[time-nuts] Mains Frequency

[Lux, Jim]

On 2/12/21 3:12 AM, Andy Talbot wrote:
> I maintain a real time display of mains frequency, and the cumulative
> timing offset from real time.   It was last reset 10 days ago when we had a
> brief power outage (HV fault a mile or so away).
>
> Since then, for the first few days the timing discrepancy kept within
> plus/minus perhaps 20 seconds.  But in the last couple of days is has crept
> up and is now sitting at +48 seconds.   On average the frequency will have
> been running about 0.013Hz high to give that.
>
> Given Nat. Grid still aim to average out to exactly 50Hz, does anyone know
> if there is a time scale associated with that long-term average?


I would think they try to hold it over 1 day, so that mains driven 
clocks don't run slow or fast.  That being said, I wonder how many 
clocks are still being built using a synchronous motor drive? Given that 
all the clocks on appliances in my kitchen have drifted apart, I'll bet 
they use their internal microcontroller crystal as a reference.