Overview - Emerson Rosemount Oxymitter 4000 Instruction Manual

Instruction Manual
IM-106-340, Rev. 4.3
July 2017
Section 8

OVERVIEW

Troubleshooting
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 8-1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 8-3
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 8-3
Alarm Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 8-4
Identifying and Correcting Alarm Indications . . . . . . . . . page 8-5
Heater Not Open, but Unable to Reach 736°C Setpoint . page 8-22
Calibration Passes, but Still Reads Incorrectly . . . . . . . . page 8-22
While the Oxymitter 4000 electronics provides a significant number of
diagnostic alarms to assist in troubleshooting potential problems, it is good to
place these alarms in perspective with respect to the instrument's operating
principles:
When the Zirconium Oxide sensing cell is heated to its setpoint [1357°F
(736°C)], the cell will generate a voltage that rep resents the difference
between the process O
2
O ambient air).
2
Test points, Figure 8-1, are provided to read the raw millivolt value generated
by the thermocouple that controls the cell temperature and also the raw cell
signal.
The cell temperature at test points 3 and 4 should always be stable at
approximately 29 to 30 millivolts, which represents the [1357°F (736°C)]
setpoint temperature.
When flowing calibration gasses, the raw cell millivolt value at test points 1
and 2 should represent the levels on the chart in Figure 8-1. Note that the raw
cell millivolt value increases logarithmically as the O
decreases.
% and the reference O
2
Oxymitter 4000
% inside the probe (20.95%
concentration
2