wtm@neoucom.UUCP (Bill Mayhew) (11/30/89)
As part of the obligatory stuff necessary to get through undergrad EE school, I recall taking a course named, "energy conversions," that dealt with giant electric motors, 100 KVa transformers and ower transmission lines. One of the readings was on transmission lines. It discussed that power disspated in the space surrounding the lines is substantial, and field strenghths can be several hunderd volts per meter in the close environs. The article mentioned that cows in the vicinty of transmission lines tend to line up with the major axis of their bodies parallel to the tranmission line. The feeling (literally??) was that it was more comfortable for the cows to line up that way, as their bodies would subtend a smaller number of isopotential field lines, and thus the impressed voltage on the cow would be smaller. As far as living close to an AC transmission line goes, I'd worry more about what unknown thing it might do to me, rather than anything that might happen to my computer! There have been some articles that border on pseudoscience circulating lately that claim a correlation of cancer incidence an living close to a large source of 60 Hz H field! You read that right. The author cliamed that 60 Hz magnetic fields correlate to incidence of lukemia. His reasoning was that people that lived close to the head end of a power line where the currents in the line are higher suffered more cancers than people that lived near the end. What the article did not mention was if other causitive factors such as people that live near the head end might be exposed to higher levels of emissions from the utility or other industry were accounted for. The sample population was also relatively small. The earth's magnetic field (though virtually steady-state) can be measured in Tesla, while the H field more than a few hundred feet from a transmission line would be fractional Webers/m^2. Why is a 60 Hz alternating field more deleterious than a steady state field?... One theory was that the alternating field disrupts RNA durring cell division. Why wouldn't the earth's field be a problem? The RNA in the cell is moving around, so it is going to be cutting field lines of the earth's feild which are much stronger than any field from the power lines nearby. Perhaps, the original poster was just trying to whip up some network fury? It wouldn't surpirse me to see several hundred articles on the subject. Bill wtm@neoucom.edu
jans@tekgvs.LABS.TEK.COM (Jan Steinman) (12/02/89)
I g g g grew up grew up up quite near high t t t ten tension tension lines, and I t t t turned out turned out out okay okay! Seriously, one thing that left a big impression was being up in my tree house, looking over the fields at the quite noticeable "bump" running directly under the lines where all the crops grew bigger. My dad always said he wouldn't make any money farming if it weren't for those power lines! The latest Science News reported on research that showed statistical correlation between leukemia and telephone linemen. One interesting point was that the researcher had been a skeptic, and had in fact produced an earlier study sponsored by the electrical power industry that showed no correlation! Details on request, but first see if your library stocks Science News. Jan Steinman - N7JDB Tektronix Electronic Systems Laboratory Box 500, MS 50-370, Beaverton, OR 97077 (w)503/627-5881 (h)503/657-7703
sewilco@datapg.MN.ORG (Scot E Wilcoxon) (12/03/89)
In article <1845@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: ... >There have been some articles that border on pseudoscience >... people that lived >close to the head end of a power line where the currents in the >line are higher suffered more cancers than people that lived near >the end. ... Another recent study found that the leukemia rate near nuclear plants was the same as near places where nuclear plants were proposed but were never built. This suggests that something about a location which is a good site for a nuclear plant also makes it a good location for leukemia, or locations unsuitable for one are also unsuitable for the other. -- Scot E. Wilcoxon sewilco@DataPg.MN.ORG {amdahl|hpda}!bungia!datapg!sewilco Data Progress UNIX masts & rigging +1 612-825-2607 uunet!datapg!sewilco I'm just reversing entropy while waiting for the Big Crunch.
jack@swlabs.UUCP (Jack Bonn) (12/05/89)
In article <1845@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: >One of the readings was on transmission lines. It discussed that >power disspated in the space surrounding the lines is substantial, >and field strenghths can be several hunderd volts per meter in the >close environs. I was wondering: what ever happened to the use of high voltage DC for power transmission? I understood that the high voltage inverters needed were technologically feasible, yet I've heard very little of this since. It seems that this could reduce the varying magnetic field, thereby reducing the voltage induced in objects nearby. Of course, this would raise the system's efficiency as well. Mr. DC himself, Thomas Edison, would be proud. -- Jack Bonn, KA1SMW, <> Software Labs, Ltd, Box 451, Easton CT 06612 uunet!swlabs!jack (UUCP) jack%swlabs.uucp@uunet.uu.net (INTERNET)
torkil@psivax.UUCP (Torkil Hammer) (12/05/89)
In article <6446@tekgvs.LABS.TEK.COM> jans@tekgvs.LABS.TEK.COM (Jan Steinman) writes:
#
#Seriously, one thing that left a big impression was being up in my tree house,
#looking over the fields at the quite noticeable "bump" running directly under
#the lines where all the crops grew bigger.
The explanation I read about 30 years ago was in terms of metals leaching
out of the wires, specifically zinc, and droppings from resting birds, and
the scarecrow effect the buzzing has on various munchers.
Is it still good?
#The latest Science News reported on research that showed statistical
#correlation between leukemia and telephone linemen. One interesting point was
The most convincing explanation I have seen is in terms of PCB and
other chemicals used where linemen go. These chemicals are no longer
used but there is a lot of old equipment out there.henry@utzoo.uucp (Henry Spencer) (12/06/89)
In article <8902@swlabs.UUCP> jack@swlabs.UUCP (Jack Bonn) writes: >I was wondering: what ever happened to the use of high voltage DC for >power transmission? ... It's done here and there, usually for some special reason like making a connection between two power grids that aren't synchronized to each other. There is enough inconvenience involved in converting from AC to DC and back that there usually needs to be a good reason. -- Mars can wait: we've barely | Henry Spencer at U of Toronto Zoology started exploring the Moon. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
ems@Apple.COM (Mike Smith) (12/06/89)
In article <2965@psivax.UUCP> torkil@psivax.UUCP (Torkil Hammer) writes: >In article <6446@tekgvs.LABS.TEK.COM> jans@tekgvs.LABS.TEK.COM (Jan Steinman) writes: ># >#Seriously, one thing that left a big impression was being up in my tree house, >#looking over the fields at the quite noticeable "bump" running directly under >#the lines where all the crops grew bigger. > >The explanation I read about 30 years ago was in terms of metals leaching >out of the wires, specifically zinc, and droppings from resting birds, and ^^^^ Most big wires today are aluminum, in the past they were copper. Why zinc? Electrolytically refined copper has little zinc left in it. The birds tent to congregate on the towers. Was/is there a higher growth under the tower than under the 'droop'? -- E. Michael Smith ems@apple.COM 'Whatever you can do, or dream you can, begin it. Boldness has genius, power and magic in it.' - Goethe I am not responsible nor is anyone else. Everything is disclaimed.
elliott@optilink.UUCP (Paul Elliott x225) (12/07/89)
> In article <6446@tekgvs.LABS.TEK.COM> jans@tekgvs.LABS.TEK.COM (Jan Steinman) writes: >The latest Science News reported on research that showed statistical >correlation between leukemia and telephone linemen.[...] I just saw a newspaper item re: this report. I found it interesting that the absolute number of cases was 6 or 7 (as I recall). I don't remember if the sample size was mentioned. Has anyone seen a statistical analysis of the data (std deviation, chi-squared, etc.)? The number of cases seems pretty small to draw any strong conclusions. This is an interesting topic, but much of the reporting on it seems to have a pretty obvious socio-political axe to grind, so I remain "cautiously skeptical". -- Paul M. Elliott Optilink Corporation (707) 795-9444 {pyramid,pixar,tekbspa}!optilink!elliott "I used to think I was indecisive, but now I'm not so sure."
roy@phri.nyu.edu (Roy Smith) (12/07/89)
In article <5605@internal.Apple.COM>, ems@Apple.COM (Mike Smith) writes: > Most big wires today are aluminum Actually, most big wires today are a combination of aluminum and steel, what they call ACSR (Aluminum Conductor Steel Reinforced). It's a central strand of steel with 6 (I think) strands of similar guage aluminum wrapped around it. The aluminum carries essentially all of the current (a combination of both skin effect and the higher conductivity) and the steel provides structural strength. -- Roy Smith, Public Health Research Institute 455 First Avenue, New York, NY 10016 {att,philabs,cmcl2,rutgers,hombre}!phri!roy -or- roy@alanine.phri.nyu.edu "The connector is the network"
harrison@sunny.DAB.GE.COM (Gregory Harrison) (12/09/89)
In article <1845@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: > >The earth's magnetic field (though virtually steady-state) can be >measured in Tesla, while the H field more than a few hundred feet >from a transmission line would be fractional Webers/m^2. Why is a >60 Hz alternating field more deleterious than a steady state From memory, the Earth's magnetic field is 5 microTeslas, and since 1 Wb/m^2 is 1 T, large fractional Wb would be more powerful than 5 microT. Thus there would be more physiological effects due to the 60 Hz radiation. I also heard that anemia may be induced by 60 Hz radiation (again, from memory, no references) Greg Harrison My opinions are not intended to reflect those of GE.