Emerson Rosemount OCX 8800 Reference Manual page 210

Troubleshooting
Table 8-1: Troubleshooting
Slow heatup during cold start
O2 TC Reversed (Oxygen sensor heater thermocouple reversed)
Probable cause
O thermocouple wires reversed
2
COe TC Reversed (Combustibles sensor block heater thermocouple reversed)
Probable cause
Combustibles thermocouple wires reversed
SB TC Reversed (Sample block heater thermocouple reversed)
Probable cause
Sample block thermocouple wires reversed
ADC Failure (Voltage to digital conversion could not complete)
ADC Ref Error (Voltage to digital conversion not accurate)
Probable cause
Incorrect wiring between electronics and sensor housing
Electronics package failure
O2 Htr Failure (Oxygen sensor heater could not reach final temperature)
Probable cause
O heater circuit wiring open
2
O heater open
2
Heater electronics failure
200
(continued)
Perform Reset procedure from
ation. If alarm persists, refer to the SB Htr Failure alarm
procedure.
Recommended action
Check O thermocouple wiring per
2
wiring at the sensor and inside the electronics housing.
Correct reversed wires fault. Perform Reset procedure
from Chapter 3 to continue operation.
Recommended corrective action
Check combustibles thermocouple wiring per
Check the wiring at the sensor and inside the electronics
housing. Correct reversed wires fault. Perform Reset pro-
cedure from Chapter 3 to continue operation.
Recommended action
Check sample block thermocouple wiring per
Check the wiring at the sensor and inside the electronics
housing. Correct reversed wires fault. Perform Reset pro-
cedure from Chapter 3 to continue operation.
Recommended corrective action
Check all wiring between the electronics and sensor hous-
ings per Figure 8-3. Correct wiring faults.
Replace electronics package.
Recommended corrective action
Check O cell heater circuit for broken wire or loose con-
2
nection per Figure 8-3. Repair broken wire or loose connec-
tion.
Check resistance of O heater per
2
heater resistance is 62.5 Ohms. Replace O
is open or has a large resistance.
Check heater fuse F3 in electronics housing per
If open, locate and correct cause of overload. If F3 is not
open, or if cause of overload cannot be found, replace elec-
tronics package.
Chapter 3 to continue oper-
Figure 8-3. Check the
Figure 8-3.
Figure 8-3.
Figure 8-1. Normal O
2
heater if heater
2
Figure 8-1.
OCX 8800