The Components Of The 5700A/5720A Series Ii Calibrator; Calibrating The 5700A/5720A Series Ii Calibrator - Fluke 5700A Series II Operator's Manual

5700A/5720A Series II
Operators Manual
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Visit www.fluke.com for locations and phone numbers of authorized Fluke service
centers.

1-14. The Components of the 5700A/5720A Series II Calibrator

The calibrator is configured internally as an automated calibration system, with process
controls and consistent procedures. Internal microprocessors control all functions and
monitor performance, using a switching matrix to route signals between modules.
Complete automatic internal diagnostics, both analog and digital, confirm operational
integrity.
Reference amplifiers maintain dc accuracy and stability. Of all technologies available,
reference amplifiers have the lowest noise and best stability. Reference amplifiers in the
calibrator go through special selection processes including long-term aging to ensure high
reliability and performance well within specifications.
The calibrator achieves its exceptional ac voltage accuracy by using a patented Fluke rms
sensor to make real-time AC/DC comparison measurements. The Fluke 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 rms sensor serves as an AC/DC transfer standard to
develop gain and flatness correction constants during calibration. The second Fluke rms
sensor continuously monitors and corrects output voltage during operation.
A patented 26-bit digital-to-analog converter (dac) provides the calibrator with the ability
to 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.

1-15. Calibrating the 5700A/5720A Series II Calibrator

The traditional practice of returning a calibrator to a standards laboratory at regular
intervals for a full calibration is time consuming, expensive, and disruptive to the task to
which the calibrator is being applied. Moreover, it leaves gaps in confidence. You must
rely on manufacturer's specifications to determine if a calibrator will perform acceptably
in an operating environment outside the lab. Also, you must assume that drift is
predictable enough so that performance is within limits between recalls.
The 5700A/5720A Series II Calibrator makes use of Fluke design breakthroughs in the
use of internal check standards and measurement systems. As a result, it can be
completely calibrated in place to full specifications using a small number of convenient,
portable, environmentally tolerant standards available from Fluke. As you will see below,
this procedure is traceable to military standard requirements.
When manufactured, each calibrator is calibrated and thoroughly verified with process
metrology and calibration standards traceable to the U.S. National Bureau of Standards.
A certificate of calibration is included.
A calibration verification procedure described in the 5700A/5720A Series II Service
Manual is recommended every two years or as required by your established policies. This
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Training programs and seminars, including laboratory metrology, system
applications, and product maintenance.
Application help and consulting, including system design, hardware selection,
custom software, site evaluation and installation.
Replacement parts inventory, including recommended spare parts and module kits.