Appendix C to Subpart C of Part 429 - Sampling Plan for Enforcement Testing of Distribution Transformers
10:3.0.1.4.17.3.13.27.5 : Appendix C
Appendix C to Subpart C of Part 429 - Sampling Plan for Enforcement
Testing of Distribution Transformers
(a) When testing distribution transformers, the number of units
in the sample (m1) shall be in accordance with § 429.47(a) and DOE
shall perform the following number of tests:
(1) If DOE tests four or more units, it will test each unit
once;
(2) If DOE tests two or three units, it will test each unit
twice; or
(3) If DOE tests one unit, it will test that unit four
times.
(b) DOE shall determine compliance as follows:
(1) Compute the mean (X1) of the measured energy performance of
the n1 tests in the first sample as follows:
where Xi
is the measured efficiency of test i.
(2) Compute the sample standard deviation (S1) of the measured
efficiency of the n1 tests in the first sample as follows:
(3) Compute the standard error (SE(X1)) of the mean efficiency
of the first sample as follows:
(4) Compute the sample size discount (SSD(m1)) as follows:
where m1
is the number of units in the sample, and RE is the applicable DOE
efficiency when the test is to determine compliance with the
applicable energy conservation standard, or is the labeled
efficiency when the test is to determine compliance with the
labeled efficiency value.
(5) Compute the lower control limit (LCL1) for the mean of
(6) Compare the mean of the first sample (X1) with the lower
control limit (LCL1) to determine one of the following:
(i) If the mean of the first sample is below the lower control
limit, then the basic model is not compliant and testing is at an
end.
(ii) If the mean is equal to or greater than the lower control
limit, no final determination of compliance or noncompliance can be
made; proceed to Step (7).
(7) Determine the recommended sample size (n) as follows:
Given the value of n, determine one of the following:
(i) If the value of n is less than or equal to n1 and if the
mean energy efficiency of the first sample (X1) is equal to or
greater than the lower control limit (LCL1), the basic model is in
compliance and testing is at an end.
(ii) If the value of n is greater than n1, the basic model is
not compliant. The size of a second sample n2 is determined to be
the smallest integer equal to or greater than the difference n−n1.
If the value of n2 so calculated is greater than 21−n1, set n2
equal to 21−n1.
(8) Compute the combined (X2) mean of the measured energy
performance of the n1 and n2 units of the combined first and second
samples as follows:
(9) Compute the standard error (SE(X2)) of the mean full-load
efficiency of the n1 and n2 units in the combined first and second
samples as follows:
(Note that S1 is the value obtained above in (2).)
(10) Set the lower control limit (LCL2) to,
where t
has the value obtained in (5) and SSD(m1) is sample size discount
determined in (4), and compare the combined sample mean (X2) to the
lower control limit (LCL2) to determine one of the following:
(i) If the mean of the combined sample (X2) is less than the
lower control limit (LCL2), the basic model is not compliant and
testing is at an end.
(ii) If the mean of the combined sample (X2) is equal to or
greater than the lower control limit (LCL2), the basic model is in
compliance and testing is at an end.
[76 FR 12451, Mar. 7, 2011; 76 FR 24781, May 2, 2011]