Fluke 5700A/5720A Series II Calibrator, Service Manual, 13. Current Derating Factors, I Il

5700A/5720A Series II Calibrator

Service Manual

Nominal Value

Table 1-13. Current Derating Factors

Value of Derating Factor K for Over or Under Current

Ω

SHORT 1 1.9 10 19 100 190

1k

1.9 k

10k

19k

100k

190k

1M

1.9 M

10M

19M

100M

Two-Wire Comp

I < IL

[Note 1]

4.4

4.4

4.4

4.4

4.4

4.4

4.4

4.4

4.4

5000

5000

⎯

⎯

⎯

⎯

⎯

⎯

Four-Wire

I < IL

[Note 1]

0.3

300

160

30

16

3.5

2.5

0.4

0.4

50

50

7.5

4.0

1.0

0.53

0.2

0.53

0.1

Four-Wire

IU < I < Imax

[Note 2]

⎯

-5

4 x10

-4

1.5 x 10

-3

1.6 x 10

-3

3 x 10

-2

1 x 10

-2

1.9x 10

3.8

-5

2 x 10

-5

3.8 x 10

-4

1.5 x 10

-4

2.9 x 10

-3

1 x 10

-3

1.9x 10

⎯

Notes:

1.For I < I L, errors occur due to thermally generated voltages within the 5720A. Use the following equation to determine the error, and add this error to the corresponding uncertainty or stability

specification.

Error = K(I L - I)/( I L x I)

Where: Error is in mΩ for all two-wire comp values and four-wire short, and in ppm for the remaining four-wire values.

K is the constant from the above table;

I and IL are expressed in mA for short to 1.9 kΩ;

I and IL are expressed in μA for 10 kΩ to 100 MΩ

2.For IU < I < IMAX errors occur due to self-heating of the resistors in the calibrator. Use the following equation to determine the error in ppm and add this error to the corresponding uncertainty or stability

specification.

2 2

Error in ppm = K(I -IU)

Where: K is the constant from the above table;

I and IU are expressed in mA for short to 19 kΩ;

I and IU are expressed in μA for 100 kΩ to 100 MΩ

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