Burkert Type 8791 - Manual (Page 17)

17
Function
7.2. function of the position control
The position sensor 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 a standard signal. If there is a control difference
(Xd1), the actuator is aerated and deaerated via the control system. In this way the position of the actuator is changed
until control difference is 0. Z1 represents a disturbance variable.
Valve opening
Control valve Control system
Solenoid valves
Position sensor
Position
controller Position set-
point value
CMD Xd1
B1
E1
P
K
Z1
POS
Position control circuit
+ -
Figure 3: Signal flow plan of position controller
english
Type 8791