5 cell voltage, 6 thermocouple voltage, 7 cold junction voltage – Yokogawa Integral Oxygen Analyzer ZR202 User Manual
Page 113: 8 current output, Cell voltage -4, Thermocouple voltage -4, Cold junction voltage -4, Current output -4
<10. Other Functions>
10-4
IM 11M12A01-04E
10.1.5 Cell Voltage
The cell (sensor) voltage will be an index to determine the amount of degradation of the sensor.
The cell voltage corresponds to the oxygen concentration currently being measured. If the indicated
voltage approximates the ideal value (corresponding to the measured oxygen concentration), the
sensor will be assumed to be normal.
The ideal value of the cell voltage (E), when the oxygen concentration measurement temperature is
controlled at 750°C., may be expressed mathematically by:
E = -50.74 log (Px/Pa) [mV]
where, Px: Oxygen concentration in the sample gas
Pa: Oxygen concentration in the reference gas, (21 vol%O
2
)
Table 10.2
shows oxygen concentration versus cell voltage.
Table 10.2
Oxygen Concentration Vs. Cell Voltage, (cell temperature: 750°C)
%O
2
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
mv 117.83
102.56 93.62 87.28 82.36 78.35 74.95 72.01 69.41
%O
2
1
2
3
4
5
6
7
8
9
mv
67.09
51.82
42.88
36.54 31.62 27.61 24.21 21.27 18.67
%O
2
10
21.0
30
40
50
60
70
80
90
mv
16.35
0
-7.86
-14.2
-19.2
-23.1 -26.5 -29.5
-32.1
%O
2
100
mv -34.4
T10.2E.ai
10.1.6 Thermocouple Voltage
The cell temperature is measured with a Type K (chromel-alumel) thermocouple. The thermocouple
cold junction is located in the detector terminal box. The cell temperature and the thermocouple
voltage (including the voltage corresponding to the cold junction temperature) are displayed.
10.1.7 Cold Junction Voltage
This equipment uses temperature-measurement ICs that measure the cold junction temperatures.
The voltage measured by those ICs is displayed.
10.1.8 Current Output
The analog output current is displayed.