PT900-12 Monitor/Controller
Rev 2.0
20
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 PT900-12FG 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.
