Operating instructions

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. 18 on page 48.
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. 18 on page 48.
When the i/p converter is switched off by
the monitoring of the input signal or the volt
-
age supply, the fail-safe position
S is acti
-
vated and is indicated on the positioner
display.
If required, the user can check the safety
function using the software.
For more details, refer to the Operating In
-
structions EB 8389-1 EN on EXPERTplus
Valve Diagnostics.
3.2 Valve diagnostics
The EXPERTplus valve diagnostics are inte
-
grated into the positioner. They provide in
-
formation on the valve condition (see Ta
-
ble 1) and generate status messages to
quickly pinpoint faults.
For more details, refer to the Operating In
-
structions EB 8389-1 EN on EXPERTplus
Valve Diagnostics.
3.3 Flow rate calculation
Due to the differential pressure measurement
D
p out, EXPERTplus is able to calculate the
flow rate in a SAMSON Type 3241 or
Type 3251 Valve, provided all the parame-
ters regarding the medium and the process
have been defined in the positioner.
For more details, refer to the Operating In-
structions EB 8389-1 EN on EXPERTplus
Valve Diagnostics.
10 EB 8384-6 EN
Design and principle of operation