Emerson Rosemount OCX 8800 Reference Manual page 209

Table 8-1: Troubleshooting
O2 TC Open (Oxygen sensor heater thermocouple open)
Probable cause
O thermocouple or thermocouple circuit open
2
COe TC Open (Combustibles sensor heater thermocouple open)
Probable cause
Combustibles sensor thermocouple open
SB TC Open (Sample block heater thermocouple open)
Sample block thermocouple or thermocouple circuit open
O2 TC Shorted (Oxygensensor heater thermocouple shorted)
Probable cause
O thermocouple or thermocouple circuit shorted
2
Slow heatup during cold start
COe TC Shorted (Combustibles sensor heater themocouple shorted)
Probable cause
Combustibles sensor thermocouple shorted
Slow heatup during cold start
SB TC shorted (Sample block heater thermocouple shorted)
Probable cause
Sample block thermcouple or thermocouple circuit shor-
ted
Reference Manual
(continued)
Recommended corrective action
Check O thermocouple and circuit wires for breaks or
2
loose connections per Figure
connections or replace failed thermocouple. Perform Reset
procedure from Chapter 3 to continue operation.
Recommended corrective action
Check thermocouple resistance (lead to ground) of refer-
ence and active thermocouples per
thermocouple is open or shorted to ground, replace com-
bustibles sensor.
Check sample block thermocouple and circuit wires for
breaks or loose connections per
loose connections or replace failed thermocouple. Perform
Reset procedure from Chapter 3
Recommended corrective action
Check O thermocouple and circuit wires for short circuit
2
conditions per Figure 8-3. Repair shorted wiring or replace
failed thermocouple. Perform Reset procedure from
Chapter 3 to continue operation.
Perform Reset procedure from
ation. If alarm persists, refer to the O2 Htr Failure alarm
procedure.
Recommended action
Check thermocouple resistance (lead to ground) of refer-
ence and active thermocouples per
thermocouple is open or shorted to ground, replace com-
bustibles sensor.
Perform Reset procedure from
ation. If alarm persists, refer to the COe Htr Failure alarm
procedure.
Recommended action
Check sample block thermocouple and circuit wires for
short circuit condition per Figure
or replace failed thermocouple. Perform Reset procedure
from Chapter 3 to continue operation.
Troubleshooting
8-3. Repair breaks or loose
Figure 8-3. If either
Figure 8-3. Repair breaks or
to continue operation.
Chapter 3 to continue oper-
Figure 8-3. If either
Chapter 3 to continue oper-
8-1. Repair shorted wiring
199