Electronics > Beginners
Is there a particular reason Japan is 100 volts?
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filssavi:
I Know full well of HVDC however it is used only for transmission not distribution,and in particular  the biggest transmission lines are hvdc(basically the ones tying multiple grids together) as the conversion station are extremely expensive, also the voltage is much higher 500 to 800 kV

the distribution grid (Medium voltage and lower) are exclusively AC and they will stay so for the forseable future (transformers there are still the king of the hill)

as for appliances, you would have been right 20 years ago, however now in europe everything (apart from the cheapest chinese crap) is inverter fed, from whasing machines, to expecially AC units, the older on/off type are getting more and more difficult to find.

so to run motors you first take AC rectify it to DC and then syntethyze AC back up. direct 50 Hz machines are already disappearing, especially the single phase ones (that are the worst anyway), this is mostly to get AAA++ efficiency rating, that consumers are quite sensitive on

for the same reasons induction machines will be slowly (again slowly) be replaced in most applications by synchronous machines, BLDC/PMSM for the high end, and synchronous reluctance for the low end
bsfeechannel:

--- Quote from: langwadt on August 30, 2018, 10:29:55 am ---
--- Quote from: GeorgeOfTheJungle on August 30, 2018, 09:13:16 am ---
--- Quote from: Alex Eisenhut on August 30, 2018, 02:46:54 am ---Not as exciting as what they do in Brazil!

--- End quote ---

What do they do in Brazil?

--- End quote ---

https://www.worldstandards.eu/electricity/plug-voltage-by-country/brazil/ ?

--- End quote ---

Well, blame Canada! Literally.  :D

The two standard voltages used in Brazil are the result of the history of its electrification, which started in the 19th century. Back then, as anywhere else in the world, electrification was carried out by many small private companies, each with their own standard voltages and frequencies.

127V roughly reflect the places that were electrified first. And many of them were serviced by the, then Canadian-owned, São Paulo Railway, Light and Power Ltd., popularly known simply as Light, with its 110V standard. Up to this day people  refer to 127V installations by calling them 110 installations.

Other regions were electrified by different companies a little later with 220V (phase-neutral).

Up to the 60s there were two frequencies, 50 and 60Hz. Now the standard is 60Hz.

If Light's standard back then was 110V, why 127V now? Well, there were other "standards": 100, 115, 117 and 120V. 127V is a compromise solution that's easy to obtain from a 220V three-phase Y circuit (220V ≃ 2* 127V * sin(60°) ). So most places where you have 127V (phase-neutral), you can also have  two-phase 220V (phase-neutral-phase) or three-phase 220V with a neutral.

Why don't Brazilians standardize 220V, once and for all? Because they spent all their money converting their units to the metric system.   ;)
boffin:

--- Quote from: janoc on August 30, 2018, 10:23:05 am ---
--- Quote from: tooki on August 30, 2018, 09:50:41 am ---And of course, there were also some system voltages that simply died out over time. Isn’t there still some weird low-frequency AC in some parts of USA for industry or something?

--- End quote ---
You mean like Switzerland's (and also Austria's and Germany's) 15 kV, 16.7 Hz railway overhead wire voltage?

--- End quote ---

Railways are wonderfully unstandardized, The UK for example uses
25kV @ 50Hz (overhead)
750V DC (3rd rail)
1500V DC (3rd rail)
630V DC (3rd/4th rail +420/-210)

Gets even worse when you get to Spain which not only has differing voltages, but even differing rail gauges
Gyro:
Electrolytic corrosion can be another issue for DC distribution. For instance, the London Underground uses the insulated center 4th rail as the return path for DC traction current rather than the running rails (as is done on above ground systems). This was done to prevent electrolytic corrosion of the surrounding pipes and cabling (mostly pipework I suspect).
GeorgeOfTheJungle:

--- Quote from: bsfeechannel on August 30, 2018, 04:40:43 pm ---Why don't Brazilians standardize 220V, once and for all? Because they spent all their money converting their units to the metric system.   ;)

--- End quote ---

... When British Imperial was better, halve something again and again to get exactly 1/2, 1/4, 1/8, 1/16, 1/32 etc. It's soo much easier than dividing by ten! >:D
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