Check if the valve begins to move at ex-
actly 20 mA.
Correct deviation using the zero adjust-
ment screw (4); turning it counterclock-
wise moves the control valve earlier from
its final position and clockwise later.
Upper range value (span)
e.g. 4 mA
3. After adjusting the starting point, adjust
the input signal to an upper range value
of 4 mA using the ammeter. With an up-
per range value of exactly 4 mA, the
plug stem must be motionless and there-
fore already moved through 100 % of its
travel range (watch the travel indicator at
the valve!).
4. If the upper range value is incorrect, the
pin (2) must be moved to correct the sig-
nal.
Adjust 20 mA and turn the zero adjust-
ment screw (4) until the required signal
pressure is indicated on the pressure
gauge.
By way of substitution for a pressure
gauge, set 19.5 mA as the starting point.
4.4 Exchanging the range spring
If the range is to be altered or changed to
split-range operation, replace the range
spring as shown in Fig. as follows:
1. Remove screw (7) on the range spring.
Pull out hexagon socket screw (5) and
the lever together with shaft.
2. Exchange range spring. Slide lever with
shaft through sleeve (3), positioner hous-
ing and bracket (6.1).
3. Secure range spring with the screw (7).
4. Move bracket and shaft until the screw
(5) sits on the flattened part of the shaft.
Tighten screw (5). Allow for a play from
0.05 to 0.15 mm between the lever (1)
and the sleeve (3) as well as between the
range spring (6) and the positioner
housing.
EB 8359-2 EN
17
Operation
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