[time-nuts] Features of a Precision Clock - Grid

Roger Glover r.glover at btinternet.com
Sat Oct 7 15:37:54 EDT 2006

>> Does anybody in this group look at power line frequency drift?
> Somebody once told me that they tried to get frequency info from the Palo
> Alto utilities.  When they finally got through to somebody who knew what 
> was
> going on, the answer was "We aren't tariffed for that."
> Does anybody have a URL for the frequency specs?  (US or California.)  I'm
> also interested in the voltage specs.  I poked around on google a while 
> ago
> but didn't find anything interesting.

For the UK grid there's info at :


Which contains real time frequency data for the last 60 minutes. it also 

The normal system frequency is 50Hz. As electricity cannot be stored, the 
instantaneous generation must match the demand being taken from the system. 
If the instantaneous demand is higher than the generation, the system 
frequency will fall. Conversely, if the instantaneous generation is higher 
than the demand, the frequency will rise. System frequency will therefore 
vary around the 50 Hz target and National Grid has statutory obligations to 
maintain the frequency  within +/- 0.5Hz around this level. However, 
National Grid normally operates within more stringent 'operational limits' 
which are set at +/- 0.2Hz.



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