29 May
2010
29 May
'10
3:59 a.m.
On 2010-05-28, at 3:26 PM, fons(a)kokkinizita.net wrote:
49 Hz is impossible. It would mean that a clock using
this
frequency would be slow by more than a minute per hour.
Long-term accuracy is extremely high, precisely because clocks
depend on it. And since almost all of Europe is interconnected,
adjusting the frequency must be a _very_ slow process. So errors
of 2 percent really can't be tolerated.
Assume it at your peril. The usual spec is to arrange that over a given 24 hour period,
the total cycle count will result in a mains clock being within 1 second. Often, the power
generators can get much closer and I believe these days they use atomic clocks as the
reference 24 hour time period.
The frequency will drop upon sudden demand. This is often coincident with the start of
adverts in a national sporting event or high ratings soap, end of the news broadcast and
so on. It takes a while to add more power and as a consequence the rotating machines will
slow. Also, things like storm damage removing a significant section from the grid will
result in an increase in frequency.
Vrnc