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Xi Advanced Electronics
5-4
Instruction Manual
IM-106-910Xi, Original Issue
November 2010
Table 5-1. Diagnostic/Unit Alarm Fault Definitions
CALIBRATION PASSES,
BUT STILL READS
INCORRECTLY
There are a few fault conditions where no alarm indication is present and the
probe passes calibration, but the O
2
reading may still be incorrect:
An incorrect flow rate of calibration gases can cause a shifted calibration. If
the flow rate of calibration gases is too low, process gases can mix in with the
calibration gases causing a mixture at the cell that is different than what is
noted on the calibration gas bottles. Always set the calibration flow rate when
a new diffuser is installed, and never readjust this flow rate until another new
diffuser is installed. For applications with heavy particulate loading, see
"Probe Passes Calibration, But O
2
Still Appears To Read Low".
No or improper reference air supplied.
Message Status Self Clearing
NV Mem Fail A checksum error was detected in the nonvolatile memory configuration data when the unit was
turned on.
No
Factory Mode On Xi box I/O board, SW4, position 1 is set on "ON". On transmitter electronics board, SW1,
position 1 is set to "ON". This setting should only be used in the factory.
No
Board Temp Hi The transmitter electronic board temperature reading is above 126
°
C or the
Xi unit I/O board temperature reading is above 86
°
C.
No
O2 Htr Ramp Rate The O
2
sensor heater ramp rate is greater than max allowed ramp rate indicating a run away
heater condition.
No
O2 Sensor Open The cell impedance voltage is reading less than -1.1 VDC indicating the O
2
sensor wires may be
disconnected or the O
2
sensor junction may be open.
Yes
O2 TC Open The O
2
cell heater thermocouple voltage is reading more than the hardware configured threshold
voltage. This indicates the thermocouple wires may be disconnected or the thermocouple junction
may be open.
Yes
O2 Temp Low The heater temperature is below the minimum temperature. The predefined low temperature
threshold is the 726
°
C.
Yes
O2 Temp High The heater temperature is above the defined temperature threshold. The high temperature
threshold is the defined by the "High Temp Alm SP
"
parameter. The default value is 750
°
C.
Yes
O2 T/C Shorted The O
2
sensor heater temperature thermocouple voltage is shorted. Yes
O2 T/C Reversed The O
2
sensor heater temperature thermocouple voltage is reading a negative voltage indicating
the thermocouple wire connections may be reversed.
Yes
O2 Htr Failure The O
2
sensor heater temperature is not responding to the controller and can't reach final
temperature set by the device, indicating the O
2
heater may have failed.
Yes
No Flame The Flame Status Relay Input is set to the OFF state indicating it is not safe to operate the O
2
heater and the heater should be turned off.
Yes
Xmtr Disconnect Communication failures detected between transmitter and the I/O board indicating the transmitter
has been disconnected from the I/O board.
Yes
Cal Recommended Probe calibration is recommended. The cell impedance is above 100 ohms and has shifted 50
ohms since the last calibration; the accuracy of the O
2
reading may be compromised.
Yes
Cal Failed A calibration error occurred during the last calibration. The measured slope or constant is outside
the acceptable range. (Slope: 34.5 to 57.5 mv/decade) (Constant: ±20 mv)
Yes
Cell Imp High The O
2
sensor impedance/cell resistance value measurement is greater than 2000 Ohms
indicates the cell may be beyond its useful life.
Yes
CPU Voltage Low The CPU voltage is less than 2.7 V indicating the CPU voltage is too low. Yes
CPU Voltage High The CPU voltage is more than 3.3 V indicating the CPU voltage is too high. Yes
Htr Voltage Low The heater voltage for the O
2
cell heater is below 35 volts. Yes
Htr Voltage High The heater voltage for the O
2
cell heater is above 264 volts. Yes
Low O2 The O
2
reading is below the "Low O2 Alm SP". Yes