Crystals, no seriously
You may have heard that Europe is losing time. Unfortunately, why is usually poorly explained — you probably saw three statements (1) a political dispute is causing a minor power shortage, (2) the power shortage causes the grid frequency to drop, and (3) the lower grid frequency causes some clocks to lose time — but not a cohesive explanation on why these are individually true or how they work in concert.
The political situation
Most European countries are tied together in a single synchronous power grid which allows electricity to flow between neighbouring companies.
Two of those countries are Kosovo and Serbia which have a tumultuous past, the up shot of which, is they share a common power grid which Serbia is supposed to support, but Serbia doesn’t recognize Kosovo as a country and therefore they also don’t recognize the power grid links and mutual-obligation between them and has never created policy to control their mutual energy consumption.
Kosovo has had an energy problem for a while, with most of it’s electricity (90%+) produced in a single power plant complex from coal. Recently, they’ve had a net deficit of power (more consumption than production), which — because of their shared infrastructure — causes an unforecast demand on Serbia’s electricity production.
The Cycle Situation
Let’s digress in to how electricity generation works: a magnet passes by induction coils, as the magnet passes a coil an inductive current/voltage is generated, this generates a peaks & valleys signal as the magnets pass. The natural arrangement is to spin the magnets, which generates a very regular signal tied to the RPM of whatever is spinning the generator.
If you’ve ever ridden an exercise bike, you understand what happens as more load is placed on the system, you increase the “resistance” and it get’s harder, unless you work harder, your rate of peddling (speed) decreases. Electric generators work the same way, when more demand is placed on the system, either the speed (frequency) decreases or the prime mover has to work harder to spin the generator at the same speed.
But here’s a secret, induction motors are also induction generators.
This is easy to digest with one generator/motor, if you turn it, power comes out and if you put power in, it turns. But grid-tied generators work as a team, their outputs are all tied together by the transmission grid, this changes the mental model — instead of imaging an exercise bike, imagine a tandem bicycle or one of those bike busses with a dozen people: there’s a little slop in the gearing so when you pedal slightly slower than the average it’s easier and when you pedal slightly faster than the average it’s harder. If you want to keep the same speed going up a hill (more load) everyone either needs to work a little harder or someone needs to work a lot harder, if no-one works harder (or one of the people falls over dead) you’ll slow down.
This (more work) situation is exactly what happened to the European power grid, with an increased draw from Kosovo that Serbia was unable to decouple, it was harder for the connected grid of generators to turn, so they slowed down a little.
About Time
All clocks, well all reliable clocks anyway, need a reliable reference source to count off passing time. For the Babylonian Sundial, that’s the earth orbit relative to the sun and for the classic mechanical clock, it’s a swinging pendulum. At some point, someone realized the power grid has a regular and stable cycle which is universally distributed and already available to any electrically powered clock.
Electric analog clocks use a synchronous motor which turns at the same frequency as the powergrid and then geared down from 3600RPM (60 cylces/second* 60 seconds/minute) to 1RPM by an enormous gear train and then geared down from seconds to minutes to hours by the same gear train most clocks use. Better analog electric clocks have multiple “steps” to the motors revolution and the motor itself rotates as some fraction of the line frequency. Digital clocks just count the number of cycles.
Regardless of the mechanism of the clock, tying the measurement of time to an artifact of power distribution gets a little messy. Back to our bike analogy; imagine your a bicycle courier in a city with strict speed limits; you’re pretty awesome so you can usually pedal fast enough to be right at the speed limit (you’re also magic and never ever stop). You want to keep track of time while you’re on the go, so you stick a card through the spokes and use the flicking card to move the second hand of a clock. This all works, but it means you need to always ride at exactly the speed limit or your clock is wrong — pedal too fast and your clock speeds up, pedal too slow and your clock slows down, this is complicated by your route going uphill and downhill and having heavier packages sometimes or needing to go fast on rainy cobblestones — and this is what happens to the power grid too, regardless of the load it needs to keep the same “speed”.
But you’re smart, you realize you can just ask someone the correct time occasionally and calculate how much faster or slower you need to travel to get your clock back in sync. This (average time calculations) is exactly how real power-grids work, periodically the “grid time” is compared to an accurate time source and the grid speeds up or slows down to correct. In many parts of the world everyone periodically resets their clock twice a year anyway because of daylight saving time, so the drift doesn’t need to be correct forever.
All Clocks?
So does this affect all clocks? No. For starters, it only affects clocks which could get their time-base from the grid so anything without a power-cord is not affected (like watches, portable clocks, or mechanical clocks).
So does this affect all clocks which plug in to the wall? Again, no. Many, if not most, electrically powered clocks have an internal crystal or ceramic resonator (e.g. the archetypical quartz clock); these use the crystal/resonator like a very-very-fast pendulum to generate a stable time-base.
So what is affected? Mostly cheap wall clocks, clock radios, and appliances without any actual computing power (like coffee-makers and microwaves).
Other solutions to power transmission
The problem largely exists because the Synchronous Grid of Continental Europe is, well, synchronous so all parts operate at the same frequency and are directly tied together. The options are for the grid to collectively slow down or completely decouple a region (if that’s even possible, in the case of Kosovo it would involve disconnecting at least Serbia too).
Beyond synchronous connections, other grids tie together using either HVDC Converters to decouple the alternating current into steady DC power and then back in to AC power without directly tying the frequencies together or use Motor-Generators to invert the Generator/Motor relationship; a motor powered by one grid turns a generator connected to another grid. Essentially, instead of using a steam turbine or a diesel engine to turn a generator, the generator is turned by an electrical motor powered by another source. Unfortunately, both of these solutions require either costly infrastructure or are substantially less efficient in operation so synchronously tied grids are the default choice in most situations.
Further Reading
(Aka my open tabs when I wrote this)
Electrical Distribution
Clocks
- Wikipedia page on Electric Clocks — Interesting is the concept of an Electromagnetic clock, these use electricity only to accelerate a pendulum but not as a time-base so these are also unaffected; related but unexplored are early systems which used an electric motor and a slip-clutch to wind the main-spring of a clock.
- Wikipedia on Quartz Clocks
Using the power line frequency to drive a clock
- Renesas AN1342 upscales the 50/60Hz signal to the typical 32.768Hz watch-crystal signal.
- Rod Elliott describes creating a ½Hz signal via TTL counters to drive a typical clock actuator.
