Fluke 9100 User Handbook Manual page 171

Provided that the actual output lies between the high and low limits calculated in steps
(4) and (5) above, the 9100 will be within its published accuracy specification. However,
in deciding on test limits applicable to the verification measurement you must also take
into account the accuracy with which the measuring equipment can measure this output.
For example, if the 9100's 2V DC Voltage output was actually 2.0001616V, it would still
be within its accuracy specification. However, a voltmeter with a traceable accuracy of
10ppm at 2V could measure this value as 2.0001816V, leading you to believe that the
9100 was outside its specified accuracy. To obtain true limits for the verification
measurements you must therefore add the total uncertainty of the measuring equipment
to limits obtained in steps (4) and (5) above as follows:
6. Determine the traceable absolute accuracy (including
National Standards uncertainties) of the measuring
equipment at the verification point value.
7. Add the figure determined in step (6) to the high output
limit obtained in step (4) to obtain the high verification
limit.
8. Subtract the figure determined in step (6) from the low
output limit obtained in step (5) to obtain the low
verification limit.
9. Check that the reading obtained on the measuring
equipment, when it is used to measure the 9100 output,
is between the high and low verification limits obtained
in steps (7) and (8) above.
10. To be absolutely certain that the 9100 is within its
specification limits, then the uncertainty of the
measuring equipment must be totally discounted. This
means that in step (7), when we added the measuring
equipment's accuracy derived in step (6), we must now
subtract it [and in step (8), it must be added].
Note: At step (9), we can say that the 9100 achieves its
accuracy specification, but with 2 times the
measuring equipment uncertainty.
At step (10), we have removed the 2-times
uncertainty, so if its reading is within the limits, the
9100 achieves 100% accuracy specification.
Section 9: Verifying the Model 9100 Accuracy Specification
For a voltmeter traceable to
10ppm, absolute accuracy
at 2V is 0.00002V.
2.0001616 + 0.00002
= 2.0001816
1.9998384 - 0.00002
= 1.9998184
If the reading on the
voltmeter is less than
1.9998184V or greater than
2.0001816V then the 9100
is outside its accuracy
specification at 2V.
2.0001616 - 0.00002
= 2.0001416
1.9998384 + 0.00002
= 1.9998584
If the reading on the
voltmeter is greater than
1.9998584V or less than
2.0001416V then the 9100
is within its accuracy
specification at 2V.
9-5
Final Width = 215mm