Troubleshooting -1, Overview -1, Figure 8-1. o – Emerson Process Management OXYMITTER 4000 User Manual
Page 97: Sensor mv reading vs. % o, At 736°c (reference air, 20.9% o, Ee section 8, t, Section 8, Hazardous area oxymitter 4000, O sensor performance at 736 c
Instruction Manual
IB-106-340C Rev. 4.1
July 2004
Rosemount Analytical Inc. A Division of Emerson Process Management
Troubleshooting 8-1
Hazardous Area Oxymitter 4000
SECTION 8
TROUBLESHOOTING
8-1 OVERVIEW
While the Hazardous Area Oxymitter 4000
electronics provides a significant number of
diagnostic alarms to assist in troubleshooting
potential problems, it’s good to place these
alarms in perspective with respect to the
instrument’s operating principles:
a. When the Zirconium Oxide sensing cell is
heated to its setpoint [736°C (1357°F)], the
cell will generate a voltage that represents
the difference between the process O
2
%
and the reference O
2
% inside the probe
(20.95% O
2
ambient air).
b. Test points, Figure 8-1, are provided to read
the raw millivolt value generated by the
ther-mocouple that controls both the cell
temperature and the raw cell signal.
c. The cell temperature at test points 3 and 4
should always be stable at approximately
29 to 30 millivolts, which represents the
736°C setpoint temperature.
37260043
100
10
1
0.01
0.1
0
0
50
100
150
200
Concentration O (%)
2
EMF (mV)
O Sensor Performance at 736 C
2
O
O
2
%
100
20
15
10
9
8
7
6
5
4
EMF(mV)
-34
1.0
7.25
16.1
18.4
21.1
23.8
27.2
31.2
36.0
O
2
%
3
2
1
0.8
0.6
0.5
0.4
0.2
0.1
0.01
EMF(mV)
42.3
51.1
66.1
71.0
77.5
81.5
86.3
101.4
116.6
166.8
Figure 8-1. O
2
Sensor mV Reading vs. % O
2
at 736°C (Reference Air, 20.9% O
2
)
8