Modeling E and B field of power lines

In summary: The line is modeled as a transmission line because it behaves as if there were just one wire, with no distributed impedance, and the EM fields are all averaged out. This is an approximation, and in reality there are three wires, but the approximation is accurate enough for most purposes.The three wires in a typical long distance power line are modeled as a single line with distributed impedance. The E-field links the three conductors together and so it is at right angles to the conductors. The B field of each wire is of opposite rotation, so it looks like a figure of eight, with a strong field between the wires.
  • #1
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I’m confused:

Long distance electric power lines are modeled with distributed impedance and are therefore modeled as transmission lines.

Long distance electric power lines are considered to be a two wire line (for a single phase of the electric power line anyway). What other types of transmission line could it be? (see page 5 of the following pdf for an example of the two wire line and other types of transmission line: http://www.sonoma.edu/users/f/farah...onLines/TransLine/TransmissionLinesPart_I.pdf)

Two wire transmission lines have TEM mode where electric and magnetic fields are orthogonal to each other and both are orthogonal to the direction of propagation

Long distance electric power lines have a B field which circles the power line (as per ampere’s law) and the E field is parallel to the axis of the transmission line.

So I am confused: If long distance power lines are really two wire transmission lines with TEM mode, then the E field can’t be axial and the B field can’t circle the power line. On the other hand the B field does circle the power line as per ampere’s law and the E field is axial.

(sorry for the cross post, meant to post this here)
 
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  • #2
The E-field links the two conductors together and so it is at right angles to the conductors. The B field of each wire is of opposite rotation, so it looks like a figure of eight, with a strong field between the wires.
 
  • #3
Welcome to PF.
Long distance lines are three phase. Because the directional sum of currents in the three wires is zero, and the average voltage is zero, the external EM fields away from the line all tend to cancel. The three phases make a "single line" that is modeled as a simple transmission line, quite independent of conductor count.
 

FAQ: Modeling E and B field of power lines

1. What is the purpose of modeling E and B fields of power lines?

The purpose of modeling E and B fields of power lines is to study and analyze the potential electromagnetic effects of power lines on the surrounding environment and living organisms. This is important for ensuring the safety of individuals and the environment.

2. How do you model the E and B fields of power lines?

The E and B fields of power lines can be modeled using mathematical equations and computer simulations. These models take into account the physical properties of the power lines, such as their voltage and current, as well as the surrounding environment.

3. What factors affect the E and B fields of power lines?

The E and B fields of power lines are affected by various factors, including the voltage and current of the power lines, the distance from the power lines, and the type of terrain and materials in the surrounding area.

4. Are there any regulations or guidelines for E and B fields of power lines?

Yes, there are regulations and guidelines set by organizations such as the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronics Engineers (IEEE) to ensure that the E and B fields of power lines are within safe levels for human exposure.

5. How can the results of modeling E and B fields of power lines be used?

The results of modeling E and B fields of power lines can be used to inform the design and placement of power lines, as well as to assess potential health risks and implement safety measures. They can also be used to educate the public about the potential effects of power lines on the surrounding environment and living organisms.

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