Re: Leap seconds in the European 50.0 Hz power grid

From: Steve Allen <>
Date: Thu, 30 Jan 2003 12:58:25 -0800

On Thu 2003-01-30T12:54:09 +0000, Markus Kuhn hath writ:
> VERDIN phase tracking is perhaps a somewhat pathological case.

True, but I know of someone who built a household clock to use it, and
for someone living in a Navy base town during the early years of the
Reagan era that seemed like a prudent harbinger.

> specification says that the grid phase vectors have to rotate on
> long-term average exactly 50 * 60 * 60 * 24 times per UTC day.

Obviously the grid frequency shift after leap seconds is annoying, and
it is undoubtedly one of the reasons contributing to the notion of
stopping leap seconds. But the question arises as to why the spec
can't easily be changed to indicate that it is per TAI day. My power
company cannot supply me with a reliability of 0.99999997, so I can
never see leap seconds from my household clocks. I don't really
believe that other power companies achieve it either, so what is the
value obtained by a specification like this?

My power reliability is more like 0.999, and various folks in my
region recently experienced outages lasting from hours to weeks. My
recent outage was 8 hours. In order for a household device with
battery backup and internal clock to keep phase with the grid while it
was offline it would have needed an oscillator which would drift only
1 second in 20 days.

Are there any battery-backed devices, let alone household ones, with
internal clocks of this caliber which rely solely on power grid phase
locks to keep SI time?

Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064      Voice: +1 831 459 3046
PGP: 1024/E46978C5   F6 78 D1 10 62 94 8F 2E    49 89 0E FE 26 B4 14 93
Received on Thu Jan 30 2003 - 12:58:40 PST

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