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

Bill Hawkins bill at iaxs.net
Sat Oct 7 16:32:00 EDT 2006

Thanks, Roj

The data from the UK grid show the daily cycle of loads
in the 8 day chart. Minimum load is about 4 AM. Back in
the 50's we were told that the time of minimum human 
activity was 4:30 AM, so that's when we could expect an
atomic bomb attack.

Too bad they didn't plot the delta time (integrated
frequency) for 24 hours.

Bill Hawkins

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Roger Glover
Sent: Saturday, October 07, 2006 2:38 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Features of a Precision Clock - Grid

>> 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
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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