Measurement Computing WEB-TEMP - Manual (Page 31)

WEB-TEMP User's Guide Specifications
31
Accuracy
Thermocouple measurement accuracy
Table 4. Thermocouple accuracy specifications, including CJC measurement error. All specifications are (±).
Sensor
Type Sensor temperature
(°C) Accuracy error
maximum (°C) Accuracy error typical (°C) Tempco (°C/°C)
J –210 3.098 1.762 0.040
0 1.282 0.724
1200 1.178 0.684
K –210 3.318 1.843 0.045
0 1.292 0.730
1372 1.495 0.799
S –50 1.892 1.058 0.027
250 0.853 0.479
1768 0.734 0.416
R –50 2.010 1.124 0.025
250 0.844 0.475
1768 0.612 0.347
B 250 2.199 2.192 0.004
700 0.824 0.821
1820 0.471 0.469
E –200 3.050 1.708 0.038
0 1.465 0.826
1000 1.010 0.564
T –200 3.226 1.797 0.045
0 1.334 0.754
400 0.856 0.496
N –200 3.406 1.897 0.035
0 1.300 0.735
1300 0.978 0.571
Note 4: Thermocouple measurement accuracy specifications include polynomial linearization, cold-junction
compensation and system noise. These specs are for one year, or 3000 operating hours, whichever
comes first, and for operation of the WEB-TEMP 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 total of four CJC sensors, two per side of the module.
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 5: Thermocouples must be connected to the WEB-TEMP such that they are floating with respect to
AGND. 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 6: When thermocouples are attached to conductive surfaces, the voltage differential between multiple
thermocouples must remain within ±1.4V. For best results, we recommend using insulated or
ungrounded thermocouples when possible.
Semiconductor sensor measurement accuracy
Table 5. Semiconductor sensor accuracy specifications
Sensor Type Temperature Range (°C) Maximum Accuracy Error (°C)
LM35, TMP35 or equivalent –40 to 150 ±0.50