Error Analysis - Arbiter Systems Portable Power Sentinel 933A Operation Manual

9.6

Error Analysis

All identified sources of error in the 933A have been quantified using worst-
case manufacturers' performance data. These have then been combined
using a root-sum-of-squares (RSS) method to yield a performance estimate.
Effects due to initial calibration, measurement noise, temperature, and
aging are all included.
the scope of this paper. However, we have found in our many years'
experience building calibration instruments that this method yields the
most realistic estimate of actual worst-case performance, provided that
numerous errors contribute significantly to the overall performance (i.e.,
no one error dominates), and provided that worst-case actual data is used
for the analysis.
The error analysis, used for the 933A power or energy measurements, is
shown in Table 9.1. Similar analyses have been performed for the other
functions of the instrument, and include most of the same factors shown
here.
Temperature Errors, 0-50 C
Current Input, resistor TCR
Voltage Input, resistor ratio
Voltage Reference (x2)
Cal. Source, resistor ratio (x2)
Time Stability, 1 year
Current Input, resistor
Voltage Input, resistor ratio
Voltage Reference (x2)
Cal. Source, resistor ratio (x2)
Measurement Noise
Total RSS Error, Basic
Calibration Errors
Cal. Artifact, Rotek MSB-001A
Traceability to National Standards
Total Error, RSS
Specification (0.05%)
Table 9.1: Power/Energy Error Analysis
The reason for using RSS analysis is beyond
Error, PPM
131
63
50
50
25
25
20
36
40
10
117
50
50
136
500