[time-nuts] Mains Frequency

[David C. Partridge]

IIRC the requirement used to be that it was correct averaged over 24 hours.
I think the Europe wide rules go like this:

 

 

1.	In the short term (seconds to hours), several mechanisms are
employed that continuously try to keep the frequency as close as possible to
50.0000 Hz, but that do not consider the phase (i.e., clock error).
2.	So long as the deviation between the true time and the time
indicated by a mains-driven clock is less than 20 seconds, observed at
08:00, no further measures are taken.
3.	When the deviation exceeds 20 seconds, a correction is scheduled:
during the next day (from midnight to midnight) frequency regulators in the
entire zone will be set to 10 mHz higher or lower than the normal 50.0000
Hz. Ideally, this results in a correction of 17.28 seconds.
4.	The above should normally keep the deviation within about 30
seconds. Only if the deviation exceeds 60 seconds are larger corrections
than 10 mHz allowed.

 

That may however be out of date.

 

David