Power A Positioner - Emerson AMS Trex User Manual

4.8

Power a positioner

If you try to apply power from the Trex unit when the device is externally-powered, the
Loop Diagnostics application prevents the Trex unit from supplying power. This protects
the Trex unit from damage.
CAUTION!
Remove the USB cable from the Trex unit before connecting to a device.
CAUTION!
Do not add any external power to the device when the Trex unit is powering the device. This
can blow a fuse inside the Trex unit. The repair/replacement will need to be completed at an
authorized service center. Ensure the device is disconnected from the loop/segment and no
other wires are connected to the device before providing power from the Trex unit.
Procedure
1.
2.
3.
4.
User Guide
Connect the lead set to the HART + pwr terminals on the Trex unit and to the
positioner.
Figure 4-16: Connection for powering a positioner
On the Loop Diagnostics screen, tap Trex Unit Power.
Select one of the following:
Option
Power Positioner with 4 mA (0%)
Power Positioner with 20 mA (100%)
Power Positioner with other mA value
Tap OK.
Loop Diagnostics application
Description
Power a positioner using 4 mA.
Power a positioner using 20 mA.
Power a positioner using a specified mA
value.
139