Instruction Manual
IM-106-350C, Rev 2.2
July 2008
Hazardous Area Oxymitter 5000
http://www.raihome.com
Section 8 Troubleshooting
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page 8-1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 8-3
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 8-3
Alarm Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 8-4
Identifying And Correcting Alarm Indications . . . . . . . . . page 8-5
Heater Not Open, but Unable to Reach 736°C Setpoint . page 8-22
Calibration Passes but Still Reads Incorrectly . . . . . . . . page 8-22
OVERVIEW
While the Hazardous Area Oxymitter 5000 electronics provides a significant
number of diagnostic alarms to assist in troubleshooting potential problems, it
is good to place these alarms in perspective with respect to the instrument's
operating principles:
When the Zirconium Oxide sensing cell is heated to its setpoint [736°C
(1357°F)], the cell will generate a voltage that re presents the difference
between the process O
2
% and the reference O
2
% inside the probe (20.95%
O
2
ambient air).
Test points, Figure 8-1, are provided to read the raw millivolt value generated
by the thermocouple that controls both the cell temperature and the raw cell
signal.
The cell temperature at test points 3 and 4 should always be stable at
approximately 29 to 30 millivolts, which represents the 736°C setpoint
temperature.
When flowing calibration gasses, the raw cell millivolt value at test points 1
and 2 should represent the levels on the chart in Figure 8-1. Note that the raw
cell millivolt value increases logarithmically as the O
2
concentration
decreases.
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