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It's Time To Replace 60 Hz 110V Electricity

Discussion in 'General Electronics' started by Mark Thorson, Aug 16, 2003.

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  1. Mark Thorson

    Mark Thorson Guest

    Now that the blackout has shaken the public's faith in
    the electric power industry, we have an opportunity
    to make much-needed large-scale changes in how
    electricity is distributed.

    The system we use now evolved from 19th-century
    technology, with patches to adapt it to the rapid
    growth which occurred in the 20th century. If we
    were creating a new system today, we would never
    choose 60 Hz AC. That's almost an ideal frequency
    for causing heart fibrillation during an electric shock.
    Much better would be the Air Force standard, which
    is 115 VAC at 400 Hz. The main reason they chose
    400 Hz is not safety, however, but to make transformers
    smaller and more efficient. Weight is a major issue
    for aircraft.

    The Army uses 28 VDC. This is also safer, both because
    of the lower voltage and absence of fibrillation hazard.
    Edison originally promoted DC electricity in the late
    19th century, but it lost out to the AC system because
    the transformer technology of the time required AC.
    Had the DC system been adopted, the electrical generating
    plants would have to be located close to the consumers
    of electricity.

    We don't have that limitation. With solid-state electronic
    switching power converters, we could use high-voltage DC
    for distributing power. There would some losses in the switches,
    but these are more than compensated by reduced losses in the
    transmission lines.

    Solar-power enthusiasts often convert their homes to 12 VDC.
    That's for compatibility with cheap multicell lead-acid batteries
    used to store power.

    I propose that now is the time to adopt a new standard.
    A DC standard would be best, to reduce the shock hazard.
    The voltage should be the lowest practical voltage, both for
    the improved safety and perhaps equally important for the
    perception of improved safety in the mind of the public.
    If you go much below 12V, the wires needed for high-power
    appliances become rather thick. If you go much above
    28 VDC, the shock hazard from touching exposed live wires
    or terminals becomes too high.
  2. Sam Wormley

    Sam Wormley Guest

    Reduce the grid load--put these in new homes.
  3. Old Man

    Old Man Guest

    DOA. Skin effect. [Old Man]
  4. Bill Vajk

    Bill Vajk Guest

    If you knew anything about this subject you would realize
    how absurd your proposal is. Start with loss tables and
    wire sizing in the National electrical code. Annotated
    versions are sold, including an annotated version put out
    by the National Fire Protection Association.

    Shock hazzard is well managed these days by ground fault
    interrupters. They're reliable and inexpensive, under $10
    per unit, much less in quantity. They present a better
    life safety solution than changing the present distribution
    system. Such devices are already required for all garage
    and outdoor outlets as well as in kitchens and bathrooms
    within reach of water. Nothing is keeping anyone from using
    this form of protection feature everywhere in their home.
  5. Uncle Al

    Uncle Al Guest

    A Liberal!
    First, interminable studies. Second, political power brokerage and
    favors. Third... social activism! We don't need no stinking
    Parroting the Media. Kirchhoff's laws haven't changed, neither have
    impedence and phase matching. A wire is a wire. What changes would
    you make in substation infrastructure and software control modalties?
    400Hz power lines would be lovely EM radiation sources. Long haul
    lines would have major inductance losses.
    Absolutely forget DC.
    Who pays for it, you?
    You know nothing about large scale distribution. Edison had his ass
    cooked clear off by Steinmetz' AC. To substitute proven robust
    existing infrastructure with delicate new hardware is a very NASA-like
    act. One presumes the bottom line will be similar - financial and
    Screw public perception. One doesn't allow idiots to vote on
    important things - or listen to them if they do.
    You are eloquent about that which you know nothing.
  6. Old Man points out skin effect as a big problem. It is. In addition to
    that, consumers have many appliances which have induction motors and
    transformers. A 60Hz transformer is inefficient at 400Hz and may
    overheat becoming a fire hazzard. Induction motors designed for 60Hz
    will likely not run at all on 400Hz and if by some miracle such a motor
    runs, it will run at the wrong speed. Thus there is a large direct cost
    in replacing all of the wires in the HV distribution system and in
    consumer replacing non-functional appliances.
    Historically, early AC systems were 25Hz, 50Hz and 60Hz. 25Hz is to low
    because 25Hz motors and transformers are quite large. 50Hz was preferred
    in some parts of the world while 60Hz was preferred in the US.

    Anecdotally, when I was in the Army, the power I used for the equipment
    I was responsible for was 240 volt 3 phase AC. Even a piece of
    transportable equipment I worked on was brought to my location for
    repair along with a 100KW diesel generator set that gave me the required
    240 volt 3 phase AC. On 28volts DC, this equipment would have required
    3,570 amperes. 28 volts DC was not an option for that equipment.
    Megavolt power transmission is commonly DC.
    Let's look at the impact on appliances. A 1500 watt microwave oven will
    probably draw 80 to 90 amperes at 28 volts. The power cord will have a
    minimum of 2 4AWG conductors. 90 amp wall outlets should be interesting.
    Now a modest home typically has about a 100 amp service at 240 volts
    single phase. An equivalent service at 28 volts DC is 785 amperes. That
    probably gets you up to about 00 or 000AWG wire for hom distribution.
    That's really expensive.

    I don't think we are ready to replace the power grid completely, replace
    all household appliances and have to live with power cords the size of
    elephant trunks (one place I worked had 480 volt 3 phase wall outlets
    and the cords we plugged into them we called elephant trunks since it
    took two men to plug in an appliance such as a 50KW power supply).

  7. Steve Spence

    Steve Spence Guest

    wonderful. drive up the price of natural gas and use up what little supply
    we have. never mind that these things are not available yet .....
  8. Bill Vajk

    Bill Vajk Guest

    The simple fact that you ask that question is a
    clear indication you have no ideal regarding
    electrical distribution.

    First study matters electrical, then make a
    proposal if you think, once you know something
    about the subject, there may be a valid reason
    to make any change.
  9. Why don't you learn how the system works and why. See the following site.

    There is a good reason why we use high voltage ac to transmit electrical
    power. Learn the physics, Learn the technology.

    And stop being a schmuck.

    Bob Kolker
  10. Don Libby

    Don Libby Guest

    Very long distance powerlines too, IIRC, like the one implicated
    in a Big California Blackout a few years back.

  11. Uncle Al

    Uncle Al Guest

    Long haul lines must be DC. If you are located near a node at the
    other end you don't get anything. OTOH, typical long haul voltages
    are 500 kV to a megavolt or more to drop IR losses. The solid state
    modules that smooth it to DC on one end or chop it back to AC on the
    other are nearly a story tall with a hefty diameter.

    Uncle Al had a degreed acquaintance who went to work at LA power and
    water. During the tour he pointed up at narrow black ducting that
    threaded everywhere just above head level and asked what it did.
    Wasn't ducting as it turns out. It was naked solid copper busbar; the
    black was dust cooked by ozone and whatnot from the field, and "please
    don't try to touch it."

    Dave did chlorination oversight. He like the idea of maybe getting
    away with his life if something went sour.
  12. Steve Spence

    Steve Spence Guest

    so you think that the only reason to use ac instead of dc is the ease in
    stepping it up and down? shucks, a dc to dc converter can do that. that's
    how we run 12 vdc gadgets in cars from a 144v pack.

    there is no difference in efficiency between 110vdc and 110vac. deliver
    110vdc to the outlets, and use a dc to dc converter to run 12vdc appliances.
  13. Steve Spence

    Steve Spence Guest

    I'm not suggesting a change. I just know quite a bit about using dc. We do a
    lot of it in EV's, rv's, and off grid homes. a lot of folks have big
    misunderstandings about dc. DC is used in some high voltage distribution
  14. Steve Spence

    Steve Spence Guest

    yep, a good site for newbies.

    how about a site with a bit more meat for us electronics guys ......

    I prefer 48vdc in my house, but I don't need a grid to give it to me.
  15. Bill Vajk

    Bill Vajk Guest

    I'm sure that if you look a bit you can find out
    plenty about the deadliness of the old 32Vdc farm

    One of the points in your first post on this subject
    was about life safety. 48Vdc isn't.
  16. In sci.physics, Mark Thorson
    Conversion from the 110VAC/60Hz system we have as our
    infrastructure, while somewhat desirable in light of
    the aforementioned medical accident, will be extremely
    expensive. For starters, it's not 110VAC everywhere
    (that's only at the home); the generator plant runs at
    about 26,000 volts. Also, every generator would have
    to be rebuilt as the rotor speeds would be different --
    or rewound, as the frequency would be different if the
    rotor speed is left as is (I'm not sure one can change
    the rotor speed very effectively on a water turbine unit,
    for example). Transformers, which are carefully engineered
    to handle certain currents and voltages, will have to be
    rewound or completely rebuilt. And of course all consumer
    equipment will require rewriting or replacement -- or one
    can buy a lot of power converters, resulting in some
    power loss.

    I'll admit I like the general idea of a 400 Hz system
    but the hum from such a system may get very irritating
    (60 Hz hum is irritating enough but at least it's
    a low hum). Think of the tone from a 440 Hz tuning
    fork to get a general idea; you'd hear that *everywhere*.
    (Presumably the Air Force, however, might have some
    ideas on how to mitigate that problem. The 60 Hz hum
    one hears is primarily from harmonics.)

    Tower voltages are high to reduce losses from current while
    the electricity is traveling long distances. Ohm's Law:
    P = E^2/R; since R is fixed (barring such things as skin
    effect) it behooves us to make E as high as possible,
    consistent with other issues (e.g., ionization of the
    atmosphere -- arcing). At the destination, step-down
    transformers can be used with AC; DC has no such option.

    There is a problem with solar power, although that may
    be fixed at some point with newer technology; a solar
    cell is essentially a sheet of glass (SiO2) which needs
    to be melted at a high temperature during fabrication.
    The energy used during this process takes years to recoup
    (and is probably reflected in part in the cost of the unit
    during initial install).

    Some simpler options may be available for those
    appropriately located; one that comes to mind is a simple
    glass or plastic greenhouse, attached to the side of
    the house, with an appropriate fan and good insulation.
    While this cannot completely replace the heater it may
    reduce the load on it. In the summer one can remove the
    windows and replace them with screening, perhaps.

    The problem with glass is the same for solar cells, though.
    (A pity since it's so nice and transparent. :) ) However,
    it's simpler to construct although I'm not all that
    knowledgeable about how to reduce condensation on the
    inside of the glass.

    I'll admit I have no idea how to fix the power grid, but
    complete replacement would, again, be a very expensive

    I'm also curious how difficult it would be to set up
    a solar-powered steam turbine. :) (One assumes a
    possibly-movable metal frame on the roof funnelling the
    light via a reflective shroud into a pipe with a fluid,
    heating the fluid. Of course one has to occasionally go
    up there and clean the equipment.)
  17. In sci.physics, Sam Wormley
    [snip interesting but slightly impractical suggestions for brevity]
    An interesting thought, that, but now I wonder which is
    worse, pollutant-wise: the transportation of electricity
    over long distances, or the transportation of natural
    gas, gasoline, diesel, or kerosene over long distances.
    (The suggested unit runs on natual gas. However, I have
    problems with natural gas, mostly because we're having a
    bit of a shortage. Natural gas requires pumping to keep
    it under pressure, presumably; gasoline, diesel, and
    kerosene are, AFAIK, transported via large tanker trucks.)

    The nice thing about this unit: the internal wiring of the
    home is exactly the same.
  18. "The Ghost In The Machine"
    Besides all the other problems, sounds like a recipe for
    mass population deafness--the long-term medical costs to
    society might be stupendous! :) Why not just solve all the
    problems by building a decent transmission system with
    _proper_ protocols? Time to stop being penny-wise and pound
    foolish-at least wrt quality of life -- someone recently
    said we are the only superpower in the world with a third
    world power grid system --let's add a few more backup
    generation plants at critical nodes to help the network out
    too (all new funding for all this crap is presently tied up
    in political squabbles I believe.) We can fix the
    system--have Big Blue et al. design the network and
    failsafes this time--in this new age of "the rise of the
    machines" have the computers help us instead of hurt us with
    protocols designed by smart folks instead of Dumbos--uh,
    wasn't all this math and stuff worked out in the 5 decades
    of math and physics since the '50s...even without
    computers...go back to the game thy etc. lit. or ask that
    genius who won the Economics Nobel; he'll work it all out.
    And if we have to pay some small price to constantly
    maintain a slightly higher power generation capacity so be
    it--it will be worth it, particularly when the terrorists
    come to call now that they know our vulnerabilities! We have
    the technology and a workable current system--we can rebuild
    it even better! ...tonyC
  19. Guest

    Ahh, that's not the main problem.
    It has little to do with "penny-wise and pound foolish" and a hell of
    a lot to do with enviro-idiocy"
    Ahh, here is the rub.

    No matter how smart the transmission system is, it cannot work
    miracles. It needs a sufficient reserve capacity behind it. Now,
    check the numbers from the last few decades and observe how the excess
    generation capacity keeps shrinking. And no, this is not a matter of
    being "penny-wise and pound stupid" ("Beeh, beeh, evil corporations
    bad, evil corporations bad"), it is a matter of the public strenuosly
    objecting to the construction of every power plant and every
    transmission line. So, eventually, the public gets what it deserves
    ("who, me? Me, wrong? Me, the voter" to paraphrase P.J O'Rourke).

    In order to deal with problems properly, you've to diagnose problems
    properly, first. Seeking sacrificial lambs may be emotionally
    satisfying but it does little to address the issues.

    Mati Meron | "When you argue with a fool,
    | chances are he is doing just the same"
  20. Guest

    It hasn't helped to force the biz into an isolated futures
    market either. I'm not saying that this is a physical cause;
    I'm saying that it redirects attention.
    No, shit.
    Even thought New England power managed to squeak by, around here
    the "voter" was promised a ridiculous low cost in order to implement
    the split of power distribution and generation. How the hell are
    these companies going to do development? They're barely able to
    fund maintenance.
    Meanwhile, California fiddles while power generation burns.


    Subtract a hundred and four for e-mail.
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