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Thermocouple Operation | Up
Instrumentation and Control Volume 1 of 2 | Next
FUNCTIONAL USES OF TEMPERATURE DETECTORS |
Temperature Detectors
THERMOCOUPLES
Other applications provide only the millivolt readout. In order to convert the millivolt reading
to its corresponding temperature, you must refer to tables like the one shown in Figure 7. These
tables can be obtained from the thermocouple manufacturer, and they list the specific temperature
corresponding to a series of millivolt readings.
Figure 7 Temperature-vs-Voltage Reference Table
Temperatures (oC) (IPTS 1968).
Reference Junction 0oC.
oC
0
10
20
30
40
50
60
70
80
90
100
oC
Thermoelectric Voltage in Absolute Millivolts
-
0
0.000
-0.053
-0.103
-0.150
-0.194
-0.236
-
0
+ 0
0.000
0.055
0.113
0.173
0.235
0.299
0.365
0.432
0.502
0.573
0.645
+ 0
100
0.645
0.719
0.795
0.872
0.950
1.029
1.109
1.190
1.273
1.356
1.440
100
200
1.440
1.525
1.611
1.698
1.785
1.873
1.962
2.051
2.141
2.232
2.323
200
300
2.323
2.414
2.506
2.599
2.692
2.786
2.880
2.974
3.069
3.164
3.260
300
400
3.260
3.356
3.452
3.549
3.645
3.743
3.840
3.938
4.036
4.135
4.234
400
500
4.234
4.333
4.432
4.532
4.632
4.732
4.332
4.933
5.034
5.136
5.237
500
600
5.237
5.339
5.442
5.544
5.648
5.751
5.855
5.960
6.064
6.169
6.274
600
700
6.274
6.380
6.486
6.592
6.699
6.805
6.913
7.020
7.128
7.236
7.345
700
800
7.345
7.454
7.563
7.672
7.782
7.892
8.003
8.114
8.225
8.336
8.448
800
900
8.448
8.560
8.673
8.786
8.899
9.012
9.126
9.240
9.355
9.470
9.585
900
1,000
9.585
9.700
9.816
9.932
10.048
10.165
10.282
10.400
10.517
10.635
10.754
1,000
1,100
10.754
10.872
10.991
11.110
11.229
11.348
11.467
11.587
11.707
11.827
11.947
1,100
1,200
11.947
12.067
12.188
12.308
12.429
12.550
12.671
12.792
12.913
13.034
13.155
1,200
1,300
13.155
13.276
13.397
13.519
13.640
13.761
13.883
14.004
14.125
14.247
14.368
1,300
1,400
14.368
14.489
14.610
14.731
14.852
14.973
15.094
15.215
15.336
15.456
15.576
1,400
1,500
15.576
15.697
15.817
15.937
16.057
16.176
16.296
16.415
16.534
16.653
16.771
1,500
1,600
16.771
16.890
17.008
17.125
17.243
17.360
17.477
17.594
17.711
17.826
17.942
1,600
1,700
17.942
18.058
18.170
18.282
18.394
18.504
18.612
1,700
oC
0
10
20
30
40
50
60
70
80
90
100
oC
Summary
Thermocouples are summarized below.
Thermocouple Summary
A thermocouple is constructed of two dissimilar wires joined at one end and
encased in a metal sheath.
The other end of each wire is connected to a meter or measuring circuit.
Heating the measuring junction of the thermocouple produces a voltage that is
greater than the voltage across the reference junction.
The difference between the two voltages is proportional to the difference in
temperature and can be measured on a voltmeter.
Rev. 0
Page 7
IC-01
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