5 cell voltage, 6 thermocouple voltage, 7 cold junction voltage – Yokogawa Integral Oxygen Analyzer ZR202 User Manual
Page 122: 8 current output
IM 11M13A01-04E
10-4
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 measured gas
Pa: Oxygen concentration in the reference gas, (21% 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.EPS
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.