Emerson 3000 World Class, Probe Troubleshooting, A-7OVERVIEW, Table A-2.Fault Finding, Symptom

Instruction Manual

Appendix A Rev. 3.6 July 1998

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-2provides a guide to fault finding for the above symptoms.

c.Figure A-14and Figure A-15provide 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:
Heater is cold and TC	Thermocouple continuity	Thermocouple failure	Replace thermocouple
mV output is less than			or return probe to
set point			Rosemount.
	Heater cold resistance to	Heater failure	Replace heater or return
	be 11 ohm to 14 ohm		probe to Rosemount.
	Triac O/P to heater	Failure of electronics	Check HPS and electron-
			ics package.
Heater is hot and T/C	Recorder chart	Recorder failure	See Recorder Instruction
mV output is at set			Manual.
point ±0.2 mV

Cell mV input to electron- ics and cell mV at probe junction box

No cell mV at probe when calibration gas applied

Probe cell mV OK but no input to electronics

Cell mV satisfactory both at probe junction box and input to electronics - fail- ure of electronics

Replace cell or return probe to Rosemount.

Check out cable connection.

Check electronics package.

A-12 Appendices Rosemount Analytical Inc. A Division of Emerson Process Management