Mich. Admin. Code R. 460.3613

Current through Vol. 24-10, June 15, 2024

Section R. 460.3613 - Solid state meter and metering equipment testing requirements

Rule 613.

(1) The testing of any unit of metering equipment must consist of a comparison of its accuracy with a standard of known accuracy. Units that are not properly connected or that do not meet the accuracy or other requirements of these meter and metering equipment rules at the time of testing must be reconnected or discontinued.

(2) All solid state single-phase, 3-phase, network, self-contained, and transformer-rated meters must comply with both of the following requirements:

(a) Be checked for accuracy as provided for in R 460.3602.

(b) Notwithstanding the provisions of subdivision (a) of this subrule, the testing of solid state meters in service must be governed by a quality control plan that must test meters for accuracy or rejection pursuant to normal inspection as set forth in subrule (3) of this rule, tightened inspection as set forth in subrule (4) of this rule, or reduced inspection as set forth in subrule (5) of this rule, as applicable.

(3) Normal inspection of in-service solid state meters must include all of the following:

(a) Meters must be divided into homogenous groups by manufacturers" types, and certain manufacturers" types must be further subdivided into separate groups by manufacturers" serial numbers.

(b) The meters in each homogeneous group must then be further subdivided into lots of not less than 301, and not more than 35,000, meters each, except that meters of the most recent design may be combined into lots regardless of manufacturers" type, except that where the number of meters of a single type is 8,001 or more, that number of meters must be segregated by types for the formation of lots.

(c) From each assembled lot, a sample of the size specified in table A-2, ANSI/ASQ Z1.9-2003(R2018) using general inspection level II, must be drawn annually. The sample must be drawn at random.

(d) The meters in each sample must be tested for accuracy as follows:

(i) The test criteria for acceptance or rejection of each lot must be based on the test of the sample at heavy load only and must be that designated for double specification limits and an acceptable quality level (AQL) that is not higher than 2.50 (normal inspection) as set forth in table B-3, ANSI/ASQC Z1.9-2003(R2018).

(ii) The necessary calculations must be made pursuant to Example B-3 of ANSI/ASQC Z1.9. The upper and lower specification limits, U and L, must be 102% and 98%, respectively.

(iii) A lot must be rejected if the total estimated percent defective (p) exceeds the appropriate maximum allowable percent defective (M) as determined from table B-3 as specified in paragraph (i) of this subdivision.

(iv) All meters in a rejected lot must be tested within a maximum period of 60 months and comply with the provisions of R 460.3607 or be replaced with meters that comply with the requirements of R 460.3607.

(v) During each calendar year, new meter samples must be drawn as specified in this subrule from all meters in service, with the exception that lots that have been rejected must be excluded from the sampling procedure until all meters included in the rejected lots have been tested.

(e) The electric utility or cooperative shall complete normal inspection before implementing tightened inspection or reduced inspection.

(4) Tightened inspection of in-service meters may be adopted and must include all of the following:

(a) The meters in rejected lots from the previous year must be tested as follows:

(i) From rejected lots, a sample of the lot size specified in table A-2, ANSI/ASQ Z1.9-2003(R2018) using general inspection level III, must be drawn at random.

(ii) The test criteria for acceptance or rejection of each lot must be based on the test at heavy load and must be that designated for double specification limits and an acceptable quality level (AQL) that is not higher than 2.50 (tightened inspection) as set forth in table B-3 of ANSI/ASQ Z1.9-2003(R2018).

(iii) The necessary calculations must be made pursuant to Example B-3 of ANSI/ASQ Z1.9-2003(R2018). The upper and lower specification limits, U and L, must be 102% and 98% respectively.

(b) A lot must be rejected if the total estimated percent defective (p) exceeds the appropriate maximum allowable percent defective (M) as determined from table B-3 specified in paragraph (ii) of subdivision (a).

(c) If the acceptability criteria of the sampling plan are met, then the lot is considered acceptable and must be returned to the variables sampling plan the following year as required by R 460.3613(3). If the acceptability criteria of the sampling plan are not met, then the electric utility or cooperative shall reject that lot and all meters in that lot must be tested and adjusted or replaced within a maximum period of 48 months after the second rejection.

(5) Reduced inspection of in-service meters may be adopted and must include all of the following:

(a) All meters must be divided into homogenous groups by manufacturers" types, and certain manufacturers" types must be further subdivided into separate groups by manufacturers" serial numbers.

(b) The meters in each homogeneous group must then be further subdivided into lots of not less than 301, and not more than 35,000, meters each, except that meters of the most recent design may be combined into lots regardless of manufacturers" type, except that where the number of meters of a single type is 8,001 or more, that number of meters must be segregated by types for the formation of lots.

(c) From each assembled lot, a sample of the lot size specified in table A-2, ANSI/ASQ Z1.9-2003(R2018) using general inspection level I, must be drawn annually. The sample must be drawn at random.

(d) The meters in each sample must be tested for accuracy as follows:

(i) The test criteria for acceptance or rejection of each lot must be based on the test of the sample at heavy load only and must be that designated for double specification limits and an acceptable quality level (AQL) that is not higher than 2.50 (reduced inspection) as set forth in table B-4, ANSI/ASQ Z1.9-2003(R2018).

(ii) The necessary calculations must be made pursuant to Example B-3 of ANSI/ASQ Z1.9-2003(R2018). The upper and lower specification limits, U and L, must be 102% and 98%, respectively.

(iii) A lot must be rejected if the total estimated percent defective (p) exceeds the appropriate maximum allowable percent defective (M) as determined from table B-4 as specified in subrule (5)(d)(i).

(e) When reduced inspection is in effect, the electric utility or cooperative shall return to normal inspection if a lot is rejected and shall adhere to the quality control plan as set forth in subrule (3).

(f) Normal or reduced inspection shall continue unchanged except where the above switching procedures require change.

(g) The electric utility or cooperative may adopt reduced inspection of meters if normal inspection, as set forth in subrule (3) of this rule, has been in effect for the preceding 3 years and all lots of same manufacturer meter type have been accepted on normal inspection in preceding 3 years.

(6) The quality control plan set forth in subrules (3), (4), and (5) of this rule does not alter the rules under which customers may request special tests of meters.

(7) All solid-state meters must comply with all of the following requirements:

(a) Be checked for accuracy in all of the following situations:

(i) When a meter is suspected of being inaccurate or damaged.

(ii) When the accuracy of a meter is questioned by a customer under R 460.3601.

(b) Be inspected for electrical faults when the accuracy of the device is checked.

(c) Have the connections to the customer's circuits checked when the meter is tested on the premises or when removed for testing.

(d) A meter need not be tested or checked for any reason if the device was tested and checked within the previous 12 months except when a complaint is received.

(8) All transformer-rated solid state meters must comply with all of the following requirements:

(a) Be checked for accuracy at unity and 50% power factor on the customer's premises within 60 days after installation, unless the transformers comply with the specifications outlined in the American National Standards Institute standard ANSI C-57.13.

(b) Have the connections to the customer's circuits and multipliers checked when the equipment is tested for accuracy on the premises, when removed for testing, or when instrument transformers are changed.

Mich. Admin. Code R. 460.3613

1983 AACS; 1995 AACS; 2008 AACS; 2019 AACS; 2023 MR 7, Eff. 4/10/2023