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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: 3, Informative) by c0lo on Tuesday March 06 2018, @11:29PM (7 children)
I don't think this is true, given that physiological muscle relaxation time (30-75 ms for half relaxation) is longer than half the period of the AC we are using (10 ms at 50hz).
We** are electrochemical beings, the reaction speed is governed by the mobility of ions in acquatic solutions.
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**Well, almost all of us, @bot may begin to differ.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by edIII on Wednesday March 07 2018, @02:35AM (4 children)
All I can say with authority, is that you cannot let go of DC. I desperately tried. Boy did I try.
Technically, lunchtime is at any moment. It's just a wave function.
(Score: 2) by c0lo on Wednesday March 07 2018, @02:47AM
Sorry, I missed blockquoting what I don't think is true. What my reply comment was addressing is the:
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 5, Informative) by martyb on Wednesday March 07 2018, @03:51AM (2 children)
Wit is intellect, dancing.
(Score: 2) by c0lo on Wednesday March 07 2018, @07:26AM (1 child)
Learnt this in highschool.
It'll still be a painful experience and a potentially (or does 'voltageusly' fits better in the context?) dangerous one.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by martyb on Wednesday March 07 2018, @01:49PM
Agreed. Tapping a live wire with the back of your hand is probably still a bad idea if your hands are wet and you are standing in water.
Wit is intellect, dancing.
(Score: 2, Disagree) by Nuke on Wednesday March 07 2018, @11:20AM (1 child)
c0lo said :
The point is not that you have time to withdraw your hand in 10ms. The point is that DC makes the muscle pull only one way (which may be to grip the wire harder), whereas AC is "neutral" with regard to muscle pulling direction in that the current direction cancels out on average as far as muscle movement is concerned.
I used to work for London Underground railways which has fourth rail electrification at 600v DC. I worked on the track sometimes, and the way the permanent way gangers I was with put it (from some experience) was that the positive DC rail was "sticky". I never experienced it myself.
(Score: 4, Informative) by c0lo on Wednesday March 07 2018, @12:10PM
The fact that the current goes one way or the other is irrelevant for the reaction of the muscle - it will contract anyway, the current mobilizes out the Ca+ ions, causing the proteins in the fibrils to contract. [opentextbc.ca]
If the muscles that are closing your fingers are involved, you won't be able to loosen the grip no mater if it's AC or DC.
To make the matter worse, an electric tetanus can let the muscle contracted for some minutes [allaboutcircuits.com], until the Ca ions repopulate the plasma inside the cells.
The only difference between AC and DC - AC is worse, it causes variable degree of contraction (it "shakes" the muscle) and makes the electrocution painful.
The DC contracts the muscle and keeps it that way in a single go - this is why the "stickiness" description, the muscle is contracted to the max and keeps this way no matter what your mind try to command it to do.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford