Samson 3730-4, Оригинальное руководство пользователя

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EB 8384-4 EN 9
Design and principle of operation
3 Design and principle of oper-
ation
The positioner is mounted on pneumatic con-
trol valves and is used to assign the valve
position (
controlled variable x) to the control
signal ( set point w). The positioner compares
the control signal of a control system to the
travel or rotational angle of the control valve
and issues a signal pressure (output vari-
able y) for the pneumatic actuator.
The positioner mainly consists of an electric
travel sensor system, an analog i/p convert -
er with a downstream air capacity booster
and the electronics with the microcontroller.
When a system deviation occurs, the actua -
tor is either vented or filled with air. If neces -
sary, the signal pressure change can be
slowed down by a volume restriction. The
signal pressure supplied to the actuator can
be limited by software or on site to 1.4, 2.4
or 3.7 bar.
The fixed flow regulator ensures a constant
air flow to the atmosphere, which is used to
flush the inside of the positioner housing and
to optimize the air capacity booster. The i/p
converter is supplied with a constant up-
stream pressure by the pressure regulator to
compensate for any fluctuations in the supply
pressure.
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 regulators
9 Flow regulator
10 Volume restriction
11* Inductive limit switch
12* Solenoid valve
13
IEC 61158-2 interface
module
14 Binary input BI1
(voltage input)
15* Binary input BI2
(for floating contact)
16 Display
17* Actuation of solenoid valve
18 Electrical insulation
19 D/A converter
20 Serial interface
* Options
w
x
Q
%
S
mm
G G
PD
Serial
Interface
16
15
BE2
BE1
11
2
4
13
20
17 18
19
24V DC
5
3
12
6
7
8
10
1
14
9
x
y
Fig. 1: Functional diagram