February 7, 2008 Rosslyn, VA: The National Electrical Manufacturers Association (NEMA) has published ANSI C12.11-2007 American National Standard for Instrument Transformers for Revenue Metering 10kV BIL through 350 kV BIL (0.6 kV NSV through 69 kV NSV). This Standard was developed by the Accredited Standards Committee on Electricity Metering, C12, for full consensus approval as an American National Standard. This revised edition supersedes ANSI C12.11-1987 and includes metering accuracy, thermal ratings, and dimensions.

According to Mark Shoemaker, ANSI C12.15 subcommittee member, “This standard covers the general requirements applicable to current transformers and inductively coupled voltage transformers for revenue metering, 10kV through 350kV (0.6 kV NSV through 69 kV NSV).”

The new edition differs from the previous one in both technical and editorial content. Technical changes also include increased focus on current transformer rating factors when ambient temperature is not 30°C, and revisions to rating factor and burden and accuracy performance to fit established industry practice. Editorial revisions include the redrawing of all figures.

 “Annexes (informatives) were added,” Shoemaker said. “Other changes and improvements include informative annexes, suggested utility practices on field application of current transformers, and suggested formats for instrument transformer bar codes.”

This Standard provides recommended minimum requirements for current and voltage transformers used for electricity metering. It is to be used in conjunction with the latest revision of ANSI / IEEE C57.13 and IEEE Std C57.13.6.

The contents and scope of ANSI C12.11-2007 may be viewed, and a hard copy or electronic copy purchased for $184, by visiting NEMA’s Web site, or by contacting IHS at 800-854-7179 (within the U.S.), 303-397-7956 (international), or 303-397-2740 (fax), or on the Web.