Calibration
Introduction 7
7-3
7-1. Introduction
This chapter explains the Calibration procedures for the Instrument and the Energy
Option.
7-2. Calibration Methods
7-3. Full Calibration Verification and Adjustment
Annual calibration verification and adjustment is recommended to maintain 6100B too
full specifications. If adjustment is required all points in the adjustment point tables
below should be adjusted to nominal.
7-4. Confidence Check
If the Instrument is used mainly at power line frequencies there are a number of
commercially-available measuring power reference standards with accuracies comparable
to that of the 6100B and 6105A. These can be used to perform a confidence check of
6100B accuracy. A single-phase device is sufficient to check both single and poly-phase
6100B systems. Example products are Radian Research RD-22, ZERA COM 1003 or
MTE K2006. Be aware that the results of such measurements have uncertainties far in
excess of those required to check 6100B and 6105A to full specification.
As an example, consider a power measurement made with a RD-22 meter at 120 V, 5 A,
60 Hz with power factor of 0.5. The reported error is 0.006 %.
The RD-22 specification is 0.01 %. Therefore, the uncertainty of the measurement of the
6105A is no better than 0.01 %. The specification of 6105A when calibrated at a Fluke
service center is also 0.01 %; but with a calibration uncertainty of 0.01 % a relaxation of
6105A specification is clearly necessary. A reasonable method is to take the root-sum-of-
squares of the result and the measurement uncertainty (Uncert) to set the new 6105A
specification limit.
In the case of this example:
%012.0006.001.0_
22
=+=specNew
Notice there is no separate measurement of voltage, current or phase angle. This method
relies on the three parameters being independent in the 6105A. It is very unlikely that all
would drift together such that the power value measured was correct.
7-5. Partial Adjustment
The confidence check described above does not provide sufficient information to decide
what parameter should be adjusted if that were deemed necessary. Phase angle is the least
likely parameter to shift unless a fault has occurred. Phase angle is also the hardest to
measure with the accuracy required. The ZERA COM 1003 has the capability to report
voltage and current measurements; so it should be easy to decide what needs to be
adjusted. Follow the process for adjustment described below as required then verify the
adjustment by making a confidence power measurement as described above.
7-6. Confidence Check of a Poly-phase System
A modified version of confidence checking can be used to check a poly-phase system. It
is recommended that all phases are checked before any adjustment is made. Checking a
6135A with a three phase measuring device is clearly the easiest method to follow but
using a single phase device may yield the best results depending on measurement
accuracy. Consider checking a three phase 6135A system with a single phase
measurement device. This method has the advantage that four devices are inter-compared.
There is no reason why different phases in a poly-phase system should drift significantly
22
Re_ sultUncertspecNew +=
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