What is Power lines: Definition and 47 Discussions

Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines which facilitate this movement are known as a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is part of electricity delivery, known as the electrical grid.
Efficient long-distance transmission of electric power requires high voltages. This reduces the losses produced by heavy current. Transmission lines mostly use high-voltage AC (alternating current), but an important class of transmission line uses high voltage direct current. The voltage level is changed with transformers, stepping up the voltage for transmission, then reducing voltage for local distribution and then use by customers.
A wide area synchronous grid, also known as an "interconnection" in North America, directly connects many generators delivering AC power with the same relative frequency to many consumers. For example, there are four major interconnections in North America (the Western Interconnection, the Eastern Interconnection, the Quebec Interconnection and the Electric Reliability Council of Texas (ERCOT) grid). In Europe one large grid connects most of continental Europe.
Historically, transmission and distribution lines were often owned by the same company, but starting in the 1990s, many countries have liberalized the regulation of the electricity market in ways that have led to the separation of the electricity transmission business from the distribution business.

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  1. Trikenstein

    [SOLVED] Cone suspended on power line, between 2 poles

    Hi, The photo shows some objects suspended on a power lines near an airfield Here is the location of those objects on a map: The 3 pink circles are the oranges balls in the photo. Which seem to be Aerial Marker Balls. QUESTION: The pink triangle is the cone shown in the photo. What is...
  2. russ_watters

    PFAS and Power Lines Cause Cancer?

    Here's an article(labeled as opinion) I just read from CNN: https://www.cnn.com/2023/08/16/opinions/chemicals-in-clothes-harmful-health-wicker/index.html This OP is only a starting point; I intend to look into the issue more deeply. But from what I see, this article (not unique these days) is...
  3. dlgoff

    Underground transmission power lines

    @anorlunda suggested I start a new thread about this: See: https://www.physicsforums.com/threads/grim-day-on-the-texas-power-grid.999764/post-6521013
  4. Raffallo

    Calculate the max current for a powerline

    Hello All! I'm new in this forum, so if I select wrong subject or something then sorry. I'm very, very far from physic, so I need your help. In work, I have to calculate max current for HV power line. As input have conductor temperature [*C] and material parameters (the resistance in ohm of the...
  5. J

    Why don't birds get shocked on power lines?

    I know the answer, because they are not grounded and do not complete any circut, but I have a different analysis that I would like to explore. First, why do you need a closed circuit? Because if you have a battery pushing current along a wire that ends, electrons will accumulate at the end of...
  6. DrClaude

    Power lines connecting to the ground

    This is going to be a very basic question, but something that has bothered me for a while. It was triggered again by this thread from @OmCheeto: https://www.physicsforums.com/threads/new-deccan-trap-turns-out-to-be-downed-power-line.970313/ Why is it that when a power line is downed, there is...
  7. TechTree

    Computer What device would I need to send data over power lines?

    Hello, I'm trying to send binary data over the power lines to a microcontroller, which triggers a relay turning on a light. I was wondering what kind of device would I need to use to achieve this? And how would I connect it up to the microcontroller? I'm fairly new to this, so if someone could...
  8. entropy1

    How does a force get transmitted through power lines?

    Why does a turbine in an energy plant experience more resistance if the electrical load on the other end increases (electrical resistance decreases)? What I don't understand is how the force that drives for instance a washing machine gets through the power lines that don't seem to experience...
  9. M

    Health Risks Living Near Power Lines

    Hello Please give me some advice on a lot my wife and 2 kids are thinking on building our home on in SC. It will be located next to a large power line right of way. Its near a lake so we have those big metal towers. I'd say the nearest tower from my house will be like 50 to 75 yards. I took a...
  10. astroscout

    High Voltage Discharges or Explosions from Powerlines -- why these colors?

    Hi...Here is a GIF of some electrical explosions that I recorded with my full spectrum camera. These power lines supply power to a neighboring county so it didn't affect my area. In the upper atmosphere we see something similar in Transient Luminous Events (TLEs). In the case of the blue in Blue...
  11. FlimFlam

    Grass Death Under Power Lines: EMF's a Factor?

    So I was messing with the induction from power lines and fluorescent bulbs, and I noticed all the plants under the power lines were dead but plants around it were fine. Do EMF's have something to do with this?
  12. G

    Identifying overhead power lines (esp. UK)

    Has anyone got a good link to a guide to UK power lines? I hate looking up and not knowing what's there. For example, my house has several poles leading to it, strung with one live 240V and one neutral, the latter being tapped to Earth at each pole. What if there are two lines, strung...
  13. T

    Question about Transmission Line Losses

    Hi there, If I'm using the equation P_loss = P^2 * R / V^2 to calculation the power lost on a cable, where R = p(resistivity) * L(length) / A(cross sectional area), then how long is this power loss for exactly? Thanks, Sydney
  14. C

    Confusion with regards to power lines and the power lost

    Ok, so the title was pretty vague, I'm not sure how to succinctly describe the confusion. Anyway, so I've learned that the power lost is P=I2R, and so by increasing the voltage, as P=VI and is constant, the current will be lowered, and thus the power lost will decrease. I'm confused about a...
  15. yabb dabba do

    Modeling E and B field of power lines

    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...
  16. M

    Aluminium vs Copper in power lines

    Hi, I have a question concerning the use of aluminium in power lines. I know that it's lighter than copper and thus cheaper, which is the main reason we prefer it above copper. But in fact alumunium has a lower conductivity than copper. Why is it then that one kg of aluminium can carry twice...
  17. rumborak

    Could one build "thermal power lines"?

    It just occurred to me that akin to electric power lines, which in the end just connect a voltage differential over a long distance and facilitate power exchange between the two end points, one could build "thermal power lines". That is, a well-insulated cable that internally consists of a...
  18. Gerry Rzeppa

    Electron Re-arrangement and Flow in Power Lines

    I've been doing some bedtime reading in Chabay & Sherwood's Matter & Interactions textbook (https://www.amazon.com/gp/product/0470503475/?tag=pfamazon01-20) and have come across some interesting tidbits. Here they are: I've always pictured electrons pushing each other through a wire, kind of...
  19. S

    Overhead power lines wires and strings deviation

    Hello to all of you. I have the following case to solve. I have three overhead power line towers. The first and the third are with tension insulator strings, and the second is with suspension insulator string. During the design process i noticed that the second tower is located incorrectly and...
  20. neduet

    Selecting conductors for transmission line 132kv 100MW 95km

    Hello dears i want to know which is best for 132kv transmission line. advantages and disadvantages as in prectical use. but also consider economical factor wisely . what you chose if you are in my place... ACSR Conventional AAAC ( All Aluminium Alloy Conductors ) ACCC Aluminum Conductor...
  21. A

    What is the Maximum Magnetic Field Under Overhead Power Lines?

    Homework Statement You want to get an idea of the magnitude of magnetic fields produced by overhead power lines. You estimate that the two wires run about 30 m above the ground and about 2.9 m apart. A call to the local power company provides the information that the lines operate at 10 kV...
  22. skepticwulf

    Importance of the frequency of AC mains power lines

    From textbook: "In much of the world (Europe, Australia, Asia) the rms voltage is 240 V, so the peak voltage is 340 V. The line voltage can vary, depending on the total load; the frequency of 60 Hz or 50 Hz, however, remains extremely steady" Why is it so important to keep it steady? what...
  23. Roynish

    Working out power loss in power lines: Multiple wires

    Hey everyone, This is quite a simple question, I think I'm just getting confused. 1. Homework Statement Given Data: Merlin: Resistance: 2 Ω / km, Maximum Current: 519 Pelican: Resistance: 1.5Ω/km, Maximum Current: 646 Penguin: Resistance: 4 Ω/km, Maximum Current: 357 Sparrow: Resistance...
  24. F

    Power Dissipation along power lines and Resistance value

    Hello Forum, It is well known that the electrical power dissipated (in the form of heat) by a resistor of resistance R connected to a battery of voltage V is: P_diss = (V^2)/ R or equivalently P= (I^2)*(R) Clearly the smaller the resistance R, the more the dissipated power because R is at...
  25. K

    Power lines from an electrically charged ball

    Homework Statement A conductive ball of diameter 0.4 [m] is charged equally with a concentration of \sigma=8 [micro-coulon/m^2]. What's the total number of electric field power lines, N, that extrude from the ball Homework Equations The electric field near a conductor is like in a capacitor...
  26. T

    P = VI = (281V)(3.75A) = 1054 W

    Homework Statement A small power plant produces a voltage of 6.0 kV and 150 A. The voltage is stepped up to 240 kV by the transformer before it is transmitted to a substation. The resistance of the transmission line between the power plants and the substation is 75 Ohms. What percentage...
  27. A

    Electric current - High voltage power lines buzzing

    Electric current -- High voltage power lines buzzing Question: High voltage power lines string along roads often give off a faint buzzing sound. Use what you know about the motor principle to explain the source buzzing. ok, so i have no idea how to approach this. I've never heard...
  28. R

    Faraday Cage Applied to Power Lines to Negate Field Interference

    Hello learned Engineers, Physicists, and people more useful than myself: Thank you in advance for reading. I would like to submit a more educated proposal to a utility company for a method that would allow it to install 500 kilovolt renewable power transmission lines through many residential...
  29. Lavid2002

    Quick question about power lines and E=IxR

    Ok so I have read that power lines carry very high voltage to minimize loss through resistance, but when I take a look at the formula E=IxR E=Voltage I=Current R=Resistance Divide both sides to get E/I=R To minimize R we should make the numerator of the quotient smaller, and the...
  30. I

    Completing the circuit in power lines

    I am having trouble understanding how a circuit is completed from the AC power plants over the high voltage power lines. In order for current to flow there must be a "neutral" conductor. I can only conclude that the ground is used somehow to make this current flow. In contrast, the wires...
  31. V

    Medical Is Living Near Underground Power Lines Making Me Sick?

    I have a property with a 3 phase underground power line. The power line doesn't go near the house but happens to pass directly underneath the shed, which is in the form of a sea container. Whenever I'm working inside the container, I feel sick. The symptoms are similar to those described by...
  32. S

    Why do birds on power lines not act as resistors?

    Imagine a circuit with a cell and no resistors. If I connected a resistor to two points in the circuit, would a current flow through it? Does a bird on a power line act like this? Why does it not get electrocuted? Sorry if this is a stupid question - I'm terrible with electronics! :blushing:
  33. W

    Power lines over canyons. How do they do it?

    How are power lines connected over canyons? Are they simply laid out on the canyon floor and then hoisted up and stretched to the towers? Just wondering. Thanks.
  34. BobG

    Electrocutions: Downed power lines kill 3; survivors not shocked at all

    Downed power line kills 3 in San Bernardino I wonder if there's a special place in hell for those that make puns at the expense of people dying in a horrible accident.
  35. P

    Magnetic Field due to Power Lines

    Homework Statement You want to get an idea of the magnitude of magnetic fields produced by overhead power lines. You estimate that a transmission wire is about 25 m above the ground. The local power company tells you that the line operates a 12 kV and provide a maximum of 47 MW to the local...
  36. T

    How Does Current Return to the Source Through the Ground in AC Power Lines?

    So i know the whole picture starting from power from the generating plants that go all the way to our homes..and the ground serves as a return path to complete the circuit..What i don't get is...how does that current find its way back to the source through ground?..is the source somehow...
  37. C

    Ac voltage drop accross power lines

    so the reason why alternating current is used to deliver energy to households is because for a given wire, the voltage drop is always less with ac rather than dc right? but when i calculate the voltage drop it coumes out to be the same! v=IR R=P(length of wire)/(cross section area of wire) i...
  38. JJBladester

    Working on high voltage power lines

    Homework Statement We know that current will flow whenever there is a potential difference. Sometimes when there are problems with high voltage lines - workers must work on them 'live' (not shut down). How do the workers manage to work on the wires without getting electrocuted by the high...
  39. S

    Current Transmission in power lines

    If the electric field at a point drops off in intensity as the inverse ratio of the square of distance from the source, how do power lines manage to carry current through such large distances?
  40. H

    Math for why voltage is stepped-up in power lines?

    I've long understood that voltage is stepped-up in power t-lines to decrease losses, however, I've never really understood the math reasoning behind it. Isn't P = V^2/R the same as P = I^2*R? If so, it seems that either increasing V or increasing I would invoke the same losses... Could...
  41. B

    How Close Do You Need to Be to High Voltage Power Lines to Induce Current?

    I have a physics question that I'm hoping someone has enough free time and is intrigued enough to figure out for me! My sister just bought a house which is near some high voltage power lines. I've heard that people living near these types of lines can sometimes induce a current in wires...
  42. I

    Medical Health Risks Associated with Living Near High-Voltage Power Lines

    I've never found any conclusive evidence suggesting that it does. Have there been any independant studies conducted?
  43. M

    Force on 2 Power Lines: Why Does it Repel?

    Why is it that two power lines carrying anti parallel currents exert force away from each other as oppose to to each other?
  44. I

    Connecting AC Power Lines: Understanding Wattage & Current

    What is the proper way to connect several ac power lines into one line. So let's say if you had 20 lines and each had a 10 volts and 1 amp of power so 10 watts AC. When connecting them into one line would you have 200 watts. Also with it being alternating what would happen when the current is in...
  45. E

    Magnetic fields from power lines

    Homework Statement Well I just want to make sure I am right on this one. The question is how to steal electricity by placing a coil near a power line that carries alternating current in which the current varies sinusoidally. A.) For a single wire how should the coil be oriented to induce the...
  46. A

    Why dont birds get electocuted when they are on power lines?

    [b]3. The Attempt at a Solution [/b Maybe because charge passes through the powerlines and doesn't stay at one spot?
  47. D

    Understanding Power Line Safety: Workers and Birds on Transmission Lines

    when workers work on transimssion lines, they first use a rod to energerize themselves to avoid getting shock. But how come a bird doesn't get shock when it sits on the line without safely energizing itself first? Does current from transmission line flow to the helicopter when it is in the...