9 ms·

A legacy from the 1800s leaves Tokyo facing blackouts

115 points by abennett 16y ago

robin_reala 16y ago
I’ve often wondered if there are any advantages/disadvantages to the differing electrical frequencies. Any electrical engineers able to enlighten me?
- deleted 16y ago
  [deleted]
- dmm 16y ago
  Low frequencies are convenient for large, slow motors like hoists and trains and will have lower inductive losses. For small, fast motors, a higher frequency may be more convenient. Lights, both incandescent and florescent, will flicker if the frequency is low. Aircraft and spacecraft use 400Hz because the equipment can be lighter and smaller.
- jordanb 16y ago
  I'm not an EE so maybe this is all wrong, but from my understanding, Nikola Tesla determined that the optimum way to transmit power in the early days of AC was 240V@60HZ. 240V was the best tradeoff between safety and voltage drop, and 60HZ was the most efficient frequency for generators and motors. The United States ended up on 120V because of Thomas Edison's lobbying, but took Tesla's recommendation of 60HZ. Europe took Tesla's recommendation of 240V but adjusted the frequency to the "more metric" 50HZ.
  - Luc 16y ago
    The 'more metric' 50Hz made me smile. The Wikipedia article on the history of these frequency choices suggests it was increased from 40Hz to 50Hz to stop visible flickering of lamps. It's an entertaining read: http://en.wikipedia.org/wiki/Utility_frequency#History http://en.wikipedia.org/wiki/Utility_frequency#History
  - masklinn 16y ago
    And Japan went with all of the above at once (they have 120V/50Hz, 120V/60Hz, 240V/50Hz and 240V/60Hz)
    - dicemoose 16y ago
      Japan's actually got 100V/50Hz and 100V/60Hz. http://en.wikipedia.org/wiki/List_of_countries_with_mains_power_plugs,_voltages_and_frequencies http://en.wikipedia.org/wiki/List_of_countries_with_mains_po...
  - brudgers 16y ago
    In the US power transmission is three phase at high voltage (which is where voltage drop is really a big concern). Voltage drop within a building is rarely a concern in the vast majority of buildings. Typical electrical service for small buildings is 240v using two of the three legs. At the service panel each of the legs is available separately as 120v or in combination as 240v. Larger buildings and industrial applications will often use 208v three phase services for power efficiency. Higher 3 phase voltages are also used on a more limited bases
    - DrJokepu 16y ago
      This is also the case in Europe just with different numbers. There are three 230V legs, each within 120 degrees of phase difference from each other. If two are combined, you get 230V * (sin 60) * 2 = 400V which can be used for industrial applications.
      - iuygthyjuk 16y ago
        Not quite - the US has a unique split neutral where an incoming 240V single phase is divided into +/- 120V to drive either 120V to earth or 240V heavy duty appliances. But the dryer supply in the US isn't a multi phase
        mikey_p 16y ago
        That is the single phase that is common in most residential service in the US. It is separate from the 3 phase service you find in light industrial and large office buildings.
    - lutorm 16y ago
      Actually, at least in Sweden, 3-phase 380/400V is available in most homes for power-hungry things like electric stoves, water heaters, etc. I've never seen this in the U.S, so combined with the lower voltage, you need really thick wires to support the 20+A you need to run a 2500W stove. Seems like a waste of copper. I wonder if the U.S. resistive losses are noticeably larger than in Europe. Certainly you notice extension cords for things like vacuum cleaners get very warm in the U.S.
  - iuygthyjuk 16y ago
    There isn't really an optimal - it was mostly a set of accidents to do with already installed turbines and the number of generator poles in a particular design. Lower frequencies were easier to build for early components, 50Hz is about the lowest frequency that you didn't notice flicker on a lamp. Almost all the early non-industrial use of electricity was for lighting - industry tended to generate their own power on-site using whatever equipement they happened to buy. Telsa picked 60hz apparently because it allowed him to reuse clock mechanism in test gear. He also felt that 60sec/60min so 60hz was a 'natural' solution
- bhousel 16y ago
  This page has a lot of interesting info about it: http://en.wikipedia.org/wiki/Utility_frequency http://en.wikipedia.org/wiki/Utility_frequency tl;dr: Nowadays there are no real advantages/disadvantages to prefer 50Hz vs 60Hz. The distinction is mostly just because of historical vendor lock-in.
kevinpet 16y ago
If the grid supports it, they might be able to switch over some generators near the crossover point from 60hz to 50hz. California's San Francisquito hydro plant has been running 50hz turbines from the 1920s at 60hz for decades with no problems. I'm sure you can go the other way as well.
- rchen 16y ago
  They are indeed making preparations to do this, with two of the hydro plants in Nagano (normally producing 60hz) near the crossover point: Ontake and Nezame. Combined they produce about 70,000 KW http://www.nikkei.com/news/category/article/g=96958A9C93819A96E3E1E2E2918DE3E1E2E1E0E2E3E3E2E2E2E2E2E2 http://www.nikkei.com/news/category/article/g=96958A9C93819A...
jdavid 16y ago
In the case of an emergency like this. I would think that most 60hz devices could work on 50hz, and most 50hz devices would work on 60hz. things that would get screwed up are devices that use the signal to time events. some high voltage switches use these things, but overall, i bet washing machines, dish washers, computers, lights, tvs, and radios would just work. even garage door openers should work. clocks and larger equipment might be a bust and maybe some of the robotics stuff at plants might be a bit off, but maybe just maybe it would work. these things are designed to condition the power in most cases within a few percentage points anyways. i bet if it's that dire, they give it a go.
- ars 16y ago
  Not only that, but I bet that in a country with both frequencies companies are not going to want to manufacture and stock both types, so I bet just about everything is designed to be able to handle either frequency.
- patrickyeon 16y ago
  The problem isn't running your commodity devices on the different frequency (most stuff you mentioned transforms and rectifies the wall power, so it's all DC anyway). The problem is getting the grid to work together. West Japan can't send enough power over to East Japan, because the signals don't line up, to leave out the technical bits.
- omh 16y ago
  But what will happen to those that don't work? If they're permanently damaged (and perhaps difficult to replace?) then that might cause more problems than just rolling blackouts.
- iuygthyjuk 16y ago
  It's also slightly tricky (understatement of the year competition) to hook up a 50Hz generator station to a 60Hz grid - if there are still 60Hz generators on that grid. What happens is that the rest of the country tries to back drive your generator + turbine at 20% over it's design speed - this is a bad thing (tm) It's hard enough phasing generators across the country when they are on the same frequency. The normal solution for long haul links, or links between different grids is to use a DC cable. The trouble is that people don't have spare Gigawatt AC:DC DC:AC converters lying around
rchen 16y ago
For those familiar with Japanese geography the 60hz and 50hz grids are broken up like this: http://ja.wikipedia.org/wiki/商用電源周波数#.E6.97.A5.E6.9C.AC.E3.81.AE.E5.95.86.E7.94.A8.E9.9B.BB.E6.BA.90.E5.91.A8.E6.B3.A2.E6.95.B0 http://ja.wikipedia.org/wiki/商用電源周波数#.E6.97.A5.E6.9C.AC.E3.8...
riobard 16y ago
It's amazing that a country known for its industrial standards is stuck with such ancient compatibility issues.
msisk6 16y ago
It might surprise some folks to find the US isn't much different. Although here in the US we're all at 60Hz, we have several regions with different synchronization: http://en.wikipedia.org/wiki/Wide_area_synchronous_grid http://en.wikipedia.org/wiki/Wide_area_synchronous_grid So we also have interconnections with limited capacity between the grids. I recall reading about a new interconnection plant being built between three of our grids on the border of NM and TX with superconducting cables, but can't find the link. Maybe someone else can post it.
- JimmyL 16y ago
  I suspect you're thinking of the Tres Amigas SuperStation (http://www.tresamigasllc.com/ http://www.tresamigasllc.com/), which will connect the Western, Eastern, and Texas Interconnects - and should realistically be online in 2015 or so.

115 points by abennett 16y ago

I’ve often wondered if there are any advantages/disadvantages to the differing electrical frequencies. Any electrical engineers able to enlighten me?

deleted 16y ago
[deleted]
dmm 16y ago
Low frequencies are convenient for large, slow motors like hoists and trains and will have lower inductive losses. For small, fast motors, a higher frequency may be more convenient. Lights, both incandescent and florescent, will flicker if the frequency is low. Aircraft and spacecraft use 400Hz because the equipment can be lighter and smaller.
jordanb 16y ago
I'm not an EE so maybe this is all wrong, but from my understanding, Nikola Tesla determined that the optimum way to transmit power in the early days of AC was 240V@60HZ. 240V was the best tradeoff between safety and voltage drop, and 60HZ was the most efficient frequency for generators and motors. The United States ended up on 120V because of Thomas Edison's lobbying, but took Tesla's recommendation of 60HZ. Europe took Tesla's recommendation of 240V but adjusted the frequency to the "more metric" 50HZ.
- Luc 16y ago
  The 'more metric' 50Hz made me smile. The Wikipedia article on the history of these frequency choices suggests it was increased from 40Hz to 50Hz to stop visible flickering of lamps. It's an entertaining read: http://en.wikipedia.org/wiki/Utility_frequency#History http://en.wikipedia.org/wiki/Utility_frequency#History
- masklinn 16y ago
  And Japan went with all of the above at once (they have 120V/50Hz, 120V/60Hz, 240V/50Hz and 240V/60Hz)
  - dicemoose 16y ago
    Japan's actually got 100V/50Hz and 100V/60Hz. http://en.wikipedia.org/wiki/List_of_countries_with_mains_power_plugs,_voltages_and_frequencies http://en.wikipedia.org/wiki/List_of_countries_with_mains_po...
- brudgers 16y ago
  In the US power transmission is three phase at high voltage (which is where voltage drop is really a big concern). Voltage drop within a building is rarely a concern in the vast majority of buildings. Typical electrical service for small buildings is 240v using two of the three legs. At the service panel each of the legs is available separately as 120v or in combination as 240v. Larger buildings and industrial applications will often use 208v three phase services for power efficiency. Higher 3 phase voltages are also used on a more limited bases
  - DrJokepu 16y ago
    This is also the case in Europe just with different numbers. There are three 230V legs, each within 120 degrees of phase difference from each other. If two are combined, you get 230V * (sin 60) * 2 = 400V which can be used for industrial applications.
    - iuygthyjuk 16y ago
      Not quite - the US has a unique split neutral where an incoming 240V single phase is divided into +/- 120V to drive either 120V to earth or 240V heavy duty appliances. But the dryer supply in the US isn't a multi phase
      - mikey_p 16y ago
        That is the single phase that is common in most residential service in the US. It is separate from the 3 phase service you find in light industrial and large office buildings.
  - lutorm 16y ago
    Actually, at least in Sweden, 3-phase 380/400V is available in most homes for power-hungry things like electric stoves, water heaters, etc. I've never seen this in the U.S, so combined with the lower voltage, you need really thick wires to support the 20+A you need to run a 2500W stove. Seems like a waste of copper. I wonder if the U.S. resistive losses are noticeably larger than in Europe. Certainly you notice extension cords for things like vacuum cleaners get very warm in the U.S.
- iuygthyjuk 16y ago
  There isn't really an optimal - it was mostly a set of accidents to do with already installed turbines and the number of generator poles in a particular design. Lower frequencies were easier to build for early components, 50Hz is about the lowest frequency that you didn't notice flicker on a lamp. Almost all the early non-industrial use of electricity was for lighting - industry tended to generate their own power on-site using whatever equipement they happened to buy. Telsa picked 60hz apparently because it allowed him to reuse clock mechanism in test gear. He also felt that 60sec/60min so 60hz was a 'natural' solution
bhousel 16y ago
This page has a lot of interesting info about it: http://en.wikipedia.org/wiki/Utility_frequency http://en.wikipedia.org/wiki/Utility_frequency tl;dr: Nowadays there are no real advantages/disadvantages to prefer 50Hz vs 60Hz. The distinction is mostly just because of historical vendor lock-in.

kevinpet 16y ago

If the grid supports it, they might be able to switch over some generators near the crossover point from 60hz to 50hz. California's San Francisquito hydro plant has been running 50hz turbines from the 1920s at 60hz for decades with no problems. I'm sure you can go the other way as well.

rchen 16y ago
They are indeed making preparations to do this, with two of the hydro plants in Nagano (normally producing 60hz) near the crossover point: Ontake and Nezame. Combined they produce about 70,000 KW http://www.nikkei.com/news/category/article/g=96958A9C93819A96E3E1E2E2918DE3E1E2E1E0E2E3E3E2E2E2E2E2E2 http://www.nikkei.com/news/category/article/g=96958A9C93819A...

jdavid 16y ago

In the case of an emergency like this. I would think that most 60hz devices could work on 50hz, and most 50hz devices would work on 60hz. things that would get screwed up are devices that use the signal to time events. some high voltage switches use these things, but overall, i bet washing machines, dish washers, computers, lights, tvs, and radios would just work. even garage door openers should work. clocks and larger equipment might be a bust and maybe some of the robotics stuff at plants might be a bit off, but maybe just maybe it would work. these things are designed to condition the power in most cases within a few percentage points anyways. i bet if it's that dire, they give it a go.

ars 16y ago
Not only that, but I bet that in a country with both frequencies companies are not going to want to manufacture and stock both types, so I bet just about everything is designed to be able to handle either frequency.
patrickyeon 16y ago
The problem isn't running your commodity devices on the different frequency (most stuff you mentioned transforms and rectifies the wall power, so it's all DC anyway). The problem is getting the grid to work together. West Japan can't send enough power over to East Japan, because the signals don't line up, to leave out the technical bits.
omh 16y ago
But what will happen to those that don't work? If they're permanently damaged (and perhaps difficult to replace?) then that might cause more problems than just rolling blackouts.
iuygthyjuk 16y ago
It's also slightly tricky (understatement of the year competition) to hook up a 50Hz generator station to a 60Hz grid - if there are still 60Hz generators on that grid. What happens is that the rest of the country tries to back drive your generator + turbine at 20% over it's design speed - this is a bad thing (tm) It's hard enough phasing generators across the country when they are on the same frequency. The normal solution for long haul links, or links between different grids is to use a DC cable. The trouble is that people don't have spare Gigawatt AC:DC DC:AC converters lying around

rchen 16y ago

For those familiar with Japanese geography the 60hz and 50hz grids are broken up like this: http://ja.wikipedia.org/wiki/商用電源周波数#.E6.97.A5.E6.9C.AC.E3.81.AE.E5.95.86.E7.94.A8.E9.9B.BB.E6.BA.90.E5.91.A8.E6.B3.A2.E6.95.B0 http://ja.wikipedia.org/wiki/商用電源周波数#.E6.97.A5.E6.9C.AC.E3.8...

riobard 16y ago

It's amazing that a country known for its industrial standards is stuck with such ancient compatibility issues.

msisk6 16y ago

It might surprise some folks to find the US isn't much different. Although here in the US we're all at 60Hz, we have several regions with different synchronization: http://en.wikipedia.org/wiki/Wide_area_synchronous_grid http://en.wikipedia.org/wiki/Wide_area_synchronous_grid So we also have interconnections with limited capacity between the grids. I recall reading about a new interconnection plant being built between three of our grids on the border of NM and TX with superconducting cables, but can't find the link. Maybe someone else can post it.

JimmyL 16y ago
I suspect you're thinking of the Tres Amigas SuperStation (http://www.tresamigasllc.com/ http://www.tresamigasllc.com/), which will connect the Western, Eastern, and Texas Interconnects - and should realistically be online in 2015 or so.