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Time and frequency from electrical power lines



Jonathan E. Hardis, Demetrios Matsakis, Blair Fonville


Due to the efforts of Henry Warren, inventor of the Telechron electric clock, electric power companies have been a source of time and frequency reference for the public for over a hundred years. However, advances in technology and changes in the electric power industry have generated a movement within the industry to end the time-reference service. Power systems in the U.S. operate at a nominal 60 Hz, but in actual operation they accumulate significant phase error. It must be deliberately backed out to keep synchronous clocks on time--a procedure known as Time Error Correction (TEC). Today, many electric clocks still depend on the power system as the reference oscillator--that is, are synchronous--while others use other time references, such as local quartz oscillators and networked time servers--a benefit of the Internet of Things. Little is known about the overall impact of TEC on timekeeping in modern times. The Blackout of 2003 spawned a new regulatory structure for the electric power industry to improve reliability, and as an unanticipated side effect, a decision process that would most likely eliminate TECs was set in motion. The specific proposal is to retire regulatory standards designated BAL-004 and WEQ-006. We review the relevant structure and governing bodies of the U.S. power grids, and report on the current procedural status of these standards. In addition, we review possible scenarios for the future of the power system as an elapsed-time reference absent TEC. For this, we include analysis of the electric power at USNO, as measured over five years. The TECs appear in the data; an analysis with the industry-supplied record of the TECs indicates that without them a time deviation of about 7 1/2 minutes would have occurred on the Eastern Interconnection (grid) between the daylight saving time switches of March 2016 and November 2016.
Proceedings Title
PTTI 2017: Proceedings of the 48th Annual Precise Time and Time Interval Systems and Applications Meeting
January 30 - February 2, 2017, Hyatt Regency Monterey, Monterey, California
Conference Dates
January 30-February 2, 2017
Conference Location
Monterey, CA
Conference Title
48th Annual Precise Time and Time Interval Systems and Applications Meeting


Time Error Correction, Time, Power Line Time
Created March 7, 2017