Fluke 5720A service manual Direct Current Accuracy Verification Test

5700A/5720A Series II Calibrator

Service Manual

3-20. Direct Current Accuracy Verification Test

Equipment required for the Direct Current Accuracy Verification Test is listed in Table

3-6. Proceed as follows to test accuracy of the dc current function:

Table 3-6. Equipment Required for Direct Current Test

Equipment

DC DMM, 6-1/2 digit High-Current Shunt

Resistance Standards

Model

Wavetek 1281 or HP 3458A Fluke Y5020 (for 5725A only) L&N 4221B (0.1Ω at 2A) Fluke 742A-1 (1Ω at 200 mA) Fluke 742A-10 (10Ω at 20 mA) Fluke 742A-1k (1 kΩ at 2 mA) Fluke 742A-10k (10 kΩ at 200 μA)

Use Table 3-20 (5720A) and Table 3-21 (5700A) for the test records.

1.Connect the dc DMM to the Calibrator output and set the Calibrator for outputs of 200 mV, -200 mV, 2V, and -2V, and record the dc DMM reading at each voltage in Table 3-20 or 3-21.

2.Refer to the resistance standard test report and enter the corrections for all the certified values in ± ppm in column A on the test record.

Note

The STD RES CORRECTION is the difference between the nominal standard resistor value and the certified or true resistor value. For example, if the nominal value is 0.1Ω and the certified value is 0.0999963Ω, the difference equals 0.0000037Ω, or +37 ppm.

3.Connect the equipment as shown in Figure 3-10 using the L&N 0.1Ω resistor.

4.Set the Calibrator for a 2A dc output, and adjust the Calibrator using the output adjustment knob to obtain the characterized voltage reading on the dc DMM. Wait 3 seconds, and record the Calibrator error display reading in ± ppm (Column B).

CALIBRATOR (UUT)

USE INTERNAL GUARD

OUTPUT SENSE

HIHI

LO LO

GND

SHUNT

DC DMM

INPUT

HI

LO

GRD

F3-7.EPS

Figure 3-9. Direct Current Accuracy Test Setup

3-30