Wisconsin Administrative Code › Public Service Commission › Chapter PSC 113 - Service Rules For Electrical Utilities › Subchapter IX - Electric Meter Testing Programs and Record Requirements › Section PSC 113.0920 - Statistical sample testing plan for new self-contained single phase and 3-wire network meters

Current through June 24, 2024
The new meter sample testing plan described in subs. (1) to
				  (5) may be used for testing new self-contained, single phase and 3-wire network
				  meters without mechanical demand registers or mechanical pulsing devices
				  instead of the new meter test requirements of s.
				  PSC
				  113.0911(1) (a), if the commission
				  authorizes the adoption of the plan by a utility.
(1) Meters, as received from the
				manufacturer, shall be divided into homogeneous lots by manufacturers and type.
				The maximum number of meters in any lot may not exceed 1,000 or be less than
				96. From each such lot assembled, there shall be drawn a coded sample size
				specified in Military Standard 414, (MIL-STD-414) dated 11 June 1957, as shown
				for the various group sizes using Inspection Level IV of Table A-2 on page 4
				and a corresponding actual sample size as shown in Table B-3 on page 45. The
				sample shall be drawn by a random method that ensures that each meter in the
				lot has an equal chance of being selected.
(2) The test criterion for acceptance or
				rejection of each lot shall be based on a separate analysis conducted at both
				the full load and light load test points at unity power factor, as specified in
				s.
				PSC 113.0811(1)
				(c), by means of the Standard Deviation
				Method, Double Specification Limit and with an Acceptable Quality Level (AQL)
				of 0.25 for the full load accuracy analysis and an AQL of 0.40 for the light
				load accuracy analysis as shown in Table B-3, MIL-STD-414, page 45. The
				statistical analysis calculations shall be made following the example outlined
				on page 43 of MIL-STD-414 with the upper and lower specification limits U and L
				designated at 101% and 99% respectively.
(3) One non-registering meter may be removed
				from the sample lot for analysis purposes and replaced with another randomly
				selected meter. If more than one meter in a sample lot is found not to be
				registering, the entire lot shall be rejected.
(4) A lot shall be deemed acceptable for
				installation if the total estimated percent defective (P) is less than the
				appropriate maximum allowable percent defective (M) as determined from Table
				B-3 under the procedures of sub. (2). All meters in an acceptable lot shall be
				deemed to have met the accuracy requirements of s.
				PSC
				113.0811 for placement in service without further
				testing.
(5) A lot shall be
				considered rejected (not acceptable for installation) if the total estimated
				percent defective (P) is greater than or equal to the appropriate maximum
				allowable percent defective (M) as determined from Table B-3 under the
				procedures of sub. (2). All meters in a rejected lot shall be tested and
				adjusted in accordance with the procedures of s.
				PSC
				113.0811 or replaced with meters meeting these
				requirements.