22
Malfunction Condition
The malfunction alarm is activated when the 4-20ma analog output from the
sensor transmitter falls below 2.0mA. This is caused if the sensor requires
calibration. The malfunction also occurs if wires connecting the sensors are
broken. The fault relay is always non-latching and has a common alarm
contact on the PT900-12R termination board. The relay however, can be
programmed as normally open or normally closed.
If a fault condition occurs:
1.
Make sure the wires on the sensor input terminal of the main connection
board are secure and connected properly.
2.
Check if the sensor supply fuse located on the control module is OK. The
fuse can be checked by verifying the DC power on the sensor terminal
using a digital voltmeter. If the + and - pin on the sensor terminal reads
24VDC then the fuse is OK. See figure 6 for the location of the fuse on the
control module.
3.
Refer to the reference manual of the remote sensor for the problems the
sensor transmitter may have.
