OM-WEB Series User's Guide
Specifications
33
Accuracy
Thermocouple measurement accuracy
Table 4. Thermocouple accuracy specifications, including CJC measurement error. All specifications are (±).
Sensor
Type
Sensor
temperature
Accuracy error (°C) max
Accuracy error (°C) typ
Tempco (°C/°C)
J
–210 °C
3.098
1.762
0.040
0 °C
1.282
0.724
1200 °C
1.178
0.684
K
–210 °C
3.318
1.843
0.045
0 °C
1.292
0.730
1372 °C
1.495
0.799
S
–50 °C
1.892
1.058
0.027
250 °C
0.853
0.479
1768 °C
0.734
0.416
R
–50 °C
2.010
1.124
0.025
250 °C
0.844
0.475
1768 °C
0.612
0.347
B
250 °C
2.199
2.192
0.004
700 °C
0.824
0.821
1820 °C
0.471
0.469
E
–200 °C
3.050
1.708
0.038
0 °C
1.465
0.826
1000 °C
1.010
0.564
T
–200 °C
3.226
1.797
0.045
0 °C
1.334
0.754
400 °C
0.856
0.496
N
–200 °C
3.406
1.897
0.035
0 °C
1.300
0.735
1300 °C
0.978
0.571
Note 3:
Thermocouple measurement accuracy specifications include polynomial linearization, cold-junction
compensation and system noise. These specifications are for one year, or 3000 operating hours,
whichever comes first, and for operation of the device between 15 °C and 35 °C after 30 minute warm-
up. The tempco should be applied to the accuracy specifications for operation at an ambient
temperature outside of the 15 °C and 35 °C range. There are four CJC sensors — two on each side of
the device. Each CJC sensor is dedicated to one of the four channel pairs. The accuracy listed above
assumes the screw terminals are at the same temperature as the CJC sensor. Errors shown do not
include inherent thermocouple error. Contact your thermocouple supplier for details on the actual
thermocouple accuracy error.
Note 4:
Connect thermocouples to the device such that they are floating with respect to AGND (pins 9, 19, 28,
38, 48). The AGND pins are isolated from earth ground. You can connect thermocouple sensors to
voltages referenced to earth ground as long as the isolation between the AGND pins and earth ground
is maintained.
Note 5:
When thermocouples are attached to conductive surfaces, the voltage differential between multiple
thermocouples must remain within ±1.4V. For best results, use insulated or ungrounded thermocouples
when possible.
