Transmission lines have EM fields around them due to the high amount of current. Do these fields affect transmission towers (metal or otherwise)? If so, would it be possible to estimate the current flowing through the lines by measuring EM fields at the base of a transmission tower?
Electronic – Do transmission lines induce electric or magnetic fields in towers
inductancetransmission line
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“Persons were charged with stealing electricity by placing a large coil, somehow, near high voltage AC transmission lines.”
Is this feasible or was it perhaps an April fool’s article that I swallowed hook line and sinker in my youthful naivety.
Entirely feasible.
Farmers were occasionally charged with power theft in this country (New zealand) in the past. I haven;'t heard of a case in a decade or few - maybe they are getting cleverer at it :-).
This is the same principle as used for "IPT" / "Inductive Power Transfer as seen in phone chargers, industrial monorail powering, electric vehicle charging and much more.
I started to say that if the pickup coil was symmetrical with respect to two phases that were perfectly balanced that you'd get zero pickup, and then suddenly realised that I've always done IPT with essentially a single phase, and that with a 3 phase system with 120 degrees phase separation you should get the advantage of the full load current even if the two phases were fully balanced.
You are essentially getting fields produced by the current, not the voltage, and the voltage is essentially irrelevant as long as you observe the normal conventions that apply to any other dealing with xxx kV.
Energy Harvesting from Electromagnetic Energy Radiating from AC Power Lines - FAR more energy can be obtained than they achieve.
Worked example - I suspect some of the conclusions are suspect A Solution to the RWP for Exam 1 - Stealing Power
Low technical content - high relevance
Directly relevant but low technical value Electromagnetic Harvesters: Free Lunch or Theft!
Several related stack exchange questions with variably useful content.
How would an electric company detect wireless theft of electricity?
Stealing energy from radio towers or power lines
Online vehicle transfer - I do not have access to this paper but it is probably at least relevant as it will have examples of dual linear conductors and a pickup coil.
Related:
Capacitive - but impressive:
You can determine the voltage imposed on the wires. This is done by looking at the insulators holding the wires off the tower. The more discs, the higher the voltage. Those look like pretty high voltage, for long distance distribution.
However, voltage has nothing to do with the electromagnetic fields. That is determined by the current in the wires. That's not so easy to determine.
However, since you are interested in the electromagnetic fields at your location, the power company has an EMF meter they use to measure such a thing. I don't know the arrangements for this, but call them and ask. They came out and did a survey at my house when I sold it, so I know the service is available. I don't recall having to pay for it.
Best Answer
To some extent.
You have electric field simply because of the voltage on the wire. This static electricity has an effect on nearby objects. Air ionization, attraction forces, etc.
The magnetic field induces currents (and voltages) in conductive structures. BUT, the effect on towers will be minimal simply because power lines and comms towers are perpendicular to each other. So pretty much no inductive interaction comes into play.
What's more, such structures are always grounded. So there's no voltage on them. The only thing you may be able to detect on the tower is its magnetic field originating from the 50Hz current flowing up and down the structure. However I said this current will be minimal, so yeah.
If you'd be able to measure currents in power lines from any of that, I have no idea.