Samson TROVIS SAFE 3730-6, Монтаж и эксплуатация, Страница: 17 / 184

EB 8384-6S EN 17
Design and principle of operation
3 Design and principle of oper-
ation
Î
See Fig. 1
The electropneumatic positioner is mounted
on pneumatic control valves and used to
assign the valve position (controlled variable
x) to the control signal (set point w). The
positioner compares the electric control
signal of a control system to the travel or
opening angle of the control valve and issues
a signal pressure (output variable y) for the
pneumatic actuator.
The positioner consists of a travel sensor
system (2) proportional to resistance, an
analog i/p converter (6) with a downstream
air booster (7) and the electronics with
microcontroller (5).
PD
FSK
%
S
mm
%
mm
w
x
Q
G G
Serial
Interface
16
13
22
15
A2
A3
BE
A1
11
2
4
21
20
19
5
3
12 25
6
7
23
8
10
1
14
14
w
x
y
24 V DC
9
17 18
x
1)
>12 V
&
24
x
1)
Depending on version >3.8 mA or >4.4 mA
1 Control valve
2 Travel sensor
3 PD controller
4 A/D converter
5 Microcontroller
6 i/p converter
7 Air booster
8 Pressure regulator
9 Flow regulator
10 Volume restriction
11* Inductive limit switch
12* Solenoid valve
13* Analog position transmitter
or binary input
14 Software limit switch A1/
A2
15 Fault alarm output A3
16 LCD
17* Actuation of solenoid valve
18 Galvanic isolation
19
D/A converter
20 Communication interface
21
HART ® connection
22* Binary input BI
23 Pressure sensor for supply
air p
s
24 Pressure sensor for signal
pressure p
out
25* Forced venting
* Option
Fig. 1: Block diagram