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TESCO Recommendations for New ANSI C12-1 Standards for In-Service Performance Covering Section 5
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Recommendations for new ANSI C12.1 Standards for In-service Performance
Tom Lawton
The Eastern Specialty Company
• Consider new meters
• Consider AMI devices
• Consider new metering device acceptance testing
• Provide definition of Statistical Sampling plans
• Consider performance monitoring of newly certified meters
Subcommittee 25 Objectives Update ANSI C12.1 Section 5:
Current ANSI C12.1 Section 5
Current ANSI C12.1 Section 5 Issues
• Acceptance testing of new meters is not mentioned.
• Statistical sampling plans are not adequately defined.
• Post deployment or performance monitoring of newly certified meters not covered.
Recommended Changes AMI Devices
• New concept of what is a meter…includes everything under the cover.
• AMI communications modules and service disconnect switches.
• Applies sampling and testing requirements to these devices when part of the AMI meter.
Recommended Changes New Meters & Metering Devices
• New meters are covered by sampling and testing requirements.
• As-found, as-left, returned to service tests.
• Accuracy classes in C12.20 (0.2% and 0.5%) referenced.
Recommended Changes Statistical Sampling Plans
• In-service statistical sampling plans should be developed using plans such as: – ANSI/ASQ Z1.9 Sampling Procedures and Tables for
Inspection by Variables – ANSI/ASQ Z1.4 Sampling Procedures and Tables for
Inspection by Attributes
• Provides guidance on how to handle sample failures.
Recommended Changes New Metering Device Acceptance Testing
• Sampling and testing of new meter shipments
• Uses ANSI Z1.4 (attributes) or ANSI Z1.9 (Variables) for sample size and acceptance criteria.
• Specifies an Acceptable Quality Limit (AQL) of 1% or less.
Recommended Changes Performance Monitoring of Newly Certified
Meters
• Evaluate newly certified meters after installation…. Different than in-service.
• Use statistical sampling plan.
Recommended Changes In-Service Requirements for Other Metering
Devices
• Use of statistical sampling plans. • Old Standard included:
– Instrument transformers, demand registers, pulse recorders, coupling-capacitor voltage transformers.
• New Standard includes: – Instrument transformers, demand registers, pulse
recorders, coupling-capacitor voltage transformers, meter communication devices/modules, service switches, non energy measurement features of a meter.
Coordination of ANSI C12.1 & IEC/OIML Requirements
• ANSI working with IEC to coordinate standards (new OIML R46). Many issues!
• Working to tie IEC meter specifications to ANSI requirements. Meters in classes
A - 2%, B – 1%, C – 0.5%, D – 0.2%
• IEC standard does not allow changes to meter after seal is on without testing (similar to Measurement Canada).
Firmware changes???
Coordination of ANSI C12.1 & IEC Requirements
• IEC assumes testing done by government controlled organizations.
• Other differences: – More tests and are run longer – Higher RF frequency range. Accuracy tested during
RF application – Magnetic field strengths higher – Electrical discharge levels higher
Path Forward New Metering Device Acceptance Testing
• Complete sub-committee work and forward proposed draft to full ANSI C12 Main committee at April 5, 2012 meeting (next full committee meeting). Hoping for comments and small revisions then approval and adoption by the October 2012 meeting (Full committee meets twice per year).
• Begin educating EEI members and Utility Commissions that a standard suitable for in-service testing of “smart meters” now exists and can be used as a basis for post-deployment testing programs.
• Appoint members of sub-committee 25 to committee to reconcile differences with IEC and OIML. Members of ANSI committee are already working on both the IEC and the OIML committee but none of the three has an approved new standard yet.
• Edit and keep the new standards consistent and up to date as new equipment and new features reach the marketplace.
