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Power United States Science

The Last DC Power Grid Shut Down in NYC 533

cell-block-9 writes "Today the last section of the old Edison DC power grid will be shut down in Manhattan. 'The last snip of Con Ed's direct current system will take place at 10 East 40th Street, near the Mid-Manhattan Library. That building, like the thousands of other direct current users that have been transitioned over the last several years, now has a converter installed on the premises that can take alternating electricity from the Con Ed power grid and adapt it on premises.' I guess Tesla finally won the argument."
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The Last DC Power Grid Shut Down in NYC

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  • Tesla won but... (Score:5, Insightful)

    by Bryansix ( 761547 ) on Friday November 16, 2007 @07:34PM (#21385265) Homepage
    most people don't even know who Tesla was or that he pushed for the system that we now use to distribute electricity.
    • Re:Tesla won but... (Score:5, Informative)

      by Anonymous Coward on Friday November 16, 2007 @07:35PM (#21385277)
    • by oo7tushar ( 311912 ) <> on Friday November 16, 2007 @07:40PM (#21385315) Homepage
      Just like most of us here on Slashdot don't know (without the assistance of a search engine) who won the 1982 Super Bowl. Different things matter to different people and most people have things to worry about rather than wondering who the proponents of power transport via AC were.

      Most of us here on /. certainly know who Mr. Tesla is and what he pushed for and we should take pleasure in being in such distinct company...except for the trolls and turds.
      • by Paul_Hindt ( 1129979 ) on Friday November 16, 2007 @07:49PM (#21385403) Homepage
        Even trolls need electricity.
      • Scale.. (Score:3, Insightful)

        by msimm ( 580077 )
        Without Tesla there's be nothing to watch the Super Bowl on. I'm pretty sure I could live without the Bengals or the 49ers (some might disagree with me).
    • Re:Tesla won but... (Score:5, Interesting)

      by MikeFM ( 12491 ) on Friday November 16, 2007 @07:41PM (#21385329) Homepage Journal
      Or that he died broke and alone because people like Edison stole his ideas and robbed him blind. Tesla was a genius and could have done so much more for the world if only things weren't controlled by rich people with no vision further than how much money they can make, right away, off an idea. Tesla's failure is a perfect example of capitalism at work.
      • uh (Score:3, Insightful)

        do you have a superior system than capitalism in mind?

        people are fond of pointing out democracy's many failures too

        but the real overriding realization with democracy and capitalism is that however much you think they suck, and they do suck in many ways, they are still better than any other system we can think of and have tried

        so please, criticize capitalism. but unless you can enunciate a superior alternative, your criticism means absolutely nothing
        • Re:uh (Score:5, Insightful)

          by ResidntGeek ( 772730 ) on Friday November 16, 2007 @08:04PM (#21385529) Journal
          No. Capitalism is the best system available, but that doesn't make it fair. It is up to the people within the system to try to make it fair. That includes pointing out the problems with it. His criticism isn't meaningless, it's important.
          • Re:uh (Score:5, Insightful)

            by Pharmboy ( 216950 ) on Friday November 16, 2007 @08:48PM (#21385887) Journal
            Winston Churchill - The inherent vice of capitalism is the unequal sharing of blessings; the inherent virtue of socialism is the equal sharing of miseries.
          • ... the "problem" (which I don't know to be true) is exactly what the GGP said: Edison stole his ideas

            Capitalism isn't the problem; thievery is.

            If you're point had been that Tesla would be the rich, fat cat and that would be bad, then your moral compass would be off but at least your logic would be sound.

        • Re:uh (Score:5, Funny)

          by sweatyboatman ( 457800 ) <sweatyboatman AT hotmail DOT com> on Friday November 16, 2007 @08:05PM (#21385537) Homepage Journal

          do you have a superior system than capitalism in mind?

          I'm sure Tesla wrote it down somewhere.
        • Re: (Score:3, Insightful)

          by Adambomb ( 118938 )
          So shit does not stink in the absence of less fragrant shit.

        • Re: (Score:3, Interesting)

          by vux984 ( 928602 )
          people are fond of pointing out democracy's many failures too

          The failures of democracy aren't democracy itself, but rather of the fact that our implementation of democracy is poor in that it doesn't actually give people the representation in government that they should have. Its too easy to get re-elected, its too hard to break into politics without vast amounts of cash and/or support from existing politicians, its too hard to remove someone who is doing a shitty job, its not nearly transparent enough, the
      • by Tablizer ( 95088 ) on Friday November 16, 2007 @07:50PM (#21385413) Journal
        Or that he died broke and alone because people like Edison stole his ideas ... Tesla's failure is a perfect example of capitalism at work.

        Much of the good ideas that really propel technology are that way. Capitalism rewards manipulative wheeler-dealers far more than creativity. It rewards those who can best exploit creative ideas, not make them.
        • Re: (Score:3, Insightful)

          by reub2000 ( 705806 )
          As in those who can bring creative ideas to a mass market and put it in my hands, not those who can demonstrate a creative idea in their basement.
      • Re: (Score:3, Interesting)

        by Rei ( 128717 )

        That's pretty typical. Example: who do you think of as the inventor of the telephone? Most people would say Alexander Graham Bell. But one could equally credit Antonio Meucci, Johann Philipp Reis, and Elisha Gray. Meucci especially. He beat Bell to it by over 20 years. But he was an Italian immigrant, spoke only poor English, and was effectively broke.

        Example: A couple years ago, I independently came up with this: []
      • Re: (Score:3, Interesting)

        by ScrewMaster ( 602015 )
        Not at all. He died broke because he was as inept financially as he was brilliant scientifically. He tore up a contract that would probably have made him a billionaire because he didn't want to bankrupt Westinghouse. Capitalism has its faults but Tesla's financial state upon his death is not one of them.

        That's not to say that Edison cheating Tesla out of tens of thousands of dollars was a good thing, but Tesla survived that and ultimately ended up working with George Westinghouse. You seem to forget that
    • Very true, and it's a crying shame. Tesla was one of the brightest men of his generation, and the number of inventions and research he left behind is beyond impressive []. That, and he had this crazy-scientist image thing going along aswell :)

      Most people answer with a blank stare whenever in mention the work of Tesla. While Edison's contribution is undeniable, he was more of a salesman than a scientist.
    • Re: (Score:2, Informative)

      While the majority of people don't know who Tesla [] was or what he contributed [] to the modern world, it's safe to say that most of the people here on /. are - at least - aware of him.

      If I ever make it to Belgrade, I'm planning to check out the Nikola Tesla Museum []. :)
    • Re: (Score:3, Funny)

      by markbt73 ( 1032962 )
      I know who Tesla was. "Modern Day Cowboy" was an awesome song.
    • Re: (Score:3, Interesting)

      by Dr. Cody ( 554864 )
      Do to all the anti-gravity devices, free energy machines, and death rays which the Lovecraftian writhing of Tesla's decaying mind gave birth to--and to all the countless nuts propagating them--I would like to paraphrase a widely-attributed quote:

      "When I hear the name 'Tesla,' I reach for my revolver."
    • Re: (Score:3, Funny)

      It's kinda funny that the Tesla Roadster runs off of DC batteries :)
  • Are there any advantages to DC current?
    • Re: (Score:2, Funny)

      by Gregb05 ( 754217 )
      it makes math pretty easy, and your computer is currently running on it.
    • Re: (Score:2, Informative)

      The advantages of AC are mostly in transportation from the power station to the consumer. Internally, electronics use mostly DC, I think (correct me if I'm wrong here). Batteries store and release DC current, a computer's power supply converts to DC, etc.
    • by irn_bru ( 209849 ) on Friday November 16, 2007 @07:42PM (#21385335)
      Depends if you are an elephant or not.
    • Re:Advantages? (Score:5, Informative)

      by oo7tushar ( 311912 ) <> on Friday November 16, 2007 @07:42PM (#21385345) Homepage
      For short distances and for use within IC it's quite useful. The conversion from AC to DC at lower voltages for use within computers produces quite a bit of heat (hence the fan in your PSU, yes I realize that even DC from a higher voltage to DC at a lower voltage produces quite a bit of heat) and so you find that some data centers are moving to converting from AC to DC outside of the cases and transporting DC directly to the servers.

      There was an article on /. about this a while back and perhaps somebody who'd like to be modded up a bit can post the link.
      • Re: (Score:3, Interesting)

        by evanbd ( 210358 )

        Yep, for ever expanding definitions of "short distances." High voltage high power DC silicon is getting better and cheaper, so we're already seeing a few long-haul DC lines where the reduced radiative losses and increased carrying ability of the cables makes it more efficient. On the other end, DC converters are becoming ubiquitous inside electronics. Google wants to standardize on only one voltage (12V) coming from your computer's PSU, and anything that wants another voltage just has its own converter.

    • by Four_One_Nine ( 997288 ) on Friday November 16, 2007 @07:43PM (#21385349) Journal
      Do ATM machines (where we enter our PIN numbers) run on DC current?
    • Re:Advantages? (Score:5, Interesting)

      by Jerry Coffin ( 824726 ) on Friday November 16, 2007 @07:56PM (#21385457)
      A few, but not very many. The main one is that many power uses require DC in the end, so AC has to be rectified and filtered before it's used -- and in doing so, some power is lost. When/where you're using a lot of power in a relatively restricted area, that can make a meaningful difference. Automobiles, for one obvious example, mostly use 12V DC systems (nominally 12V -- really around 14V). Aircraft, for another example, mostly run on 48V DC (IIRC). Some data centers have also gone to having a single big power supply, and then piping DC around to the individual computers. I haven't measured it personally, but they claim this can cut power usage by around 30% in some cases.

      Another difference is that getting shocked by DC tends to be slightly less dangerous than the same shock from AC. A 110V DC shock to bare (unbroken) skin is is quite mild feeling, where most people in the US have found (sometime or other) than 110V AC is fairly uncomfortable, though usually not particularly dangerous (i.e. for every person who dies of electrocution, an unknown but certainly large number of others are shocked with no real consequence beyond surprise and discomfort).
    • Re: (Score:3, Interesting)

      by jumpingfred ( 244629 )
      DC power has many advantages over AC. Lower peak voltages for the same power delivered. No reactive losses. You don't need to synchronize generators feeding the system.

      AC power has one HUGE advantage and maybe other smaller ones. You can cheaply and easily step the voltage up and down. Stepping A DC voltage up and down is much more complex. DC to DC converters are getting cheaper and better to the point that people are proposing and building high voltage DC power distribution systems.
  • by JamesRose ( 1062530 ) on Friday November 16, 2007 @07:39PM (#21385305)
    But Edison electrocuted an elephant, which quite frankly is just an awesome smear campaign.
  • How long until a significant proportion of local users have a hybrid AC/DC system to manage power distribution from power generated on site? Tesla certainly won the medium power, wide area power distribution battle, but there are a lot of developments taking place that will increase the visibility of DC power generation.
  • by Phat_Tony ( 661117 ) on Friday November 16, 2007 @07:44PM (#21385357)
    Frankly, I'm shocked that there was still a DC power system in use in the US.
    • DC still in use (Score:3, Informative)

      DC is actually used extensively in modern power grids, the main advantage being that there is no need to synchronize the phase from different generating stations or subgrids. For example, the Pacific Intertie [] transmits three gigawatts of direct current between Los Angeles and eastern Washington state. (Power is sent from LA to Washington in the winter, covering the demand of electric heating in the pacific northwest; and from Washington to LA in the summer to power our air conditioners.)
    • by Anonymous Coward on Friday November 16, 2007 @08:49PM (#21385899)
      Frankly, I'm shocked that there was still a DC power system in use in the US.

      You're obviously not aware of current events.



      (How apropos: my catchpa is betatron []
  • by themushroom ( 197365 ) on Friday November 16, 2007 @07:44PM (#21385361) Homepage
    Okay, so if the building was running DC, what did the electronics and appliances inside plug into?
  • not with edison, but with death []

    the new yorker hotel is on 34th and 8th. the final dc site near the midtown library is on 40th and 5th

    unfortunately, business acumen and scientific genius do not necessarily go hand in hand

    sad []

    The inventor Nikola Tesla spent the last ten years of his life in near-seclusion in Suite 3327 (where he also died), largely devoting his time to feeding pigeons while occasionally meeting dignitaries.

  • by leighklotz ( 192300 ) on Friday November 16, 2007 @07:47PM (#21385381) Homepage
    When I lived in Cambridge, I sometimes visited friends in Boston who had 600VDC elevators using power from the city.
    Later elevators still used 600VDC but used a dynamotor; that whine you used to hear when you pressed an elevator button elsewhere was the dynamotor starting, to convert to 600VDC from the 120VAC line current. Eventually, elevator manufacturers stopped using it, but when you hear that whine in a medium-old elevator, you know what is is.

    • by Animats ( 122034 ) on Friday November 16, 2007 @08:24PM (#21385707) Homepage

      Later elevators still used 600VDC but used a dynamotor

      What you're hearing is not a dynamotor, but something called a Ward Leonard drive. It's a fixed-speed motor driving a generator, but its purpose is speed control. The field current of the generator, which is small, is adjusted to control the larger output of the generator. The variable output of the generator then drives the elevator motor. The Ward Leonard drive is thus a big power amplifier. Until power semiconductors got big enough, which wasn't really until the 1980s, this was the most effective way to smoothly speed-control large motors.

      A dynamotor has a common field for the input and output sides, but a Ward Leonard drive does not.

      Incidentally, the Wikipedia article in Ward Leonard drives is bogus. Here's a better reference. []

  • by IvyKing ( 732111 ) on Friday November 16, 2007 @07:48PM (#21385389)
    The reason the subways use DC was that at the time the subways were developed, DC motors were smaller, lighter, cheaper and more efficient than variable speed AC motors. AC series motors were developed for railway service (e.g. the New Haven electrification between NYC and New Haven), but those required lower frequency (typically 25 Hz in the US, one exception was the Visalia Electric at 15 Hz and 16 2/3Hz in Europe). Commercial frequency electrification didn't become practical until the 1950's with the development of ignitron and silicon rectifiers.

    AC's advantage of high voltage transmission doesn't apply to subways as 1200V seems to be the limit for third rail. 2400VDC was tried in 1915 on the Michigan Railways (an electric interurban in central Michigan) with abysmal results - the voltage was changed to 1200V within a year of the initial installation.

  • by blind biker ( 1066130 ) on Friday November 16, 2007 @07:51PM (#21385431) Journal
    First of all, let me tell you that Tesla is one of my role models. He is one of the reasons I studied electrical engineering - with a passion. And AC, if you want, is the "winner" for all intents and purposes. The future really validated Tesla's AC system. There have been other folks that helped the adoption of the AC system, like Proteus, another role model for me.

    Said all that however, high-voltage DC, a transport technology that starts to make sense nowadays, thanks to high-power solid-state switching elements, has many advantages over AC in terms of losses and cable utilization. You can transport more energy via DC than AC, across the same thickness cable. And you have practically no losses due to parasitic capacitances and inductances. The corona effect is much easier to control, too.

    So, if I was forced at gunpoint to make a prediction for the electricity transportation in 150 years from now, I'd say hihg-voltage DC.
    • Seems like a DC grid would be a lot easier to have people feed surplus power into from solar cells.
  • Progress. (Score:5, Interesting)

    by LoRdTAW ( 99712 ) on Friday November 16, 2007 @08:09PM (#21385571)
    Kinda sad to me but it was in the way of progress. Lots and lots of buildings still use the old DC elevators here in New York City. Just yesterday I loaded in to Bayard's in downtown Manhattan into a 4x4 foot elevator that I swear Otis himself must have installed. I love how you have to hold the lever to go up and down and manually align the elevator to the floor. The elevator lights are powered by the DC current as well. At Pratt Institute they used to have those old DC elevators that were powered by an ancient motor generator set that was dated back to the 30's. Hell up until 1999 the MTA still had an old DC substation that had Rotary converters for the subway. ConEd also kept the 25 cycle plants running to feed those substations until the early 90's.

    If you want a feel of old DC equipment from the days when if you wanted power you had to make your own, head down to Pratt Institute (located in Brooklyn on Willoughby ave. and Hall st.). They still have 3 steam driven reciprocating piston dynamos built by Ames Iron Works. They work but are only for show. And to top it off they also have a steam turbine dynamo all of which is hooked to a large open marble panel board with knife switches, carbon arc circuit breakers and blade fuses. The panel is still live on the AC side. The Motor generator I mentioned is still there. You can go down to the Pratt engine room and get a tour from Conrad Milster, the Chief engineer who keeps the place running. The large 1930's brick steam boiler still heats the campus and the surrounding neighborhood. The site is an IEEE land mark and walking down there is like going back in time, a real treat.
    • Re: (Score:3, Informative)

      by moosesocks ( 264553 )
      This should give you a pretty good idea of the state of NYC's infrastructure.

      It's been pushed to its absolute limits in terms of age and longevity. The subways have served us well, but it's only been in the last few years that we've stopped neglecting them, and replacing outdated/dangerous systems with more efficient modern counterparts. (There was also the issue that the only people who knew how to service some of the archaic equipment that the MTA was running had been dead for at least 20 years)

      The pum
  • Misinformation (Score:5, Informative)

    by linuxwrangler ( 582055 ) on Friday November 16, 2007 @09:00PM (#21385981)
    It keeps being repeated, even in this article which says "it can be transmitted long distances far more economically than direct current", that AC is more efficient. This is not really true. The advantage (and pretty much the only advantage) that AC has over DC is that it is relatively simple to change voltages.

    Over the short-haul, this is good since losses are primarily resistive and losses are related to the amount of current flowing in the conductors. Power in my neighborhood is delivered at 12,000V and down-converted to 120/240 by transformers located every few houses. Delivering power at 120V would require 100 times the current and massively larger conductors. Once it gets to my house, with the exception of some motors and some lights, everything from TV to stereo to computer ends up having to take that power and reconvert it to DC.

    But AC has far higher losses through capacitance and inductance which become severe over long distances. This is why some current and other planned long-haul transmission routes use DC. A good example of this is the 800-kilovolt DC line that connects into the Sylmar Terminal Station near Los Angeles.

    Apparently, the use of Extra High Voltage DC is being proposed for a number of new long-haul transmission systems and it is the high losses incurred by AC over long distances that is driving the use of DC.
  • by MoFoQ ( 584566 ) on Friday November 16, 2007 @09:22PM (#21386135)
    Especially in the form of High-voltage transmissions. (

    There are some advantages (source: []):

    • Undersea cables, where high capacitance causes additional AC losses. (e.g. 250 km Baltic Cable between Sweden and Germany[9]).
    • Endpoint-to-endpoint long-haul bulk power transmission without intermediate 'taps', for example, in remote areas.
    • Increasing the capacity of an existing power grid in situations where additional wires are difficult or expensive to install.
    • Allowing power transmission between unsynchronised AC distribution systems.
    • Reducing the profile of wiring and pylons for a given power transmission capacity.
    • Connecting remote generating plant to the distribution grid, for example Nelson River Bipole.
    • Stabilizing a predominantly AC power-grid, without increasing maximum prospective short circuit current.
    • Reducing line cost since HVDC transmission requires fewer conductors (i.e. 2 conductors; one is positive another is negative)
    Shoot, it's used in the US and UK (in the "Chunnel").

    Here's a list of notable places that use it: []
  • by WillRobinson ( 159226 ) on Friday November 16, 2007 @09:32PM (#21386197) Journal
    Tesla Man out of Time [] Which is a excellent book on what was going on then.
  • The Backstory (Score:4, Informative)

    by goodie3shoes ( 573521 ) on Friday November 16, 2007 @10:23PM (#21386605)
    This story explains what the original FA obscures; that some old buildings had elevators and pumps designed to run on DC. Sue me if the link doesn't work. []
  • I hope... (Score:4, Funny)

    by Lord Byron II ( 671689 ) on Friday November 16, 2007 @11:25PM (#21386959)
    I hope that the current HD-DVD vs Blu-Ray debate is resolved a bit quicker
  • by sentientbrendan ( 316150 ) on Friday November 16, 2007 @11:53PM (#21387123)
    What sort of electric devices even come with DC input? Most everything has a AC/DC converter built into it. Does that mean that every electronic device on the premises needs both a DC/AC converter and a AC/DC converter chained together? Wow...
  • by bitrex ( 859228 ) on Saturday November 17, 2007 @12:35AM (#21387319)

    I think the most beautiful piece of old AC to DC conversion technology was the mercury arc rectifier...apparently these devices were still used on some branches of the NYC subway until late in the 20th century. A video of one in operation can be seen at []

    A center-tapped transformer was connected to two anodes to form a full-wave rectifier(some had more anodes and were used for 3 phase power), and a pool of liquid mercury was used as the cathode material which would form an arc only if the anode was positive. A keep-alive electrode kept the interior full of vaporized mercury to facilitate the discharge. I'd sure like to have my own. Unfortunately an average sized mercury arc rectifier contains around 2 pounds of liquid mercury, so if it ever broke, my neighborhood would have to be decontaminated, my home razed to the ground, and the rubble buried in a concrete encasement.

There's no such thing as a free lunch. -- Milton Friendman