Thermocouple Source - Fluke 74X Series Calibration Manual

74X Series
Calibration Manual

Thermocouple Source

Proceed as follows to verify the Thermocouple Source function. This test uses a Type-K
thermocouple setting on the UUT.
1. Use Type-K thermocouple wire and copper wire to connect the HP3458A to the UUT
2. Set the UUT to the thermocouple source function, linear mode, TC type K; ITS-90
3. Set the HP3458A to measure mV-DC.
4. Wait at least 1 minute for thermal "emfs" (caused by insertion of the connectors) to
5. Source each of the temperatures in Table 14 from the UUT. At each point, correct the
6. Compare the result with the values under the appropriate column in Table 14.
7. When you are finished, press ctwice on the UUT to set the source function to off.
UUT
Output
-180 °C
0 °C
800 °C
1300 °C
24
-TC jack as shown in Figure 11 (the HP3458A is used in place of the 5500A). The
type K-to-copper junctions should be either welded or made with tight screw
terminals and submersed in the lag bath (room temperature). Use the standard
thermometer (0.1% accuracy) to measure the temperature of the lag bath.
scale, internal reference, and °C.
dissipate, and allow the lag bath at least 15 minutes to stabilize.
DMM measured voltage by adding the millivolt equivalent of the Type-K junction at
the lag bath temperature (use the Type-K ITS-90 chart).
This saves battery life.
Table 14. Temperature Source Verification (Type-K Thermocouple, ITS-90)
Nominal Minimum
DC mV 1 Year
-5.5504 -5.5616
0.0000 -0.0197
33.2754 33.2549
52.4103 52.3928
Maximum Minimum
1 Year 2 Year
-5.5390 -5.5653
0.0197 -0.0237
33.2959 33.2508
52.4277 52.3893
Maximum
2 Year
-5.5353
0.0237
33.2999
52.4312