Fluke 2625A, 2635A Concluding Calibration, Terminal Connections to Decade Resistance Source

Performance Testing and Calibration	4
Calibration

4-WIRE (4T) CONNECTION

SOURCE

(4-WIRE)

SENSE

(4-WIRE)

11 12 13 14 15 16 17 18 19 20

H L	H L	H L	H L	H L	H L	H L	H L	H L	H L
H L	H L	H L	H L	H L	H L	H L	H L	H L	H L

HYDRA

INPUT

MODULE

1 2 3 4 5 6 7 8 9 10

DECADE

RESISTANCE

SOURCE

s30f.eps

Figure 4-5. 4-Terminal Connections to Decade Resistance Source

3.Remove the module top cover by loosening the two securing screws, fully opening the module top and gently prying either of the hinge ears away from the main body of the module. Refer to Figure 4-1.

4.Connect a KNBS thermocouple to the H (high) and L (low) terminals of channel 15. Refer to Table 4-3 for thermocouple lead colors. Reinstall the module (without the top cover) into the instrument.

5.Press the Hydra POWER button ON.

6.Insert the thermocouple and a mercury thermometer in a stable, thermally-isolated, room-temperature bath. Allow 20 minutes for thermal stabilization.

7.Select the temperature function and K thermocouple type for channel 15. Select the slow measurement rate. Then press MON.

8.Adjust resistor R3 (see Figure 4-1) on the Input Module until Hydra displays the same temperature reading as the mercury thermometer.

9.Calibration of the Input Module is now complete. Remove the Input Module and disconnect the thermocouple. Then attach and secure the module cover.

4-29. Concluding Calibration

At the conclusion of this type of calibration, first make sure the source is cleared. Then press the CAL Enable button on the instrument to exit calibration mode.

Calibration mode can also be exited at any time by sending the *RST Computer Interface command. If this command is sent prior to completion of all calibration points for the selected function, no changes are made to nonvolatile calibration memory for that function.

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