Adjuster
The adjusters for adapting the reference vari-
able (input signal) and travel range are lo-
cated under the cover plate on the top side of
the actuator.
Zero
adjustment for initial value
of the reference variable
Jumper for
operating direction
Direct action >>
with increasing
control signal "actuator stem re-
tracts"
Reverse action <>
with increas-
ing control signal "actuator stem
extends"
Span
adjustment for the range
(final value) of the control signal
Valve adjustment
Connect the actuator’s input terminal to a cur-
rent or voltage source (or controller)
Example:
A valve should move from the closed position
to the opened position (travel 0 to 100 %)
with an input signal of 4 to 20 mA (see
Fig. 11 characteristic increasing-increas-
ing >>).
Presetting:
Adjust the connector for
direct operating di-
rection >>
, since the actuator stem must re-
tract with increasing current input so that the
valve can be opened.
Adjust the
zero adjuster
to 20 % (=4 mA) and
move
span adjuster
clockwise to a small
range.
If the input signal is zero, the plug stem of the
control valve must rest in the lower end posi-
tion, i.e. actuator stem must be extended until
it stops at the plug in the valve.
Adjustment
Starting point (zero)
Slowly increase input signal on the source.
The LED must illuminate above the zero ad-
juster at exactly 4 mA, indicating the run of
the actuator motor. The plug stem is released
from the lower end position.
A starting point which is too early or late can
be corrected by slightly adjusting the value
on the
zero adjuster
, decreasing input signal
to zero each time and waiting until the plug
stem rests in the lower end position, i.e., actu-
ator stem must be positioned until it stops.
Final value — span
Adjust input signal on the source to the
desired final value (20 mA).
0
100
25
50
75
Zero
Operating
direction
Span
Fig. 11
⋅
Increasing/decreasing charac-
teristic
Fig. 12
⋅
Split-range operation
(two valves operating in opposite
directions)
4
20 mA
Travel
>>
<>
Reference variable
Input signal
Actuator stem
retracted
Actuator stem
extended
4
20 mA
Travel
>>
<>
12
Dead band
Valve 2
Valve 1
Actuator stem
retracted
Actuator stem
extended
9
