The Calibration Process; Establishing Traceability; Calibration Reports; Calibration Check - Fluke 5700A Series Service Manual

5700A/5720A Series II Calibrator
Service Manual

1-17. The Calibration Process

Calibration requires only three external standards: 10V, 1Ω, and 10 kΩ.
Environmentally-controlled internal check standards provide the primary reference
points. A stored table of calibration constants defines additional reference points for
controlling the output. Traceable calibration and adjustment to the specified level of
performance is accomplished in a semi-automated process that revises this table.
When you finish calibration, but before you save the new constants, the calibrator
presents you with the proposed adjustments as +/- ppm of range and percentage change in
specification for each range and function. You can print a list of changes through the
serial (RS-232C) port, or send them to a computer through either the serial port or the
IEEE-488 port. Also on completion of calibration, the calibrator displays the largest
proposed change.
Calibration can be completed as far as deriving and printing the proposed adjustments
without changing the setting of the rear panel CALIBRATION switch; however, the
switch must be set to ENABLE to store the changes in nonvolatile memory and make
them effective. The switch is recessed to allow the metrologist to cover it with a
calibration sticker to guarantee calibrator integrity.

1-18. Establishing Traceability

Traceability to national standards is established as follows:
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1-19. Calibration Reports

The calibrator stores two sets of calibration constants: the set currently in use and the old
set from the previous calibration. This gives the calibrator the ability at any time to
produce a calibration report of the differences between the present settings and the
settings that were in effect before the last calibration. The report shows changes for each
range and function in +/- ppm of range and in percentage of specification limit. You can
print the report or send it to a host computer through either the RS-232-C or IEEE-488
interface.
If you request a calibration report after doing calibration but before saving the new
constants, the report shows proposed changes to the calibration constants relative to the
previously stored settings.

1-20. Calibration Check

Checking the calibration takes about an hour, and provides you with a means of
documenting the calibrator's performance of a between calibrations. Calibration checking
1-10
Except for the internal ac/dc transfer standard, the internal check standards are
directly calibrated by traceable external standards every time the 5700A/5720A
Series II is calibrated.
The internal ac/dc transfer standard is never adjusted, so its traceability is not
disturbed by calibration. Infrequent verification is done in the traditional way, by
comparing selected ac voltage outputs with an external dc voltage standard through
an external ac/dc transfer standard. Fluke recommends this be done every two years,
or as determined by the policy of your organization.
Infrequent independent verification is also performed on stable parameters, such as
frequency flatness, determined more by circuit geometry and dielectric constants than
time.