Hydronix Hydro-Probe XT, Руководство пользователя

Страница: 55 / 67

Sensor diagnostics Chapter 7
Hydro-Probe XT User Guide HD0538 Rev: 1.6.0 55
1.4
Symptom: Near constant moisture reading
Possible
explanation
Check Required result Action required on
failure
Empty bin or sensor
uncovered
Sensor is covered by
material
100mm minimum
depth of material
Fill the bin
Material ‘hanging up’
in bin
Material is not hanging
up above sensor
A smooth flow of
material over the
face of the sensor
when the gate is
open
Look for causes of
erratic flow of
material. Reposition
sensor if problem
continues
Build-up of material
on sensor face
Signs of build-up such as
dried solid deposit on
ceramic face
Ceramic faceplate
should be kept
clean by the
action of material
flow
Check angle of the
ceramic in range of
30° to 60°.
Reposition sensor if
problem continues
Incorrect input
calibration within
control system
Control system input
range
Control system
accepts output
range of sensor
Modify control
system, or
reconfigure sensor
Sensor in alarm
condition – 0mA on
4-20mA range
Moisture content of
material by oven drying
Must be within
working range of
sensor
Adjust sensor range
and/or calibration
Interference from
mobile phones
Use of mobile phones
close to sensor
No RF sources
operating near to
sensor
Prevent use within
5m of sensor
Average/Hold switch
has not operated
Apply signal to digital
input
Average moisture
reading should
change
Verify with Hydro-
Com diagnostics
No power to sensor DC power at junction box +15Vdc to
+30Vdc
Locate fault in power
supply/ wiring
No sensor output at
control system
Measure sensor output
current at control system
Varies with
moisture content
Check cabling back
to junction box
No sensor output at
junction box
Measure sensor output
current at terminals in
junction box
Varies with
moisture content
Check sensor output
configuration
Sensor has shut
down
Disconnect power for 30
seconds and retry or
measure current drawn
from power supply
Normal operation
is 70mA – 150
mA
Check operating
temperature is within
specified range
Internal failure or
incorrect
configuration
Remove sensor, clean
face & check reading (a)
with ceramic face open
and (b) with hand
pressed firmly on
ceramic face. Activate
Average /Hold input if
required
Reading should
change over a
reasonable range
Verify operation with
Hydro-Com
diagnostics