BIFFI ICON-040 - Page 44

December 2019
36
Installation, Operation and Maintenance Manual
VCIOM-08500-EN
Operating the ICON3000
Section 5: Operating the ICON3000
If mains voltage is lost, behavior will be different if the power supply of the
4-20 mA output stage is internally- or externally-generated:
- Internal power supply (or passive loop):
If mains voltage is lost the output 4-20 mA drops to 0. The correct output
will be restored when mains voltage returns.
- External power supply (or active loop):
If the actuator is provided with a lithium battery (or supplied by the
auxiliary 24 V DC) and if mains voltage fails, the output 4-20 mA
maintains the last value. If the actuator is moved via the handwheel, the
output 4-20 mA will be updated.
If the actuator is not provided with a lithium battery
(or not supplied by the auxiliary 24 V DC) and mains
voltage fails, the output 4-20 mA maintains the last value.
If the actuator is moved by handwheel, the output 4-20 mA will not be
updated.
• 4-20 mA analog input
The 4-20 mA analog input is the position request R% signal and is used by
the ICON3000 to position the valve in positioning (inching) and modulating
actuators. The “POSITIONER” routine processes the input signal, compares the
present actuator position % with the position request R%, and if the difference
is greater than the dead band - the actuator is driven to reach the requested
position. 4 mA corresponds to request R% = 0% = valve closed and 20 mA
corresponds to request R% = 100% = valve open. The relationship between
position and request signals can be reversed by the “Polarity” function. The
4-20 mA input is optically-isolated (opto-coupled). The input impedance is less
than 500 ohm. The loss of the 4-20 mA input signal is indicated as follows:
- Change-over of the monitor relay
- Alarm LED on
- List of ALARMS (see Section 12.11, Diagnostic messages)
- Alarm log
Figure 43 shows the wiring diagram.
Figure 43
The “VIEW and SET-UP” features can congure different options, which are described in
Section 9.1.7, Positioner.
If the POSITIONER function is active, the alpha-numeric display indicates the value of the
position request in % (R%: xxx.x).
B9
B8
0 V DC
4-20 mA
0 V
Actuator terminals
Cable
GROUND
Shield
4-20 mA
generator
Figure B