Samson 3730-3 ESD - Notes on applications

4 Notes on applications
Usually, shut-off valves in a safety-instru
-
mented system are equipped with a solenoid
valve for emergency shutdown.
Several setups are possible when integrating
the Type 3730-3 Positioner in ESD version
into the automation system:
In Fig. 3, the positioner replaces the sole-
noid valve.
The safety function is triggered by the
safety-related control; accordingly, the sole-
noid valve and the limit switch are con-
nected to it.
To read the additional diagnostic
information and define set points, it is advis-
able to integrate the positioner into the con-
trol system and the asset management sys-
tem.
As shown in Fig. 4, no solenoid valve is re
-
quired since the positioner, similar to the so
-
lenoid valve, is certified for safe shutdown.
When the energy supply fails, the pneumatic
output is safely vented.
In this setup, the positioner’s 4 to 20 mA
signal is applied to the safety-related pro
-
grammable logic controller. The HART
®
pro
-
tocol is used for connection to the asset
management system.
20 EB 8388-1 EN
Notes on applications
HART®
P
82
PT
1A
OUT OUTIN
81
42
12
4–20 mA 4–20 mA24 Volt
11
41
Fig. 3 · Positioner replaces solenoid valve
Tank
Safety-related
control
Control system
HART®
HART®
P
PT
1A
OUTIN
42
12
4–20 mA 4–20 mA
11
41
Fig. 4 · Positioner for emergency shutdown
Control system
Tank
Safety-related
control