Samson 3731-3 - Additional Equipment

software or on site at the positioner. A con
-
stant air stream to the atmosphere is created
by the flow regulator (9) with a fixed set
point. The air stream is used to purge the in
-
side of the housing as well as to optimize
the air capacity booster (7). The i/p con
-
verter (6) is supplied with a constant up
-
stream pressure by the pressure regulator
(8) to make it independent of the supply
pressure.
All parts are enclosed in an Ex d housing.
The electrical wires are connected over a
separate terminal compartment which is also
designed with Ex d protection.
The extended EXPERTplus diagnostics are in
-
tegrated into the positioner. It provides infor
-
mation on the positioner and generates di-
agnostic and status messages, which allow
faults to be pinpointed quickly.
The positioner is suitable for the following
types of attachment using the corresponding
accessories:
4
Direct attachment to SAMSON
Type 3277 Actuator: section 4.1
4
Attachment to actuators acc. to
IEC 60534-6 (NAMUR): section 4.2
4
Attachment to Type 3510 Micro-flow
Valve: section 4.3
4
Attachment to rotary actuators acc. to
VDI/VDE 3845: section 4.4
3.1 Additional equipment
Forced venting
The i/p converter stops working if the oper
-
ating voltage supply to the relevant terminals
is interrupted. The positioner can no longer
operate and the control valve moves to the
fail-safe position (SAFE) determined by the
actuator, independent of the reference vari
-
able.
Binary contact
The positioner has three internal binary sig
-
nals which can be analyzed over terminals
A/B/C. Two of these signals are intended
for the valve end positions and one signal
for a collective fault alarm. The assignment
of these signals to the A/B/C terminals is
determined over Code 25.
Position transmitter
The position transmitter (13) is a two-wire
transmitter and issues the travel sensor sig-
nal as a 4 to 20 mA signal processed by the
microcontroller. Since this signal is issued in
-
dependent of the positioner’s input signal
(min. current 3.8 mA), the actual travel/an
-
gle of rotation is controlled in real-time. Ad
-
ditionally, the position transmitter provides
the possibility of signaling a positioner fault
over a signal current of 2.4 mA or
21.6 mA.
Binary input
The positioner has an optional binary input.
The following actions can be performed over
the binary input:
EB 8387-3 EN 9
Design and principle of operation