN-potentiometer to 100.0 %.
If the display shows - % continuosly, the current loop is
open. This can be the case if NelesAce is tested on the
bench before connecting to DCS. In order to obtain the cor-
rect figures during the bench test connect a jumper
between pins 3 and 4 on connector X5 to complete the cir-
cuit. Remove the jumper when connecting to DCS.
6.3
Replacement and calibration of
potentiometer and R/I modulator
Move valve to CLOSE position.
Remove connector cover in actuator (143).
Unfasten gear cover screws (126), 6 pieces.
Disconnect modulator's (50) connections.
Unfasten potentiometer's locking screws.
Remove potentiometer and replace it with new one.
Measure resistance from the potentiometer and adjust it
to 50
Ω
by turning the potentiometer's shaft.
Tighten potentiometer's bracket (58).
Tighten potentiometer's locking screw (6).
Attach gear cover.
Measure current (4-20 mA) from connector X5 (2 and 3).
When valve is in CLOSE position, current is 4 mA
(potentiometer "4 mA" in R/I modulator).
When valve is in OPEN position, current is 20 mA
(potentiometer "20 mA" in R/I modulator).
Attach connector cover in actuator.
6.4
Removal and reinstallation of the
actuator
Actuator can be disengaged from the valve as follows:
Move valve to CLOSE position.
Switch off the power.
Remove finger covers (170) e.g. by prying with a
screwdriver from the gap between cover and
bracket.
Unfasten valve attachment bolts (173).
Unfasten shaft's locking screws (27).
Remove actuator carefully without causing damage.
Reinstalling is made in reverse order. Note, that valve and
actuator must be in CLOSE position before reinstallation.
While installing the valve check the gap between
segment and seat. The gap must be 0.20 mm in
every part of segment. If the segment has moved,
the gap may be smaller. In this case the segment
must be centred before tightening the locking
screws (27). Centring is made with a copper hammer
or with another soft tool so as not to cause damage
to the segment while hitting it. While the gap is of
equal size in every part of segment, locking screws
can be tightened.
Install finger covers (170) by pressing them back in
place. Check also the condition and stability of covers. If
the covers do not stay properly, adjust them by bend-
ing the bracket.
Never use the actuator without
properly mounted finger covers!
6.5
Trouble shooting
In the following charts, Fig. 16 and Fig. 17, some failure situ-
ations have been presented. The charts refer to label (228)
inside the controller and the LEDs of the controller, Fig. 5.
IPCOMM communication program and instructions file can
be also used in trouble shooting. The instructions file clari-
fies the functioning of application software. These charts
are only applicable to correctly mounted and connected
device. Installation and connection instructions are pre-
sented in Section 2.
6.6
Recommended preventive maintenance.
Recommended preventive maintenance for NelesAce, the
part list and the service actions, see table 6.
