19
Type 8692, 8693
english
Description of System
3 TYPE 8692 POSITIONER WITH POSITION CONTROLLER
The position measuring system records the current position (POS) of the pneumatic actuator. The position controller compares
this actual position value with the set-point value (CMD), which is definable as norm signal. In case of a control deviation (Xd1),
a pulse-width modulated voltage signal is sent to the control system as a manipulated variable. If there is a positive control dif-
ference in single-acting actuators, the air inlet valve is controlled via output B1. If the control difference is negative, the bleed
valve is controlled via output E1. In this way the position of the actuator is changed until control difference is 0. Z1 represents
a disturbance variable.
Valve opening
Continuous
valve
Control system
solenoid valves
Position measuring
PositionerPosition set-point
value
CMD Xd1
B1
E1
P
K
Z1
POS
Position control circuit
+
-
Fig. 4: Signal flow plan of position controller
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