ETS-Lindgren HI-2790B Calibration Comparison System - Manual (Page 29)

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Calibration Comparison Log 2 dB
Limitation Check
29
6.0 Calibration Comparison Log 2 dB Limitation
Check
See the example logs on pages 31 and 32. Every 30 days review the results of
the 30-day calibration comparison check on all meters, including the
HI-1710 LCR. Note the highest (max) reading and the lowest (min) reading from
all meters for the current 30-day check. This information can be obtained from
the MAX and the MIN columns on the Calibration Comparison Log 30-day Check
log for each meter.
6.1.1 Record the highest max and the lowest min on the Calibration
Comparison Log 2 dB Limitation Check on page 31. For the first
month the highest max will be A and the lowest min will be B.
6.1.2 For the future months A must be updated to the highest max and B
must be updated to the lowest min.
6.1.3 Divide the highest max by the lowest min to obtain the ratio A/B. If
the ratio is less than 1.59, enter Yes in the last column. If the ratio
is greater than 1.59, enter No.
6.1.4 If the ratio is greater than 1.59, action must be taken to reduce the
ratio A/B to less than 1.59. For example, the log on page 32
reports an unacceptable result for March 1985. It indicates a new
meter introduced in January read higher than the other meters, but
that all readings were within acceptable limits. In March, however,
it forced the A/B ratio to exceed 1.59. Removing that meter from
service dropped the A number back to its former level.