Three weeks ago, MET Labs joined other C12 Accredited Standards Committee members in St. Louis, MO at the EEI Transmission, Distribution & Metering Conference to discuss revisions to ANSI C12.1, which provides the basic requirements for all kilowatthour metering devices, both electronic and electromechanical. 

This post highlights changes from the ANSI C12.1-2008 revision to the soon to be released ANSI C12.1-2014, as presented at the meeting by Jim Reed, MET’s Meter Accuracy Lab Manager.  ANSI C12.1 was modified in several sections to keep pace with industry trends and to provide clarity for tests.

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Section 2
A number of definitions were added.

Section 3 (Performance requirements) – Tightened the % errors for portable and reference standards at reference conditions including a specific voltage and current. (Variation for reference condition) – Gave additional percent errors for Portable and Reference Maximum Percent Errors @ 23°C over the designed range of voltage and current.

Section 4
4.7.1 (Test conditions under performance requirements) – Adds some clarity for the calibration level of the meters prior to entering into testing.
4.7.2 (Accuracy tests – internal influences) – A host of changes in this section, including the addition of a 0.5% accuracy classification.   Contact MET for all of the changes in this section. (Insulation) – A few changes, including the addition of a requirement to disconnect components providing a path in parallel with the insulation to be tested. (Effect of high voltage line surges) – Adds an allowance for performing the accuracy performance check once after the completion of both a ring wave test and combination wave test. (Effect of operating temperature) – A few changes, including ramp timing change from 6 to 5 hours. (Effect of relative humidity) – A couple changes, including specifying test current between light load and class amps (same as

Section 5
A number of changes in this section, including:

  • Restructuring to provide clarity, guidelines and generally better reflect updated practices within the industry for in-service and new meter deployment.
  • A test plan must be in place for metering devices at various set intervals (periodic interval plan, variable interval plan or a statistical sampling plan).
  • Provides details for corrective actions that must be taken for any metering device or group of metering devices failing to meet performance criteria.
  • Added recommendations on test data that should be recorded for the annual performance test programs.
  • An Acceptable Quality Limit or AQL of 1.0% or less will be used to develop the acceptance criteria for all metering devices.
  • Service switches to fall under a statistical sampling plan.
  • Performance tests for integrated communication devices.

Appendix D (Periodic testing schedule) – Recommended periodic test program cleaned up to reference AMI meters specifically, and then all other meters.
Appendix F (Variable interval plan) – Includes an example of appropriate test rates based on failed meters.

Questions about the changes?  Ask Pat, our meter approvals expert.

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