Emerson Process Management 3000 - Manual (Page 110)

Instruction Manual
Appendix A Rev. 3.8
July 2002
A-12 Appendices Rosemount Analytical Inc. A Division of Emerson Process Management
World Class 3000
PROBE TROUBLESHOOTING
A-7 OVERVIEW
The probe troubleshooting section describes
how to identify and isolate faults which may de-
velop in the probe assembly.
Install all protective equipment and
safety ground leads after trouble-
shooting. Failure to replace covers
and ground leads could result in seri-
ous injury or death.
A-8 PROBE TROUBLESHOOTING
a. Probe Faults
Listed below are the four symptoms of
probe failure.
1. The system does not respond to
changes in the oxygen concentration.
2. The system responds to oxygen
changes but does not give the correct
indication.
3. The system does not give an accept-
able indication of the value of the oxy-
gen calibration gas being applied
during calibration.
4. The system takes a long time to return
to the flue gas value after the calibra-
tion gas is turned off.
b. Table A-2 provides a guide to fault finding
for the above symptoms.
c. Figure A-16 and Figure A-17 provide an al-
ternate approach to finding probe related
problems.
Table A-2. Fault Finding
Symptom Check Fault Remedy
1. No response to oxy-
gen concentration
change when:
Thermocouple continuity Thermocouple failure Replace thermocouple
or return probe to
Rosemount.
Heater cold resistance to
be 11 ohm to 14 ohm Heater failure Replace heater or return
probe to Rosemount.
Heater is cold and TC
mV output is less than
set point
Triac O/P to heater Failure of electronics Check HPS and electron-
ics package.
Heater is hot and T/C
mV output is at set
point ±0.2 mV Recorder chart Recorder failure See Recorder Instruction
Manual.
Cell mV input to electron-
ics and cell mV at probe
junction box No cell mV at probe when
calibration gas applied Replace cell or return
probe to Rosemount.
Probe cell mV OK but no
input to electronics Check out cable
connection.
Cell mV satisfactory both
at probe junction box and
input to electronics - fail-
ure of electronics Check electronics
package.