Safety Function (Sil); Valve Diagnostics - Samson Series 3730 Mounting And Operating Instructions

Design and principle of operation

3.1 Safety function (SIL)

The safety function is based on the shutdown
of the i/p converter (6). This causes the
pneumatic actuator to be vented and the
valve to move to its fail-safe position.
Monitoring of the input signal
The i/p converter is switched off when the
input signal of the positioner at terminals
+11/–12 falls below 3.8 mA or 4.4 mA de-
pending on the positioner version (a signal
range of 4 to 20 mA is required). See
Fig. 20 on page 60.
Monitoring the voltage supply
(version with forced venting and solenoid
valve
The i/p converter and the solenoid valve
(when installed) are shut down whenever the
voltage at terminals +81/–82 falls below
12 V (an input voltage of 24 V DC is re-
quired). See Fig. 20 on page 60.
When the i/p converter is switched off as
part of the monitoring of the input signal or
the voltage supply, the fail-safe position S is
activated and is indicated on the positioner
display.
If required, the user can check the safety
function using the software.
Details on EXPERTplus Valve Diagnostics in
the Operating Instructions
12
EB 8389-1.
u

3.2 Valve diagnostics

The EXPERTplus valve diagnostics are inte-
grated into the positioner. They provide in-
formation on the control valve and generate
status messages, which allow faults to be
pinpointed quickly.
Details on EXPERTplus Valve Diagnostics in
the Operating Instructions EB 8389-1.
u
EB 8384-6 EN