Keithley 2015, Service Manual

Page: 19 / 158

Performance Verification 1-5
Verification limits
The verification limits stated in this section have been calculated using only the Model 2015
one-year accuracy specifications, and they do not include test equipment uncertainty. If a par-
ticular measurement falls slightly outside the allowable range, recalculate new limits based on
both Model 2015 specifications and pertinent calibration equipment specifications.
Example reading limit calculation
The following is an example of how reading limits have been calculated:
Assume you are testing the 10V DC range using a 10V input value. Using the Model 2015
one-year accuracy specification for 10V DC of ± (30ppm of r 5ppm of range), the cal-
culated limits are:
Reading limits = 10V ± [(10V
×
30ppm) + (10V
×
5ppm)]
Reading limits = 10V ± (.0003 + .00005)
Reading limits = 10V ± .00035V
Reading limits = 9.99965V to 10.00035V
Calculating resistance reading limits
Resistance reading limits must be recalculated based on the actual calibration resistance val-
ues supplied by the equipment manufacturer. Calculations are performed in the same manner as
shown in the preceding example, except, of course, that you should use the actual calibration
resistance values instead of the nominal values when performing your calculations.