4. Operation
4.1 Manual operation of the actuator
(Type 5821 only)
If the release button (2) is actuated, the clutch
between the motor and the gear is disen-
gaged. In this state, the control valve can be
moved in the desired position by turning the
handwheel.
4.2 Adjusting the limit switches
(Fig. 9)
The limit switches can optionally be used as
double-throw, normally-closed or normally-
opened contacts.
The cam disks used to operate the limit swit-
ches can be adjusted after the cover plate
(1.3) has been moved out of place. Each
operating direction of the actuator ("actuator
stem retracts" or "actuator stem extends") is
assigned a separate cam disk. The desired
switching point (limit value) is obtained by
adjusting the appropriate cam disks.
Adjusting the direction of rotation causes
either an earlier switchover point or, in the
opposite direction, a later switching point.
4.3 Adjusting the potentiometer
To signalize the valve travel, the range of re-
sistance from 0 to 1000
Ω
is to be adjusted to
the valve travel. The closing position of the
valve is always important, as it is to be ad-
justed exactly as zero-point at 0 or 1000
Ω
.
For this purpose, fasten connecting terminals
to the appropriate multimeter or directly to
the position indicator of the controller as indi-
cated in the wiring diagram (Fig. 8). Move
through the travel range of the actuator and
adjust the potentiometer so that the resistance
value or indicator exactly correspond to the
final position. The potentiometer can be ad-
justing through the lateral opening (Fig. 10)
by shifting the soldering tags using a screw
driver.
4.4 Version with electric positioner (adjust-
ment)
In this version, the actuator is controlled by a
load-independent d.c. current or d.c. voltage
signal as reference variable (input signal).
The travel of a valve (0 to 100 %) must be as-
signed to this input, usually a control signal in
the range from 4 to 20 (0 to 20 mA) or 0 to
10 V.
In
split-range operation
, the control valves
require smaller reference variables (input sig-
nals). For this purpose, the controller output
signal for operating two control instruments is
divided in such a way that these pass through
their entire travel at half an input signal each
(e.g., first control valve adjusted to 4 to
12 mA and second control valve adjusted to
12 to 20 mA). In order to avoid overlapping
of the valves, a dead band of
±
0.5 mA must,
if applicable, be considered (see Fig. 11).
11
14
12
21
24
22
Switch S1
Switch S2
Retracting
Extending
Connecting terminal
1
2
Cam disk assigned
Direction of
rotation handwheel
Actuator stem
Soldering tag
Fig. 9
⋅
Limit switch
Fig. 10
⋅
Potentiometer
8
