Fluke 5720A service manual Two-Wire Compensation Verification

Calibration and Verification 3

Full Verification

Table 3-4. Low Value Resistance Calibration Using a Current Source

5720A (UUT)

Resistance

1Ω

1.9Ω

10Ω

5700A (UUT)

Resistance

1Ω

1.9Ω

10Ω

Apply Current

100mA

100mA

10mA

Apply Current

100mA

100mA

10mA

5720A Deviation From

Displayed Value (90-day)

±95 ppm

±95 ppm

±25.0 ppm

5700A Deviation From Displayed Value (90-day)

±95 ppm

±95 ppm

±28.0 ppm

5720A Displayed Value

0.9995 to 1.0005

1.89905 to 1.90095

9.997 to 10.003

5700A Displayed Value

0.9995 to 1.0005

1.89905 to 1.90095

9.997 to 10.003

14.For the remaining tests, no current source is required. Verify that each true UUT value is within the limits shown in Table 3-16 for 5700A and Table 3-17 for 5720A.

a.Connect the DMM, set for 4-wire resistance, first to the Resistance Standard equal to the UUT nominal output and then to the UUT itself. In each case, record the resistance standard DMM reading and the resistance standard certified value.

b.Calculate the DMM correction by subtracting the DMM reading from the certified value; enter this calculated value on the test record as DMM ERROR.

c.Move the DMM to the UUT terminals; enter the DMM reading on the test record as DMM UUT RES RDG.

d.Algebraically add the DMM ERROR and the DMM UUT RES RDG; enter the sum on the test record as UUT TRUE RES VALUE.

e.Adjust the output adjustment knob for a UUT Control Display reading equal to the true resistance value previously calculated. The error from the displayed value is also shown on the Control Display. Enter this error (with polarity reversed) on the test record as the UUT DEVIATION FROM DISPLAYED VALUE.

3-17. Two-Wire Compensation Verification

Use the following steps to verify that two-wire compensation operates correctly:

1.Connect the UUT (output set to 100Ω, with external sensing) to the DMM (set for 4- wire resistance measurement). Note the DMM reading.

2.Connect two shorts: DMM SOURCE HI to SENSE HI and DMM SOURCE LO to

SENSE LO.

3.Activate UUT 2-wire compensation.

4.Check that the DMM reading returns to within 4 miliohms of the reading noted in step 1.

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