October 2019
Installation, Operation and Maintenance Manual
MAN-02-04-97-0713-EN Rev. 1
36
Operating the XTE3000
Section 5: Operating the XTE3000
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
XTE3000 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
B9
B8
0 V DC
4-20 mA
0 V
Actuator terminals
Cable
GROUND
Shield
4-20 mA
generator
Figure B
