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Instruction Manual
IM-106-910Xi, Original Issue
November 2010
Xi Advanced Electronics
http://www.raihome.com
Section 5 Troubleshooting
Overview of Operating Principles . . . . . . . . . . . . . . . . . . . page 5-1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 5-2
Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 5-2
Electrical Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 5-3
Electrostatic Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . page 5-3
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 5-3
Identifying and Correcting Fault Indications . . . . . . . . . . page 5-3
Calibration Passes, but Still Reads Incorrectly . . . . . . . . page 5-4
Probe Passes Calibration, O
2
Still Reads High . . . . . . . . page 5-5
Probe Passes Calibration, O
2
Still Reads Low . . . . . . . . page 5-6
How do I detect a plugged diffuser? . . . . . . . . . . . . . . . . . page 5-6
Can I calibrate a badly plugged diffuser? . . . . . . . . . . . . page 5-6
OVERVIEW OF
OPERATING
PRINCIPLES
When the Zirconium Oxide sensing cell is heated to its setpoint [736°C
(1357
°F)], the cell will generate a voltage that represents the difference
between the process O
2
% and the reference O
2
% inside the probe (20.95%
O
2
instrument air).
When flowing calibration gases, the raw cell millivolt value should represent
the levels on the chart in Figure 5-1. Note that the raw cell millivolt value
increases logrithmically as the O
2
concentration decreases.