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What frequency(s) is the electromagnetic radiation from high voltage power lines?

Discussion in 'Electronic Basics' started by little billy, Jun 29, 2004.

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  1. little billy

    little billy Guest

    What frequency(s) is the electromagnetic radiation
    from high voltage power lines?

    Is there an instrument that can detect underground
    high voltage lines ?
     
  2. Don Bruder

    Don Bruder Guest

    Depends on what country you're in. Here in the US, it *SHOULD* be 60Hz,
    although it may "sag" a little from time to time, and there may be
    harmonics. In the UK and most (all?) of Europe, they run 50Hz AC. Those
    are your "base" points to start looking for emissions - nothing says
    there can't be other schemes used in other places.

    Yes, "line hunters" are available that will spot underground lines. Like
    everythign, I'm sure there are the ones that are lousy, and the ones tat
    are superb at it, but don't ask me to distinguish between the two
    without a WHOLE LOT more info and some "hands-on" playing with them.
     
  3. Rick

    Rick Guest

    You probably don't want to detect "electromagnetic radiation" at 60hz, since you
    need a really long antenna to recieve 60hz electromagnetic radiation...the
    wavelength at that frequency is around 5000km. Most anything you detect in the
    60hz realm is near field (inductive).
     
  4. Clinton

    Clinton Guest

    The safest way to find underground high voltage lines is to call the power
    company.
     
  5. Bob Masta

    Bob Masta Guest

    In the USA, the power grid is divided into several regions.
    Within each the frequency is 60 Hz. But there are also
    interties between regions, and since it would be too
    difficult to keep all the regions in perfect sync, the interties
    are DC. When I first found out about this I couldn't
    believe it, but they actually have to go through conversion
    processes at both ends. Have to wonder how they do
    this at a gazillion amps and keep the losses from
    melting the equipment!


    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
     
  6. Gordon Youd

    Gordon Youd Guest

    If you want to find overhead powerlines use a kite.
     
  7. L. Fiar

    L. Fiar Guest

    Assuming that BT really is your ISP, I suspect you are here in the UK... The
    mains supply is 50Hz.
     
  8. little billy

    little billy Guest

    This does not make any sense at all. Everyone here
    says that the the requency is 50 Hz. I know the
    electricity works at 50 Hz, this does not mean that
    the electromagnetic waves of high power cable lines
    are 50 Hz. For example, whenever I drive near high
    voltage lines my am radio goes all haywire. This means
    that at least some of the radiation is at 100 - 1600
    KILO Hertz. I can't believe someone suggested to build
    a 5000 km antenna to test these waves, I assume he was
    making some sort of joke of my question. Obviously, any
    detector should be smart enough to use a detection
    method which doesn't involve builing a 5000 km antenna.
     
  9. Dave Holford

    Dave Holford Guest

    If you are getting noise on your broadcast radio why not use a small
    portable receiver and find the place where the noise is strongest -
    should put you in the general area.

    Dave
     

  10. He's talking about the frequency of the radiation itself, guys. If you turn
    a red light on and off at 60 Hz, that doesn't mean the light is radiating at
    50 Hz.

    Don
     
  11. Bob Myers

    Bob Myers Guest

    Not at all - all that means is that sufficiently strong 50 Hz
    fields are capable of inducing noise in your radio. Surely
    you don't believe that ONLY "100-1600 kHz" fields are
    capable of affecting your radio, do you?

    The frequency of the AC power is 50 Hz (in the UK), and
    therefore the fields around the lines are also 50 Hz, and
    essentially ONLY 50 Hz.

    Bob M.
     
  12. Rich Grise

    Rich Grise Guest

    If the radio's any good, they are.
    This is not accurate, if there's a fault in the line of
    some kind, like a corona. Even dirty insulators can do it.
    There's a nonlinear conductor of some kind in the circuit,
    and it makes harmonics every 50 (or 60) Hz up to as high
    as you can detect.

    If your AM radio gets interfered with, tell the power company.
    They'll want to know, because there's a loss in their line
    somewhere.

    And if you don't believe me, ask _them!_

    Cheers!
    Rich
     
  13. Think about it- what your radio is picking up is not the 50 hz
    electrical field. It can't. What you are in fact detecting is noise from
    arcing losses, or from non-linear elements in a transformer, or any number
    of other things.
    Any time you rapidly switch something, from tiny arcing losses or from
    corrosion on a contact, or even from a simple square wave, you generate RF
    harmonics. That is what you are picking up. You would need an antenna that
    was about 6000 km in length (or some nice handy multiple or fraction of
    that) to effectively pick up 50 hz electromagnetic waves.

    Cheers!

    Sir Charles W. Shults III, K. B. B.
    Xenotech Research
    321-206-1840
     
  14. Don Kelly

    Don Kelly Guest

    -----------
    A major couse of RF interference from power lines is due to corona
    discharges due to high fields near the conductors. Broad frequency noise
    from audio to TV frequencies can occur. Sometimes it is due to corona
    discharges at points such as the ends of tie wires on insulators, sometimes
    loose connections on hardware in regions of high field intensity, sometimes
    due to contamination on insulator surfaces. Often low voltage (33KV or so)
    lines are worse than EHV (330KV or more) are worse culprits (sharp points).
    On High voltage lines, contamination of insulators, nicks or crap on the
    conductors, etc are more prevalent.
    In areas where this is a problem, the utility is (or should be) responsible
    for reduction/mitigation of the problem.
    Normal 50/60 Hz will not be a problem. Harmonics of 50/60 Hz that may exist
    will also not be a problem. (25th harmonic of 60 Hz is at 1500Hz and will be
    extremely small as well as not being in the "RF" range).
     
  15. Chris Hodges

    Chris Hodges Guest

    And if you did pick up 50Hz (which is easy to do accidentally in the
    near field) it's AF and you'd hear it as a low hum.

    Chris
     
  16. Ah, right you are. Thanks.

    Don
     
  17. Bob Myers

    Bob Myers Guest

    But his question comes from noise heard on an AM
    radio when in the presence of power lines. Since
    those AREN'T switched (at least, not often! :)), the
    noise in question is almost certainly from induced noise
    currents at the power-line frequency.

    Bob M.
     
  18. Bob Myers

    Bob Myers Guest

    Very, very few radios (or any other consumer electronics)
    are completely immune to frequencies outside of the band
    of intended reception. Wanna compare EMI susceptibility
    horror stories? :)
    And hence the word "essentially." But if you're talking
    about the fields you will most commonly encounter, and
    the relative power level of these fields, the top of the lists
    will always be a big fat magnetic field at the power
    frequency.

    Agreed, IF the circumstances are such that would suggest
    corona discharge as the culprit. That did not seem to be
    the case here.

    Bob M.
     
  19. It's easy. Just use a lot of insulation. It's only a half a megavolt
    DC at 2000 amps. :-O

    http://205.243.100.155/frames/longarc.htm#500_kV_Switch

    Check this out. This is 1.5MB, so it may take awhile. If the above
    doesn't work, then go to www.teslamania.com and use the menues Big Arcs
    'N' Sparks.
     
  20. Those aluminaized mylar birthday balloons work much better. One landed
    across the 12KV line where I live, took out the whole neighborhood for
    over 8 hours. Just that silly little balloon burned out the transformer
    and melted the 10 gage aluminum wire.

    [snip]
     
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