One of the options for electrical device timekeeping has been to count the frequency of the wall electrical power supply. In some cases this count provides a basis for a build-up to other frequency uses.
I know my Nixie Clock projects were mains power frequency counters as originally built and coded.
The North American Electric Reliability Corp. which is the group runs the the electrical grid if proposing a 1 year trial relaxation of the frequency discipline.
The technical reasons seem to be a mix of Cost-Benefit Analysis, troubles keeping Wind Farms on frequency and an assumption that exact frequency just doesn’t matter.
Overseas the use of time by electrical mains frequency counting varies, as many grids have never had the frequency discipline to be reference grade.
Even here much of what does mains frequency count is non-critical – that clock in your kitchen stove, the one in the charger base of your shaver, and basically tend to be the clocks that flash 12:00 after a power outage.
Here is the start of the NERC’s briefing:
Time Error Correction Elimination Field Trial
NERC is investigating the possibility of eliminating Time Error Corrections. NERC, which is currently performing a field trial of the proposed Balancing Authority ACE Limits metric as a part of NERC Project 2007-18, has also been collecting data regarding Interconnection frequency performance, including the number of clock- minutes during which actual frequency dropped below the low Frequency Trigger Limit (FTL) of 59.95 Hertz. During the period of July 2005 through March 2010, approximately 44% of the minutes during which clock-minute actual frequency dropped below the low Frequency Trigger Limit occurred during Time Error Corrections when scheduled frequency was 59.98 Hertz (1,875 of the 4,234 total minutes observed below 59.95 Hertz). Upon further investigation, it was found that almost all of those minutes (1,819 of the 1,875 total) represented frequency deviations that would likely not have dropped frequency below 59.95 Hertz if the scheduled frequency had been 60 Hertz. In other words, it was estimated that approximately 97% were of such a magnitude that if the Time Error Correction had not been in effect, the exceedance of the low FTL would not have occurred.
via TEC Elimination.
I’m not certain how many, if any other than homebrew, amateur radio products are mains frequency counters, and what else may have frequency counter issues.
I know professional equipment we use should be ok, though we’ll check into it.
Also somewhat concerned that the annual less than 20 minutes time error Eastern Grid and less than 8 minutes time error Western Grid (Texas’ separate Grid is expected to stay within 2 minutes a year) may be an annual cumulative calculation and we may experience slow-down/speed-up periods greater than this on the hour-by-hour basis.
Watch the media for more on this, and perhaps it is a good “time” for you too to add a frequency reference source to your shack?