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SYSTEM DESCRIPTION
Operating as a positioner
The actual position (POS) of the pneumatic actuator is measured via the position sensing system. The
controller compares this actual value of the position with the setpoint (CMD) , which can be specified as
a standard signal. If a control difference (Xd1) exists, a pulse-width modulated voltage signal is sent to
the positioning system as the correcting variable. With single-acting actuators, if the difference is positi-
ve, the pressurizing valve is driven via output B1; if it is negative, the exhaust valve is driven via output
E1. In this way, the position of the actuator is altered until the control difference is zero. Z1 represents a
disturbance.
Positioning
system Sole-
noid
Continious valve
Wegmeßsystem
Position setpoint Positioner
Position control
loop
Valve opening
CMD
POS
Xd1
B1
E1
P
K
Z1
Position sensor
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