Samson TROVIS 3730-3, Mounting And Operating Instructions

Page: 17 / 180

EB 8384-3 EN 17
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 vari-
able x) to the control signal (set point w). The
electric signal from a controlling system is
compared to the travel or the rotational angle
of the control valve and a signal pressure
(output variable y) is produced for the actua-
tor.
The positioner consists of a travel sensor sys-
tem (2) proportional to resistance, an analog
i/p converter with a downstream air capacity
booster (7) and the electronics with microcon-
troller (5).
The positioner is fitted with three binary con -
tacts as standard: A fault alarm output indi-
cates a fault to the control room and two con-
figurable software limit switches are used to
indicate the end positions of the valve.
1 Control valve
2 Travel sensor
3 PD controller
4 A/D converter
5 Microcontroller
6 i/p converter
7 Air capacity booster
8 Pressure regulator
9 Flow regulator
10 Volume restriction
11* Inductive limit switch
12* Solenoid valve
13* Analog position transmitter
14 Software limit switch, alarm
1/2
15 Fault alarm output, alarm 3
16 Display
17* Actuation of solenoid valve
18* Electrical insulation
19
D/A converter
20 Communication interface
21 HART
®
connection
22 Binary input BE*
*
Option
w
x
Q
%
S
mm
G G
PD
Serial
Interface
16
13
22
15
A2
A3
BE
A1
11
2
4
21
FSK
20
19
5
3
12
6
7
8
10
1
14
14
w
x
y
24 V DC
9
17
18
Fig. 1: Block diagram