Samson 3730-0 - Design and Principle of Operation

12 EB 8384-0 EN
Design and principle of operation
3 Design and principle of oper-
ation
Î RefertoFig.1
The electropneumatic positioner is mounted
on pneumatic control valves and is used to
assign the valve position (controlled variable
x) to the control signal (set point w). The po-
sitioner compares the electric control signal
of a control system to the travel of the control
valve and issues a signal pressure (output
variabley)forthepneumaticactuator.
Asupplypressurebetween1.4to6baris
required. The electric input signal is a set
pointbetween4to20mA.
The positioner is designed depending on
which accessories are selected either for
directattachmenttoSAMSONType3277
Actuators or for attachment to actuators
accordingtoNAMUR(IEC60534-6).
The positioner consists of a travel sensor
system proportional to resistance, an analog
i/p converter with a downstream air
capacity booster and the electronics with
microcontroller.
2
3
6
7
8
10
1
9
4
w
x
Q
y
x
1 Control valve
2 Travel sensor
3 PD controller
4 DIP switches
6 i/p converter
7 Air capacity booster
8 Pressure regulator
9 Flow regulator
10 Volume restriction
Fig.1: Functional diagram