Emerson Rosemount OCX 8800 Reference Manual page 207

Table 8-1: Troubleshooting
O2 Sensor R High (Oxygen sensor resistance high > 5000 Ohms)
O2 Sensor Open (Oxygen sensor disconnected)
Probable cause
Loose or open O cell circuit connection.
2
O cell degraded or failed
2
Ref Current Err (RTD excitation current error) (reference current should be 5.02 mA)
Probable cause
Loose or open lead or circuit wire connection for COe sen-
sor or CJC sensor current loop
COe sensor grounded
COe sensor failed
CJC sensor grounded
CJC sensor failed
O2 Temp Hi (Oxygen sensor heater temperature high, > 750 °C (1382 °F))
Probable cause
High noise in OCX power supply
COe Temp Hi (Combustion sensor heater temperature high, > 310 °C (590 °F))
High noise in OCX power supply
SB Temp Hi (Sample block heater temperature high, > 190 °C (374 °F))
Probable cause
High noise in OCX power supply
Reference Manual
Recommended corrective action
Check O cell circuit wires for breaks or loose connections.
2
Repair lead wire break or loose connections.
Check O cell impedance by reading the O2 Snsr R value via
2
Field Communicator (see Figure
dance is zero, replace O cell with cell replacement kit. If
2
cell impedance is less than 5000 ohms, check for cell hous-
ing ground fault. Repair ground fault. If cell impedance is
greater than 5000 ohms and no ground fault is indicated,
replace O cell with cell replacement kit.
2
Recommended corrective action
Check COe and CJC sensor current loop wiring per
Figure 8-3 and Figure 9-8. Correct wiring faults.
Check resistance of COe sensor leads to ground per
Figure 8-1. Replace COe sensor if resistance is less than 10
M Ohms.
Check resistance of both COe sensors per
place COe sensor if resistance of sensor element is not be-
tween 100 and 250 ohms.
Check resistance of CJC sensor to ground per
Replace CJC sensor if resistance is less than 10 M Ohms.
Check resistance of CJC sensor per
sensor if resistance of sensor is not between 100 and 150
Ohms.
Recommended corrective action
Check power supply for line noise or voltage fluctuations.
Install power line filter kit (PN 6A00171G01) of high quality
line filter for input power.
Check power supply for line noise or voltage fluctuations.
Install power line filter kit (PN 6A00171G01) of high quality
line filter for input power.
Recommended corrective action
Check power supply for line noise or voltage fluctuations.
Install power line filter kit (PN 6A00171G01) of high quality
line filter for input power.
Troubleshooting
6-3, Sheet 1). If cell impe-
Figure 8-1. Re-
Figure 9-7.
Figure 9-7. Replace CJC
197