In uk.d-i-y raden wrote:
In message , Christopher Tidy
writes
Hi all,

I'm thinking of building an electronic clock control circuit which uses
the 50 Hz mains frequency for time keeping. The reason for this is that
the clock dial is rather large, so probably wouldn't run for long on
battery power, and I don't fancy spending ?40 buying a programmable
quartz oscillator chip.


From my point of view I'd regard an acceptable error as 5 minutes every
6 months. Does anyone know the typical time error seen on the UK grid,
or where I might find this information? Any suggestions would be much
appreciated.

It has to be significantly more accurate than that

Power stations have to be in sync with one another - which requires good
accuracy and stability

Actually not - the power grid will work just fine at 49.7Hz average.
The way that large generators work, at all times other than when you're
starting one up, they are fixed to the grid frequency.
If you try to turn one harder, it just generates more electricity, and
tends to 'push' the whole system higher in frequency.
Of course, one generator can't do this appreciably.

There is no actual need for a national centralised frequency
setting, because of the way it works, as long as some power stations
switch off/on up/down, when the frequency gets above or below 50Hz.
This can be done fine with a 48-52Hz analog meter in the control rooms
of each power station.