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74 Troubleshooting
S
ection 4: Troubleshooting
6
888Xi Advanced Electronics Instruction Manual
December 2012 PN 51-6888Xi
4.5 Calibration passes, but still reads incorrectly
There are a few fault conditions where no alarm indication is present and the probe passes cali-
bration, but the O
2
reading may still be incorrect:
1. 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 mix-
Message Status Alert
Self
Clearing
O2 Temp High
The sensor heater temperature is above the high temperature threshold.
If Extended Temperature feature is not enabled, the predefined high temperature
threshold is 750°C.
If Extended Temperature feature is enabled, the high temperature threshold is
the defined by the “High Temp Alm SP” parameter.
Maint Y
Y
N
O2 T/C Shorted
This diagnostic is only intended to detect a copper short of the thermocouple
connections at the electronics connector. The Cell Heater T/C voltage is reading
close to zero indicating the thermocouple wires may be shorted.
Maint YY
O2 T/C Reversed
The O
2
sensor heater temperature thermocouple voltage is reading a negative
voltage and is decreasing indicating the thermocouple wire connections may be
reversed. Check wiring.
Maint NY
Heater 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.
Maint YY
Burner Flameout
The Flame Status Relay Input is set to the OFF state indicating it is not safe to
operate the sensor heater and the heater should be turned off.
Maint YY
Xmtr Disconnect
Communication failures detected between transmitter and the IO board indicat-
ing the transmitter has been disconnected from the IO board. Check the con-
necting cable.
Maint YY
Cal
Recommended
Probe calibration is recommended. The cell impedance has shifted enough
(above 100 ohms and has shifted 50 ohms) since the last calibration that the
accuracy may be compromised
Maint YN
Cal Failed
A calibration error occurred during the last calibration. Check the Cal Result for
more details. Acknowledge Calibration Failed or recalibrate to clear alarm.
Maint YN
Cell Imp High
The cell impedance reading is above threshold (2000 Ohms) indicating the cell
may be beyond its useful life.
Maint YN
Probe Mismatch
The probe type does not match indicating wrong Transmitter board or probe is
connected.
Maint YY
Xi Disconnect It indicates using Transmitter’s AO when connected to Xi and Xi is disconnected. Maint YY
Cal Changed
Calibration constants have been changed. Acknowledge Calibration to update
constants and clear alarm.
Adv YN
Heater Volt Low
The heater voltage for the O
2
heater is below 30 volt. Check Heater Power.
Adv YN
Probe Changed
The probe or Transmitter board has been changed. Acknowledge Probe Changed
to synchronize calibration constants and clear alarm.
Adv YN
Low O2
The O
2
reading is below the threshold. The threshold is defined by the “Low O2
Alm SP”.
Adv YN
Diffuser Warning
There can be multiple causes for the alert. The diffuser or cal line may be
plugged, the cell may be pressurized, the cal gas bottle may be empty, or cal gas
may not be turned on. Acknowledge Diffuser Warning to clear alarm then check
Diffuser Warn for more details.
Adv YN
Table 4-2 - Diagnostic/Unit Alarm Fault Definitions (2 of 2)
4-20 mA
C
ritical
Alarm