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from the you're-not-just-bored:-the-wall-clock-IS-slow dept.
Electric clocks on continental Europe that are steered by the frequency of the power system are running slow by up to 5 minutes since mid-January according to a news release from the European Network of Transmission System Operators for Electricity ('entsoe'). The transmission system operators (TSOs) will set up a compensation program to correct the time in the future.
Many electric clocks rely on the transmission system frequency to provide a source that minimises long-term drift. Quartz crystals have good short term stability, but dreadful long term stability, so plant and machinery that requires power to be turned on or off at a specific time each day without maintenance over a long period historically used clocks slaved to the power-system frequency, which is kept long-term stable by the system operators to prevent problems in power generation and transmission across national and supra-national grids - for example, attempting to switch supplies to generators that are not synchronised to the grid frequency can severely damage the generator.
It is normal for transmission system operators to allow the frequency to drop slightly at periods of high demand, thus slowing clocks, but usually, the frequency is increased during periods of low demand to ensure the long-term average frequency remains stable.
(Score: 2) by RS3 on Wednesday March 07 2018, @03:05PM
Agreed- the good old days of quality for quality's sake are gone. I just did some more research and found postings from power company workers in most of the world's more developed countries, and 20 years ago they were saying they stopped caring about long-term frequency stability.
Very stable quartz oscillators exist, and you can design devices such that the crystal is located in a fairly thermally stable area of the device. The associated oscillator circuitry can have a lot to do with phase noise, jitter, and long-term stability too.
For very serious stability, crystal ovens https://en.wikipedia.org/wiki/Crystal_oven [wikipedia.org] exist. Not super cheap, but if you need it... https://www.mouser.com/Search/Refine.aspx?Keyword=crystal+oven&Ns=Pricing%7C0&FS=True [mouser.com]
Now I'm feeling inspired to design an inexpensive but stable AC sine wave generator for keeping synchronous motor electric clocks on time. I could envision 1 master station that could even be tied to ntp, and simple slave stations that you'd plug your beautiful analog clocks into.
Reminds me, I had read somewhere that more and more children can't read analog clocks.