[LEAPSECS] Time Error Correction "Field Test"

Jonathan E. Hardis jhardis at tcs.wap.org
Sat Jun 18 20:19:59 EDT 2011

A note for you horologists in the U.S....

Beginning in about a month (approx. July 14), the electric power
industry will stop making "Time Error Corrections" on the U.S. power
grid. For those timekeeping devices that rely on 60 Hz power as their
frequency reference, based on past experience those in the Eastern
U.S. will gain time at a rate approximately 20 minutes/year, those in
the Western U.S. will gain time at a rate approximately 8 minutes/
year, and those on the Texas interconnect will gain time at a rate
approximately 2 minutes/year.

While the AC power frequency in the U.S. is nominally 60 Hz, left to
its own devices the grid tends to run fast, at a frequency slightly
greater than 60 Hz. Since the 1930's, when the Telechron clock was
introduced, the electric power industry has made an effort to ensure
that the power frequency was 60 Hz on average by deliberately running
slow to compensate for periods of running fast. Today, the grid is
operated at a target frequency of 59.98 Hz in a procedure called "Time
Error Correction" to maintain the 60 Hz average. However, beginning
next month, the industry plans to stop making Time Error Corrections
in a "field test." The test is planned to last a year and to cover
the entire contiguous U.S.

The electric power industry petitioned the Federal Energy Regulatory
Commission (FERC) for a rules change that would make the industry's
prerogative to end Time Error Correction unambiguous. That petition is
currently in limbo. If the field test is successful -- however
"successful" might be defined -- you can expect the industry to press
their case again at FERC.

For additional information, please see:

1) The filings at FERC. Starting at http://elibrary.ferc.gov/idmws/docket_search.asp
search for all filings on Docket Number RM09-13 ,
2) The information on the field test.

- Jonathan

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