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Transmission lines in Lund, Sweden

BC Hydro transmission towers and lines in Coquitlam, British Columbia.

PG&E's Path 15 500 kV power lines in the California Central Valley.

Power lines near Helsinki, Finland

A tension tower with transposed phases carrying a power line for single phase AC traction current (110 kV, 16.67 hertz) near Bartholomä in Germany

Electric power transmission, a process in the delivery of electricity to consumers, is the bulk transfer of electrical power. Typically, power transmission is between the power plant and a substation near a populated area. Electricity distribution is the delivery from the substation to the consumers. Electric power transmission allows distant energy sources (such as hydroelectric power plants) to be connected to consumers in population centers, and may allow exploitation of low-grade fuel resources that would otherwise be too costly to transport to generating facilities. Image File history File links Portal. ... Power Line is a neoconservative blog run by three lawyers: John H. Hinderaker (Hindrocket), Scott W. Johnson (The Big Trunk) and Paul Mirengoff (Deacon). Power Line covers political and social issues from a conservative viewpoint. ... For other uses, see Power band. ... Power Grid is a multiplayer board game invented by Friedemann Friese, published by Rio Grande Games. ... Electric transmission lines, picture taken by myself. ... Electric transmission lines, picture taken by myself. ...   IPA: is a city in SkÃ¥ne in southern Sweden. ... Image File history File linksMetadata Download high resolution version (1704x2272, 1062 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Electric power transmission User:Buchanan-Hermit/photographs/coquitlam Metadata This file contains additional information, probably added from the... Image File history File linksMetadata Download high resolution version (1704x2272, 1062 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Electric power transmission User:Buchanan-Hermit/photographs/coquitlam Metadata This file contains additional information, probably added from the... This article or section does not cite its references or sources. ... This article is about Coquitlam, British Columbia. ... Image File history File linksMetadata Download high resolution version (2048x1536, 688 KB) Summary This picture was taken by me on 9/17/2005. ... Image File history File linksMetadata Download high resolution version (2048x1536, 688 KB) Summary This picture was taken by me on 9/17/2005. ... The Pacific Gas and Electric Company (PG&E) , (NYSE: PCG), is the utility that provides natural gas and electricity to most of Northern California. ... Path 15 is the name of a major north-south power transmission corridor in California. ... Official language(s) English Capital Sacramento Largest city Los Angeles Largest metro area Greater Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... This article is about Californias Central Valley. ... Image File history File linksMetadata Download high-resolution version (1920x2560, 2161 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Electric power transmission Metadata This file contains additional information, probably added from the digital camera or scanner used... Image File history File linksMetadata Download high-resolution version (1920x2560, 2161 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Electric power transmission Metadata This file contains additional information, probably added from the digital camera or scanner used... Location of Helsinki in Northern Europe Coordinates: , Country Province Region Uusimaa Sub-region Helsinki Charter 1550 Capital city 1812 Government  - City manager Jussi Pajunen Area  - City 187. ... Image File history File linksMetadata Download high-resolution version (936x1764, 672 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Electric power transmission Overhead lines Railway electrification system Electricity pylon Anchor pylon 15 kV AC Metadata This file... Image File history File linksMetadata Download high-resolution version (936x1764, 672 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Electric power transmission Overhead lines Railway electrification system Electricity pylon Anchor pylon 15 kV AC Metadata This file... For other uses, see Electricity (disambiguation). ... A power station (also power plant) is a facility for the generation of electric power. ... A 115 kV to 41. ... 11kV/400V-230V transformer in an older suburb of Wellington, New Zealand Electricity distribution is the penultimate stage in the delivery (before retail) of electricity to end users. ... Hydroelectric dam diagram The waters of Llyn Stwlan, the upper reservoir of the Ffestiniog Pumped-Storage Scheme in north Wales, can just be glimpsed on the right. ...

Due to the large amount of power involved, transmission normally takes place at high voltage (110 kV or above). Electricity is usually transmitted over long distance through overhead power transmission lines. Underground power transmission is used only in densely populated areas due to its high cost of installation and maintenance, and because the high reactive power produces large charging currents and difficulties in voltage management. Reactive power is an abstract quantity, typically used by power engineers to describe a certain type of energy flow in an electric distribution system. ...

A power transmission system is sometimes referred to colloquially as a "grid"; however, for reasons of economy, the network is not a mathematical grid. Redundant paths and lines are provided so that power can be routed from any power plant to any load center, through a variety of routes, based on the economics of the transmission path and the cost of power. Much analysis is done by transmission companies to determine the maximum reliable capacity of each line, which, due to system stability considerations, may be less than the physical or thermal limit of the line. Deregulation of electricity companies in many countries has led to renewed interest in reliable economic design of transmission networks. Example of regular grid. ... In engineering, the duplication of critical components of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe, is called redundancy. ... Deregulation is the process by which governments remove, reduce, or simplify restrictions on business and individuals in order to (in theory) encourage the efficient operation of markets. ...

AC power transmission

AC power transmission is the transmission of electric power by alternating current. Usually transmission lines use three phase AC current. In electric railways, single phase AC current is sometimes used in a railway electrification system. In urban areas, trains may be powered by DC at 600 volts or so. For delivered electrical power, see Electrical power industry. ... City lights viewed in a motion blurred exposure. ... Three-phase power transformer which is the sole transfer point for electricity to a suburban shopping mall in Canada. ... In electricity, current refers to electric current, which is the flow of electric charge. ... In electrical engineering, single-phase electric power refers to the distribution of electric power using a system in which all the voltages of the supply vary in unison. ... Overhead wire in Coventry, England Overhead wire and its suspension system in Bridgeport, Connecticut, USA A railway electrification system is a way of supplying electric power to electric locomotives and multiple units. ...

Overhead conductors are not covered by insulation. The conductor material is nearly always an aluminum alloy, made into several strands and possibly reinforced with steel strands. Conductors are a commodity supplied by several companies worldwide. Improvements in conductor material and shape may allow increased circuit capacity and is occasionally done to modernize and uprate a transmission circuit. Conductor sizes in overhead transmission work range in size from #6 American wire gauge (about 12 square millimetres) to 1,590,000 circular mils area (about 750 square millimetres), with varying resistance and current-carrying capacity. Thicker wires would lead to a relatively small increase in capacity due to the skin effect, that causes most of the current to flow close to the surface of the wire. American wire gauge (AWG), also known as the Brown and Sharpe wire gauge, is used in the United States and other countries as a standard method of denoting wire diameter, especially for nonferrous, electrically conducting wire. ... The skin effect is the tendency of an alternating electric current (AC) to distribute itself within a conductor so that the current density near the surface of the conductor is greater than that at its core. ...

Today, transmission-level voltages are usually considered to be 110 kV and above. Lower voltages such as 69 kV and 33 kV are usually considered sub-transmission voltages but are occasionally used on long lines with light loads. Voltages less than 33 kV are usually used for distribution. Voltages above 230 kV are considered extra high voltage and require different designs compared to equipment used at lower voltages. 11kV/400V-230V transformer in an older suburb of Wellington, New Zealand Electricity distribution is the penultimate stage in the delivery (before retail) of electricity to end users. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ...

Overhead transmission lines are uninsulated wire, so design of these lines requires minimum clearances to be observed to maintain safety.

History

In the early days of commercial use of electric power, transmission of electric power at the same voltage as used by lighting and mechanical loads restricted the distance between generating plant and consumers. Originally generation was with direct current, which could not easily be increased in voltage for long-distance transmission. Different classes of loads, for example, lighting, fixed motors, and traction (railway) systems, required different voltages and so used different generators and circuits. ^[1] Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...

At an AIEE meeting on May 16, 1888, Nikola Tesla delivered a lecture entitled A New System of Alternating Current Motors and Transformers, describing the equipment which allowed efficient generation and use of alternating currents. Tesla's disclosures, in the form of patents, lectures and technical articles, are useful for understanding the history of the modern system of power transmission. Ownership of the rights to the Tesla patents was a key commercial advantage to the Westinghouse Company in offering a complete alternating current power system for both lighting and power. The American Institute of Electrical Engineers was a United States based organization of electrical engineers that existed between 1884 and 1963 (when it merged with the Institute of Radio Engineers (IRE)). The 1884 founders of the American Institute of Electrical Engineers (AIEE) included some of the most prominent inventors and... May 16 is the 136th day of the year (137th in leap years) in the Gregorian calendar. ... For the toll-free telephone number see Toll-free telephone number Year 1888 (MDCCCLXXXVIII) was a leap year starting on Sunday (click on link for calendar) of the Gregorian calendar (or a leap year starting on Friday of the 12-day slower Julian calendar). ... Nikola Tesla (1856-1943)[1] was a world-renowned Serbian inventor, physicist, mechanical engineer and electrical engineer. ... City lights viewed in a motion blurred exposure. ... This article is about the defunct Westinghouse Electric Corporation founded in 1886, renamed CBS Corporation in 1997, and purchased by Viacom in 1999. ...

The so-called "universal system" used transformers both to couple generators to high-voltage transmission lines, and to connect transmission to local distribution circuits. By a suitable choice of utility frequency, both lighting and motor loads could be served. Rotary converters and later mercury-arc valves and other rectifier equipment allowed DC load to be served by local conversion where needed. Even generating stations and loads using different frequencies could also be interconnected using rotary converters. By using common generating plants for every type of load, important economies of scale were achieved, lower overall capital investment was required, load factor on each plant was increased allowing for higher efficiency, allowing for a lower cost of energy to the consumer and increased overall use of electric power. The waveform of 230 volt, 50 Hz compared with 110 V, 60 Hz. ... Rotary Converter refers to a class of electrical machinery that was used to convert one form of electrical power into another form. ... A mercury arc valve (mercury vapor rectifier) is a type of electrical rectifier which converts alternating current into direct current. ... ... Load Factor (LF) – The percentage of seats filled. ...

By allowing multiple generating plants to be interconnected over a wide area, electricity production cost was reduced. The most efficient available plants could be used to supply the varying loads during the day. Reliability was improved and capital investment cost was reduced, since stand-by generating capacity could be shared over many more customers and a wider geographic area. Remote and low-cost sources of energy, such as hydroelectric power or mine-mouth coal, could be exploited to lower energy production cost. ^[2] Hydroelectric dam diagram The waters of Llyn Stwlan, the upper reservoir of the Ffestiniog Pumped-Storage Scheme in north Wales, can just be glimpsed on the right. ...

The first transmission of three-phase alternating current using high voltage took place in 1891 during the international electricity exhibition in Frankfurt. A 25 kV transmission line, approximately 175 kilometers long, connected Lauffen on the Neckar and Frankfurt. Year 1891 (MDCCCXCI) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Saturday of the 12-day slower Julian calendar). ... For other uses, see Frankfurt (disambiguation). ... Lauffen is a town in the district of Heilbronn, Baden-Württemberg, Germany. ... The Neckar is a 367 km long river in Germany, a major right tributary of the River Rhine, which it joins at Mannheim. ...

Initially transmission lines were supported by porcelain pin-and-sleeve insulators similar to those used for telegraphs and telephone lines. However, these had a practical limit of 40 kV. In 1907, the invention of the disc insulator by Harold W. Buck of the Niagara Falls Power Corporation and Edward M. Hewlett of General Electric allowed practical insulators of any length to be constructed for higher voltages. The first large scale hydroelectric generators in the USA were installed at Niagara Falls and provided electricity to Buffalo, New York via power transmission lines. A statue of Tesla stands at Niagara Falls today in tribute to his contributions. This article or section is in need of attention from an expert on the subject. ... Telegraph and Telegram redirect here. ... For other uses, see Telephone (disambiguation). ... Year 1907 (MCMVII) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 13-day-slower Julian calendar). ... “GE” redirects here. ... For other uses, see Niagara Falls (disambiguation). ... Nickname: Location of Buffalo in New York State County Government  - Mayor Byron Brown (D) Area  - City 52. ...

Voltages used for electric power transmission increased throughout the 20th century. By 1914 fifty-five transmission systems operating at more than 70,000 V were in service, the highest voltage then used was 150,000 volts. ^[3] The first three-phase alternating current power transmission at 110 kV took place in 1912 between Lauchhammer and Riesa, Germany. On April 17, 1929 the first 220 kV line in Germany was completed, running from Brauweiler near Cologne, over Kelsterbach near Frankfurt, Rheinau near Mannheim, Ludwigsburg-Hoheneck near Austria. The masts of this line were designed for eventual upgrade to 380 kV. However the first transmission at 380 kV in Germany was on October 5, 1957 between the substations in Rommerskirchen and Ludwigsburg-Hoheneck. In 1967 the first extra-high-voltage transmission at 735 kV took place on a Hydro-Québec transmission line. In 1982 the first transmission at 1200 kV was in the Soviet Union. Lauchhammer is a town in the Oberspreewald-Lausitz district, in southern Brandenburg, Germany. ... Riesa - Wikipedia /**/ @import /skins/monobook/IE50Fixes. ... St. ... For other uses, see Cologne (disambiguation). ... Kelsterbach is a town in the district of Groß-Gerau, in Hesse, Germany. ... Rheinau may refer to: Rheinau, Switzerland, a town in the canton of Zürich Rheinau Abbey, in Rheinau, Switzerland Rheinau (Baden), a town in Baden-Württemberg, Germany a part of Mannheim, Germany This article consisting of geographical locations is a disambiguation page, a list of pages that otherwise might... Mannheim is a city in Germany. ... Ludwigsburg is a city in Germany, about 12 km north of Stuttgarts city center, near the river Neckar. ... This article needs to be wikified. ... Hydro-Québec is a crown corporation that provides hydroelectric power for Quebec, Canada and the north-eastern parts of the United States. ...

The rapid industrialization in the 20th century made electrical transmission lines and grids a critical part of the economic infrastructure in most industrialized nations. Interconnection of local generation plants and small distribution networks was greatly spurred by the requirements of World War I, where large electrical generating plants were built by governments to provide power to munitions factories; later these plants were connected to supply civil load through long-distance transmission. ^[4] (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999... “The Great War ” redirects here. ...

Small municipal electrical utilities did not necessarily desire to reduce the cost of each unit of electricity sold; to some extent, especially during the period 1880-1890, electrical lighting was considered a luxury product and electric power was not substituted for steam power. Engineers such as Samuel Insull in the United States and Sebastian Z. De Ferranti in the United Kingdom were instrumental in overcoming technical, economic, regulatory and political difficulties in development of long-distance electric power transmission. By introduction of electric power transmission networks, in the city of London the cost of a kilowatthour was reduced to one-third in a ten-year period. ^[5] Samuel Insull (November 11, 1859 - July 16, 1938) was an investor in Chicago who was known for purchasing utilities and railroads. ... Sebastian Ziani de Ferranti (1864-1930) was an electrical engineer and inventor. ...

In 1926 electrical networks in the United Kingdom began to be interconnected in the National Grid, initially operating at 132,000 volts. The National Grid is the high-voltage electric power transmission network in Great Britain, connecting power stations and major substations and ensuring that electricity generated anywhere in Great Britain can be used to satisfy demand elsewhere. ...

Bulk power transmission

Engineers design transmission networks to transport the energy as efficiently as feasible, while at the same time taking into account economic factors, network safety and redundancy. These networks use components such as power lines, cables, circuit breakers, switches and transformers. A 2 pole miniature circuit breaker A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. ... Figure 1:Three-phase pole-mounted step-down transformer. ...

A transmission substation decreases the voltage of electricity coming in allowing it to connect from long distance, high voltage transmission, to local, lower voltage, distribution. It also rerouts power to other transmission lines that serve local markets.

Transmission efficiency is improved by increasing the voltage using a step-up transformer, which reduces the current in the conductors, while keeping the power transmitted nearly equal to the power input. The reduced current flowing through the conductor reduces the losses in the conductor and since, according to Joule's Law, the losses are proportional to the square of the current, halving the current makes the transmission loss one quarter the original value. Image File history File linksMetadata Size of this preview: 800 × 600 pixelsFull resolution (1280 × 960 pixel, file size: 471 KB, MIME type: image/jpeg) A transmission substation on the electrical grid. ... Image File history File linksMetadata Size of this preview: 800 × 600 pixelsFull resolution (1280 × 960 pixel, file size: 471 KB, MIME type: image/jpeg) A transmission substation on the electrical grid. ... Figure 1:Three-phase pole-mounted step-down transformer. ... Joules law (also known as Joule effect) is a physical law expressing the relationship between the heat generated by the current flowing through a conductor. ...

A transmission grid is a network of power stations, transmission circuits, and substations. Energy is usually transmitted within the grid with three-phase AC. DC systems require relatively costly conversion equipment which may be economically justified for particular projects. Single phase AC is used only for distribution to end users since it is not usable for large polyphase induction motors. In the 19th century two-phase transmission was used, but required either three wires with unequal currents or four wires. Higher order phase systems require more than three wires, but deliver marginal benefits. A power station (also power plant) is a facility for the generation of electric power. ... Three phase systems have 3 waveforms (usually carrying power) that are 2/3π radians (120 degrees,1/3 of a cycle) offset in time. ... City lights viewed in a motion blurred exposure. ... HVDC or high-voltage, direct current electric power transmission systems contrast with the more common alternating-current systems as a means for the bulk transmission of electrical power. ... Induction Motor (IM) is one kind of AC motor where power is supplied to the rotating device by induction. ...

The capital cost of electric power stations is so high, and electric demand is so variable, that it is often cheaper to import some portion of the variable load than to generate it locally. Because nearby loads are often correlated (hot weather in the Southwest portion of the United States might cause many people there to turn on their air conditioners), imported electricity must often come from far away. Because of the economics of load balancing, transmission grids now span across countries and even large portions of continents. The web of interconnections between power producers and consumers ensures that power can flow even if a few links are inoperative.

The unvarying (or slowly varying over many hours) portion of the electric demand is known as the "base load", and is generally served best by large facilities (and therefore efficient due to economies of scale) with low variable costs for fuel and operations, i.e. nuclear, coal, and renewables like hydro, solar, wind, ocean, etc.. Smaller- and higher-cost sources are then added as needed. A base load power plant is one that provides a steady flow of power regardless of total power demand by the grid. ...

Long-distance transmission of electricity (thousands of miles) is cheap and efficient, with costs of US$ 0.005 to 0.02 per kilowatt-hour (compared to annual averaged large producer costs of US$ 0.01 to US$ 0.025 per kilowatt-hour, retail rates upwards of US$ 0.10 per kilowatt-hour, and multiples of retail for instantaneous suppliers at unpredicted highest demand moments).^[6] Thus distant suppliers can be cheaper than local sources (e.g. New York City buys a lot of electricity from Canada). Multiple local sources (even if more expensive and infrequently used) can make the transmission grid more fault tolerant to weather and other disasters that can disconnect distant suppliers.

Getting renewables connected into the long-distance transmission grid is critical for energy self-sufficiency. Hydro and wind sources can't be moved closer to high population cities, and solar costs are lowest in remote areas where local power needs are the least. Connection costs alone can determine whether any particular renewable alternative is economically sensible, e.g. costs can be prohibitive for redundant transmission lines up to distant mountain ridges where enormous quantities of economically valuable high speed winds blow reliably. Renewable energy (sources) or RES capture their energy from existing flows of energy, from on-going natural processes, such as sunshine, wind, flowing water, biological processes, and geothermal heat flows. ...

Grid input

At the generating plants the energy is produced at a relatively low voltage of up to 30 kV (Grigsby, 2001, p. 4-4), then stepped up by the power station transformer to a higher voltage (115 kV to 765 kV AC, ± 250-500 kV DC, varying by country) for transmission over long distances to grid exit points (substations). This article is about machines that produce electricity. ... Figure 1:Three-phase pole-mounted step-down transformer. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ...

Power lines near Birmingham, Alabama

Image File history File links Powerlinesky. ... Image File history File links Powerlinesky. ... Nickname: Location in Jefferson County in the state of Alabama Coordinates: , Country State County Jefferson, Shelby Government  - Mayor Bernard Kincaid (D) Area  - City  151. ...

Losses

Transmitting electricity at high voltage reduces the fraction of energy lost to Joule heating. For a given amount of power, a higher voltage reduces the current and thus the resistive losses in the conductor. Long distance transmission is typically done with overhead lines at voltages of 115 to 1,200 kV. However, at extremely high voltages, more than 2,000 kV between conductor and ground, corona discharge losses are so large that they can offset the lower resistance loss in the line conductors. In electronics, and in physics more broadly, Joule heating refers to the increase in temperature of a conductor as a result of resistance to an electrical current flowing through it. ... Joule heating is the process by which the passage of an electric current through a conductor releases heat. ... In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient exceeds a certain value, in situations where sparking (also known as arcing) is not favoured. ...

Transmission and distribution losses in the USA were estimated at 7.2% in 1995 [2], and in the UK at 7.4% in 1998. [3] Year 1995 (MCMXCV) was a common year starting on Sunday (link will display full 1995 Gregorian calendar). ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ...

As of 1980, the longest cost-effective distance for electricity was 4,000 miles (7,000 km), although all present transmission lines are considerably shorter. (see Present Limits of High-Voltage Transmission)

In an alternating current transmission line, the inductance and capacitance of the line conductors can be significant. The currents that flow in these components of transmission line impedance constitute reactive power, which transmits no energy to the load. Reactive current flow causes extra losses in the transmission circuit. The ratio of real power (transmitted to the load) to apparent power is the power factor. As reactive current increases, the reactive power increases and the power factor decreases. For systems with low power factors, losses are higher than for systems with high power factors. Utilities add capacitor banks and other components throughout the system — such as phase-shifting transformers, static VAR compensators, and flexible AC transmission systems (FACTS) — to control reactive power flow for reduction of losses and stabilization of system voltage. An electric current i flowing around a circuit produces a magnetic field and hence a magnetic flux Φ through the circuit. ... Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ... Electrical impedance, or simply impedance, is a measure of opposition to a sinusoidal alternating electric current. ... Reactive power is an abstract quantity, typically used by power engineers to describe a certain type of energy flow in an electric distribution system. ... The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power, and is a number between 0 and 1. ... Figure 1:Three-phase pole-mounted step-down transformer. ... Transmission lines both generate and absorb reactive power. ... Flexible Alternating Current Transmission System (FACTS) is a static equipment used for the AC transmission of electrical energy. ...

Electrical power is always partially lost by transmission. This applies to short distances such as between components on a printed circuit board as well as to cross country high voltage lines. The major component of power loss is due to ohmic losses in the conductors and is equal to the product of the resistance of the wire and the square of the current: For delivered electrical power, see Electrical power industry. ... Part of a 1983 Sinclair ZX Spectrum computer board. ... Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...

P_loss = RI²

For a system which delivers a power, P, at unity power factor at a particular voltage, V, the current flowing through the cables is given by . Thus, the power lost in the lines, . International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ...

Therefore, the power lost is proportional to the resistance and inversely proportional to the square of the voltage. A higher transmission voltage reduces the current and thus the power lost during transmission.

In addition, a low resistance is desirable in the cable. While copper cable could be used, aluminium alloy is preferred due to its much better conductivity to weight ratio making it lighter to support, as well as its lower cost. The aluminium is normally mechanically supported on a steel core. “Aluminum” redirects here. ...

HVDC

Main article: HVDC

High voltage direct current (HVDC) is used to transmit large amounts of power over long distances or for interconnections between asynchronous grids. When electrical energy is required to be transmitted over very long distances, it can be more economical to transmit using direct current instead of alternating current. For a long transmission line, the value of the smaller losses, and reduced construction cost of a DC line, can offset the additional cost of converter stations at each end of the line. Also, at high AC voltages significant (although economically acceptable) amounts of energy are lost due to corona discharge, the capacitance between phases or, in the case of buried cables, between phases and the soil or water in which the cable is buried. HVDC or high-voltage, direct current electric power transmission systems contrast with the more common alternating-current systems as a means for the bulk transmission of electrical power. ... Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ... City lights viewed in a motion blurred exposure. ... In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient exceeds a certain value, in situations where sparking (also known as arcing) is not favoured. ... Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland Technically, soil forms the pedosphere: the interface between the lithosphere (rocky part of the planet) and the biosphere, atmosphere, and hydrosphere. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ...

HVDC links are sometimes used to stabilize against control problems with the AC electricity flow. In other words, to transmit AC power as AC when needed in either direction between Seattle and Boston would require the (highly challenging) continuous real-time adjustment of the relative phase of the two electrical grids. With HVDC instead the interconnection would: (1) Convert AC in Seattle into HVDC. (2) Use HVDC for the three thousand miles of cross country transmission. Then (3) convert the HVDC to locally synchronized AC in Boston, and optionally in other cooperating cities along the transmission route. One prominent example of such a transmission line is the Pacific DC Intertie located in the Western United States. City nickname Emerald City City bird Great Blue Heron City flower Dahlia City mottos The City of Flowers The City of Goodwill City song Seattle, the Peerless City Mayor Greg Nickels County King County Area   - Total   - Land   - Water   - % water 369. ... Nickname: City on the Hill, Beantown, The Hub (of the Universe)1, Athens of America, The Cradle of Revolution, Puritan City, Americas Walking City Location in Massachusetts, USA Counties Suffolk County Mayor Thomas M. Menino(D) Area    - City 232. ... Look up Phase in Wiktionary, the free dictionary Phase may refer to: Phase (matter), a physically distinctive form of a substance, such as the solid, liquid, and gaseous states of ordinary matter Phase (waves), the time position (or angle in the complex plane) within a cycle of a periodic waveform... Map of the route of the Pacific Intertie transmission route and stations The Pacific DC Intertie (also called Path 65) is an electric power transmission line which transmits electricity from the Pacific Northwest to the Los Angeles area using high voltage direct current (HVDC). ...

Grid exit

At the substations, transformers are again used to step the voltage down to a lower voltage for distribution to commercial and residential users. This distribution is accomplished with a combination of sub-transmission (33 kV to 115 kV, varying by country and customer requirements) and distribution (3.3 to 25 kV). Finally, at the point of use, the energy is transformed to low voltage (100 to 600 V, varying by country and customer requirements). A 115 kV to 41. ... 11kV/400V-230V transformer in an older suburb of Wellington, New Zealand Electricity distribution is the penultimate stage in the delivery (before retail) of electricity to end users. ...

Communications

Operators of long transmission lines require reliable communications for control of the power grid and, often, associated generation and distribution facilities. Fault-sensing protection relays at each end of the line must communicate to monitor the flow of power into and out of the protected line section so that faulted conductors or equipment can be quickly de-energized and the balance of the system restored. Protection of the transmission line from short circuits and other faults is usually so critical that common carrier telecommunications are insufficiently reliable. In remote areas a common carrier may not be available at all. Communication systems associated with a transmission project may use: SCADA is the acronym for Supervisory Control And Data Acquisition. ... Automotive style miniature relay A relay is an electrical switch that opens and closes under the control of another electrical circuit. ... For alternate meanings see Short circuit (disambiguation) A short circuit (sometimes known as simply a short) is a fault whereby electricity moves through a circuit in an unintended path, usually due to a connection forming where none was expected. ... A common carrier is an organization that transports persons or goods, and offers its services to the general public. ...

• Microwaves
• Power line communication
• Optical fibres

Rarely, and for short distances, a utility will use pilot-wires strung along the transmission line path. Leased circuits from common carriers are not preferred since availability is not under control of the electric power transmission organization. This article is about the type of Electromagnetic radiation. ... For other uses, see Power band. ... Fiber Optic strands An optical fiber in American English or fibre in British English is a transparent thin fiber for transmitting light. ...

Transmission lines can also be used to carry data: this is called power-line carrier, or PLC. PLC signals can be easily received with a radio for the long wave range. For other uses, see Power band. ...

Optical fibres can be included in the stranded conductors of a transmission line, in the overhead shield wires. These cables are known as OPGW or Optical Ground Wire. Sometimes a standalone cable is used, ADSS or All Dielectric Self Supporting cable, attached to the transmission line cross arms. Optical fiber composite overhead ground wire (OPGW) is a type of cable that is used in the construction of electric power transmission and distribution lines. ...

110 kV double circuit power line of EnBW AG near Leonberg, Germany with an aerial cable mounted like a garland on the ground conductor

Some jurisdictions, such as Minnesota, prohibit energy transmission companies from selling surplus communication bandwidth or acting as a telecommunications common carrier. Where the regulatory structure permits, the utility can sell capacity in extra "dark fibres" to a common carrier, providing another revenue stream for the line. Image File history File links Download high-resolution version (1536x864, 124 KB)110kV-powerline of EnBW AG with aerial cable mounted like a garland on the ground conductor near Leonberg in Germany Source: http://upload. ... Image File history File links Download high-resolution version (1536x864, 124 KB)110kV-powerline of EnBW AG with aerial cable mounted like a garland on the ground conductor near Leonberg in Germany Source: http://upload. ... Capital Saint Paul Largest city Minneapolis Area  Ranked 12th  - Total 87,014 sq mi (225,365 km²)  - Width 250 miles (400 km)  - Length 400 miles (645 km)  - % water 8. ... A common carrier is an organization that transports persons or goods, and offers its services to the general public. ...

Electricity market reform

Transmission towers in the New Zealand countryside

Transmission is a natural monopoly and there are moves in many countries to separately regulate transmission (see Electricity market). Transmission towers marching through the countryside. ... Transmission towers marching through the countryside. ... “Pylon” redirects here. ... In economics, the term natural monopoly is used to refer to two different things. ... An electricity market is a system for effecting the purchase and sale of electricity using supply and demand to set the price. ...

Spain was the first country to establish a Regional Transmission Organization. In that country transmission operations and market operations are controlled by separate companies. The transmission system operator is Red Eléctrica de España (REE) [4] and the wholesale electricity market operator is Operador del Mercado Ibérico de Energía - Polo Español, S.A. (OMEL) [5]. Spain's transmission system is interconnected with those of France, Portugal, and Morocco.

In the United States and parts of Canada, electrical transmission companies operate independently of generation and distribution companies.

Merchant transmission

Merchant transmission is an arrangement where a third party constructs and operates electric transmission lines through the franchise area of an unrelated utility. Advocates of merchant transmission^{[attribution needed]} claim that this will create competition to construct the most efficient and lowest cost additions to the transmission grid. Merchant transmission projects typically involve DC lines because it is easier to limit flows to paying customers.

The only operating merchant transmission project in the United States is the Cross Sound Cable from Long Island, New York to New Haven, Connecticut, although additional projects have been proposed. The Cross Sound Cable is a 40 kilometer (about 25 miles) long bipolar High-voltage direct current (HVDC) submarine power cable between New Haven, Connecticut, USA and Shoreham, Long Island New York , USA. The Cross Sound Cable can transmit a maximum power of 330 MW at a voltage of 150... This article is about Long Island in New York State. ... “New Haven” redirects here. ...

There are five merchant transmission interconnectors between five states in Australia: the DirectLink, QNI, MurrayLink and Southern Link between New South Wales and South Australia and Basslink between Tasmania and Victoria. The Basslink is a HVDC link between the static inverter plant Loy Yang on the Australian mainland and the static inverter plant George Town in Northern Tasmania. ...

A major barrier to wider adoption of merchant transmission is the difficulty in identifying who benefits from the facility so that the beneficiaries will pay the toll. Also, it is difficult for a merchant transmission line to compete when the alternative transmission lines are subsidized by other utility businesses.^[7]

Health concerns

Main article: Electromagnetic radiation and health

Some research has found that exposure to elevated levels of ELF magnetic fields such as those originating from electric power transmission lines may be implicated in a number of adverse health effects. These include, but are not limited to, childhood Leukemia ^[8], adult leukemia^[9], breast cancer^[10], neurodegenerative diseases (such as amyotrophic lateral sclerosis)^[11][12][13], Miscarriage^[14][15][16], and clinical depression. Although there seems to be a small statistical correlation between various diseases and living near power lines, the physical mechanism is not clear. One proposed mechanism is that the electric fields around power lines attract aerosol pollutants.^[17][18] Electromagnetic radiation can be classified into ionizing radiation and non-ionizing radiation, based on whether it is capable of ionizing atoms and breaking chemical bonds. ... Acute lymphoblastic leukemia (ALL), also known as acute lymphocytic leukemia, is a cancer of the white blood cells, characterised by the overproduction and continuous multiplication of malignant and immature white blood cells (referred to as lymphoblasts) in the bone marrow. ... Breast cancer is cancer of breast tissue. ... Amyotrophic lateral sclerosis (ALS, sometimes called Lou Gehrigs Disease, Maladie de Charcot or motor neurone disease) is a progressive, fatal, neurodegenerative disease caused by the degeneration of motor neurons, the nerve cells in the central nervous system that control voluntary muscle movement. ... Miscarriage or spontaneous abortion is the natural or spontaneous end of a pregnancy at a stage where the embryo or the fetus is incapable of surviving, generally defined in humans at a gestation of prior to 20 weeks. ... Clinical depression (also called major depressive disorder, or unipolar depression when compared to bipolar disorder) is a state of intense sadness, melancholia or despair that has advanced to the point of being disruptive to an individuals social functioning and/or activities of daily living. ... Aerosol, is a term derived from the fact that matter floating in air is a suspension (a mixture in which solid or liquid or combined solid-liquid particles are suspended in a fluid). ...

One possible response to the potential dangers of overhead power lines is to place them underground. According to the British Stakeholder Advisory Group on ELF EMFs^[19], the cost of burying cables at transmission voltages costs is around GBP 10M/km, compared to GBP 0.5-1M/km for overhead lines.

Underground cables eliminate the electric field and reduce the width over which the magnetic field is elevated.^[20] However, in reality, protection from the dangers of electromagnetic (EM) fields is seldom the driving concern when burying power lines.

The strongest evidence linking EMF to cancer was fabricated. Most people, when quizzed, have heard of the link between EMF's and cancer, but relatively few people have heard of the fabricated data leaving a public perception that power lines are far more dangerous than they are.

http://www.sciencemag.org/cgi/content/summary/285/5424/23b

Special transmission grids for railways

In some countries where electric trains run on low frequency AC (e.g. 16.7 Hz and 25 Hz) power there are separate single phase traction power networks operated by the railways. These grids are fed by separate generators in some traction powerstations or by traction current converter plants from the public three phase AC network. A GG1, perhaps the best-known electric locomotive ever built. ... A traction power network is an electricity grid for the supply of electric trains. ... A traction powerstation is a power station, which produces only traction current. ... A traction current converter plant is an electrical substation that converts electric power from that form used as public electricity mains current to an appropriate voltage, current type, and frequency to supply railways with traction current. ...

Superconducting cables

High-temperature superconductors promise to revolutionize power distribution by providing lossless transmission of electrical power. The development of superconductors with transition temperatures higher than the boiling boint of liquid nitrogen has made the concept of superconducting power lines commercially feasible, at least for high-load applications. ^[21] It has been estimated that the waste would be halved using this method, since the necessary refrigeration equipment would consume about half the power saved by the elimination of the majority of resistive losses. Such cables are particularly suited to high load density areas such as the business district of large cities, where purchase of a wayleave for cables would be very costly. [6] Unsolved problems in physics: Why do certain materials exhibit superconductivity at temperatures much higher than 50 kelvins? The term high-temperature superconductor was initially employed to designate the new family of cuprate-perovskite ceramic materials discovered by J.G. Bednorz and K.A. Müller in 1986. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... An easement is the right to do something or the right to prevent something over the real property of another. ...

Wireless power transmission

Main article: wireless power transmission

Every radio transmitter emits power wirelessly. For example, the operation of a crystal radio is powered by the radio station it is tuned to, however the energetic efficiency is extremely low. Wireless energy transfer is wireless transfer of electromagnetic energy via electromagnetic induction. ... Antenna tower of Crystal Palace transmitter, London A transmitter (sometimes abbreviated XMTR) is an electronic device which with the aid of an antenna propagates an electromagnetic signal such as radio, television, or other telecommunications. ... An example of a modern set created by VE6AB The crystal radio receiver (also known as a crystal set) is a very simple kind of radio receiver. ...

Small scale wireless power was demonstrated as early as 1831 by Michael Faraday and by 1888 Heinrich Rudolf Hertz had proven that natural radio waves exist and can be captured. Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed significantly to the fields of electromagnetism and electrochemistry. ... Heinrich Rudolf Hertz (February 22, 1857 - January 1, 1894) was the German physicist and mechanician for whom the hertz, an SI unit, is named. ...

Both Nikola Tesla and Hidetsugu Yagi attempted to devise systems for large scale wireless power transmission. Tesla succeeded,^{[22][23][24][25][26]} but his investors saw no way they could profit from it because the consumption could not be controlled for billing and so not only refused to fund construction of larger transmitters but had the existing ones dismantled. Yagi also proposed a similar concept, but the engineering problems proved to be more onerous than conventional systems. His work, however, led to the invention of the Yagi antenna. Nikola Tesla (1856-1943)[1] was a world-renowned Serbian inventor, physicist, mechanical engineer and electrical engineer. ... Hidetsugu Yagi (八木 秀次 Yagi Hidetsugu, January 28, 1886 - January 19, 1976) was a Japanese electrical scientist who wrote several important articles that led to the development of the Yagi antenna, which allows directional communication with electromagnetic waves. ... A Yagi-Uda antenna. ...

Another form of wireless power transmission has been studied for transmission of power from solar power satellites to the earth. A high power array of microwave transmitters would beam power to a rectenna. Major engineering and economic challenges face any solar power satellite project. An artists depiction of a solar satellite, which could send energy wirelessly to a space vessel or planetary surface. ... This article is about the type of Electromagnetic radiation. ... A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity. ...

Records

• Highest transmission voltage (AC): 1,150 kV on Powerline Ekibastuz-Kokshetau (Kazakhstan)
• Highest transmission voltage (DC): +/-600 kV on HVDC Itaipu (Brazil)
• Highest pylons: Yangtze River Crossing (height: 345 m (1,132 ft))
• Longest powerline: Inga-Shaba (length: 1,700 km (1,056 mi))
• Longest span of powerline: 5,376 m (17,638 ft) at Ameralik Span
• Longest submarine cables:
  • Basslink, Bass Strait - (length of submarine/underground cable: 290 km (180 mi), total length: 357.4 km (222 mi))
  • Baltic-Cable, Baltic Sea - (length of submarine/underground cable: 249 km (155 mi), total length: 261 km (162 mi))

The Powerline Ekibastuz-Kokshetau is the powerline designed for the highest transmission voltage (1150 kV) in the world. ... The HVDC Itaipu is a HVDC transmission line from the Itaipu hydroelectric power plant to the city of São Roque - SP, Brazil. ... “Pylon” redirects here. ... The Yangtze River Crossing may refer to one of three overhead power lines crossing the Yangtze River, China. ... The Inga-Shaba EHVDC Transmission Line is an electric cable in the Democratic Republic of Congo. ... Ameralik Span is the worlds longest span of an overhead powerline in the world. ... The Basslink is a HVDC link between the static inverter plant Loy Yang on the Australian mainland and the static inverter plant George Town in Northern Tasmania. ... Map of Australia with Bass Strait marked in light blue Bass Strait (IPA: ) is a sea strait separating Tasmania from the south of the Australian mainland (Victoria in particular). ... The Baltic Cable is a HVDC power line running beneath the Baltic Sea that interconnects the electric power grids of Germany and Sweden. ... The Baltic Sea is located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. ...

See also

Dynamic Demand the name of a semi-passive technology for adjusting load demands on an electrical power grid. ... Explanation of demand response effects on a quantity (Q) - price (P) graph. ... Distributed generation generates electricity from many small energy sources. ... 11kV/400V-230V transformer in an older suburb of Wellington, New Zealand Electricity distribution is the penultimate stage in the delivery (before retail) of electricity to end users. ... An electricity market is a system for effecting the purchase and sale of electricity using supply and demand to set the price. ... “Pylon” redirects here. ... Flexible Alternating Current Transmission System (FACTS) is a static equipment used for the AC transmission of electrical energy. ... A Grid-tied electrical system, also called Tied to grid or Grid tie system, is a semi autonomous electrical generation system which links to the mains to feed excess generation capacity back to the local mains electrical grid. ... HVDC or high-voltage, direct current electric power transmission systems contrast with the more common alternating current systems as a means for the bulk transmission of electrical power. ... In electronics, a load profile is a graph of the changes in the electrical load on an electrical device versus time. ... The term off the grid refers to a method of construction that relies on renewable energy sources rather than traditional public utility sources provided by the utility grid. ... This article or section is in need of attention from an expert on the subject. ... For other uses, see Power band. ... Power Outage is an episode of The WB drama series, Charmed. ... A submarine communications cable is a cable laid beneath the sea to carry telecommunications between countries. ... By traction current one understands the electric current, which is used for the drive of electrical trains. ... A traction power network is an electricity grid for the supply of electric trains. ... Three-phase power transformer which is the sole transfer point for electricity to a suburban shopping mall in Canada. ... Vehicle to Grid (V2G) technology is a bi-directional grid interface for gridable Electric vehicles such as Battery Electric Vehicles (BEV) and Plug-in Hybrid Electric Vehicles (PHEV). ... In electric power transmission, wheeling is a term used to describe the transportation of electric power over transmission lines. ... It has been suggested that Power beaming be merged into this article or section. ...

Notes

Thomas Parke Hughes is Mellon Professor of the History and Sociology of Science, Emeritus, at the University of Pennsylvania, and Visiting Professor at MIT and Stanford University. ...

Further reading

• Grigsby, L. L., et al. The Electric Power Engineering Handbook. USA: CRC Press. (2001). ISBN 0-8493-8578-4
• Thomas P. Hughes, Networks of Power: Electrification in Western Society 1880-1930, The Johns Hopkins University Press,Baltimore 1983 ISBN 0-8018-2873-2, an excellent overview of development during the first 50 years of commercial electric power

• Westinghouse Electric Corporation, "Electric power transmission patents; Tesla polyphase system". (Transmission of power; polyphase system; Tesla patents)

Thomas Parke Hughes is Mellon Professor of the History and Sociology of Science, Emeritus, at the University of Pennsylvania, and Visiting Professor at MIT and Stanford University. ... Below is a list of Tesla patents. ...

External links

• Japan: World's First In-Grid High-Temperature Superconducting Power Cable System
• A Power Grid for the Hydrogen Economy: Overview/A Continental SuperGrid
• Global Energy Network Institute (GENI) - The GENI Initiative focuses on linking renewable energy resources around the world using international electricity transmission.
• Union for the Co-ordination of Transmission of Electricity (UCTE), the association of transmission system operators in continental Europe, running one of the two largest power transmission systems in the world
• Non-Ionizing Radiation, Part 1: Static and Extremely Low-Frequency (ELF) Electric and Magnetic Fields (2002) by the IARC -- Link Broken.
• Trustworthy Cyber Infrastructure for the Power Grid (TCIP) - The TCIP group at the University of Illinois at Urbana-Champaign has developed applets to illustrate important concepts in mathematics and the science of electricity and the power grid.