5730A Calibration; The Artifact Calibration Process - Fluke 5730A Getting Started Manual

The Calibrator achieves its exceptional ac voltage accuracy by the use of a patented Fluke
Calibration rms sensor to make real-time ac/dc comparison measurements. The Fluke
Calibration rms sensor is similar in principle to the traditional thermal voltage converter,
but has a shorter time constant, virtually no reversal error, higher signal-to-noise ratio,
and better frequency response. In the Calibrator, one Fluke Calibration rms sensor serves
as an ac/dc or ac/ac transfer standard to develop gain and flatness correction constants
during calibration. The second Fluke Calibration rms sensor continuously monitors and
corrects output voltage during operation.
A patented 26-bit digital-to-analog converter (DAC) lets the Calibrator precisely vary its
output. This is a pulse-width-modulated DAC with linearity typically better than 0.2 ppm
of full scale. As with the other internal functions, the linearity of the DAC is
automatically checked during calibration and analog diagnostics.

5730A Calibration

The 5730A Calibrator makes use of internal check standards and measurement systems.
As a result, it can be completely calibrated in place to full specifications with a small
number of convenient, portable, environmentally-tolerant standards available from Fluke
Calibration. This procedure is traceable to military standard requirements.
When manufactured, each Product is calibrated and thoroughly verified with process
metrology and calibration standards traceable to the International System of units (SI)
through well-recognized national metrology institutes. A certificate of calibration that is
accredited to ISO 17025 is included.
The calibration verification procedure is recommended every 2 years or as required by
established policies. This procedure involves no adjustments. It ensures internal processes
are in control, and establishes parallel external traceability paths for internal functions
such as ac transfers that are never adjusted or corrected.

The Artifact Calibration Process

Calibration requires only three external standards or artifacts: 10 V, 1 Ω, 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 finished with artifact calibration, but before the new constants are saved, the
5730A Calibrator presents the proposed adjustments as +/- ppm of range and percentage
change in specification for each range and function. A list of changes can be sent to the
computer through the serial port, USB device port, Ethernet port, or the IEEE-488 port
using the remote command: CAL_RPT? CHECK. Also on completion of calibration, the
Calibrator shows the largest proposed change.
Calibration can be completed as far as deriving and printing the proposed adjustments
without entering the calibration protection passcode. To save the changes in non-volatile
memory to adjust future outputs from the Calibrator, the passcode must be entered from
the front panel or with a remote command. The passcode entry menu is shown on the
display when necessary.
Multifunction Calibrator
5730A Calibration
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