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3.4.2 Adjusting the tolerance band
The value of the effective tolerance band depends upon the air capacity and the friction
of the actuator (control valve). The span is from 0.3 % to 10.0 % (referred to a movement
of 100 %). The smallest possible value is determined by Autostroke, checked while the
positioner is running in "adaptive" control mode, and corrected if required. If it is neces-
sary to improve stability, you can set higher values by manual data entry via the operator
panel. For details refer to the section about operating level 2, "Display 2.1 = Man. dead
band adjustment".
3.4.3 Adjusting the valve action
The positioner works with two types of valve action:
Direct:
Reverse:
The valve action can be adjusted on the operator panel as described below (factory set-
ting defaults to "direct action"):
Changing over from direct to reverse action
•
Call up operating level 2, display 2.0 = Autostroke.
•
Press and hold the "Down" push button.
•
Wait until the displayed countdown from 3 to 0 is finished, then release the "Down"
button.
•
Press and hold the "Down" button again.
•
Wait until the displayed countdown from 3 to 0 is finished, then release the "Down"
button.
The display shows the code "P31", which is flashing in the beginning and then changes
over to a permanent display. After another 2 seconds, it is replaced with a flashing colon.
Save the newly set parameters in the non-volatile memory as described in section "Exit-
ing operating level 2".
Changing over from reverse to direct action
The procedure is the same as described above. However, in this case you must press the
"Up" button instead of the "Down button". The code shown in the display is "P32" instead
of "P31".
3.4.4 Setting parameters for current operation
Normally, "Controlling adaptive" at operating level 1 is selected for current operation. It is
only necessary to select "Controlling fixed" if the positioner is working unstable in adap-
tive mode.
42/18-54 EN
Signal 4...20 mA, position 0...100 %
Signal 20...4 mA, position 0...100 %
Electro-pneumatic positioner TZID
27
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