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Aeroqual Series 930 User Guide
6. Troubleshooting
Fault Description
Possible Cause
Remedy
No Power
Power connection broken
Power supply failure
S930 damaged
Reconnect power cable
Replace 24V power supply
Replace unit
RS485 communications
unstable
RS485/RS232 adaptor faulty
Connections broken
ID incorrect
Noise on cable
Sensor head not fitted correctly
Reconfigure/replace adaptor
Reconnect leads
Check ID
Use shielded twisted pair cable
Insert head correctly
4-20mA output failure
30V input exceeded
Replace S930
Network unstable
ID conflict
Noise on cable
Jumpers set incorrectly
930 units too close together
Modify IDs so that no S930 units share
the same ID
Use shielded twisted pair cable
Set jumpers correctly
The cables between the S930 units
should be a minimum of 30 cm in length
If connected to a display:
Display shows -1
Display shows 1
Display shows -.125
Display oscillated between
min and max
Over-range (>20mA) reverse
loop current
Over-range loop current (>20
mA)
4-20mA loop not powered
Sensor head not fitted correctly
Loop polarity is incorrect. Reverse the
polarity. Incorrect loop polarity can cause
irreversible damage to the 930 unit
Reduce loop current
Power loop. The display requires the
loop to be powered to read correctly
Insert sensor correctly
Sensor failure when new
sensor connected
Insufficient warm-up
Air contaminated
Sensor damaged
Run the sensor for 24-48 hours
Move the sensor to cleaner environment
and check reading
Replace sensor
Sensor showing high
baseline reading under
zero gas conditions
Background gas level higher
than normal
Interference gas present
Sensor zero drift
Sensor damaged
Move sensor to clean environment and
recheck baseline
Move sensor to clean environment and
recheck baseline
Rezero sensor in a clean, stable
environment
Replace sensor
Sensor showing higher
than expected reading in
the presence of sensor
gas
Zero calibration incorrect
Span calibration incorrect
Interference gas present
Sensor calibration lost
Zero calibrate sensor
Span calibrate sensor
Move sensor to clean environment and
check reading upon exposure to know
concentration of gas
Replace sensor