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A table lamp connected to wall-plug (mains) power.
A table lamp connected to wall-plug (mains) power.

Mains is the general purpose alternating current (AC) electrical power supply (as in "I've connected the appliance to the mains"). An alternating current ( AC) is an Electric current whose direction reverses cyclically as opposed to Direct current, whose direction remains constant Electric power is defined as the rate at which Electrical energy is transferred by an Electric circuit. The term is not often used in the United States and Canada. The United States of America —commonly referred to as the Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page In the US, mains power has a variety of names. These include household power, household electricity, domestic power, wall power, line power, AC power, city power, and grid power. In Canada, it is sometimes called hydro, because much of the Canadian electrical generating capacity is hydroelectric. Hydroelectricity is electricity generated by Hydropower, ie the production of power through use of the gravitational force of falling water

Contents

Mains power systems

Main article: mains power systems

Worldwide, many different mains power systems are found for the operation of household and light commercial electrical appliances and lighting. This article includes a list of countries and territories with the plugs voltages and frequencies they use for providing electrical power to Small appliances This article includes a list of countries and territories with the plugs voltages and frequencies they use for providing electrical power to Small appliances The different systems are primarily characterized by their

but also by their

All these parameters vary among regions. "Electrocute" redirects here For the band see Electrocute (band. The voltages are generally in the range 100–240 V (always expressed as root-mean-square voltage). The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force. In Mathematics, the root mean square (abbreviated RMS or rms) also known as the quadratic mean, is a statistical measure of the The two commonly used frequencies are 50 Hz and 60 Hz. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second.

Some territories use standards different from those of the countries they belong to (such as Hong Kong in China). Hong Kong ( officially the Hong Kong Special Administrative Region, is a territory located on China 's south coast on the Pearl River Delta, and borders Talk People's Republic of China) PEOPLE'S REPUBLIC OF CHINA ARTICLE GUIDELINES Foreign enclaves, such as large industrial plants or overseas military bases, may have a different standard voltage and frequency from the surrounding areas. Some city areas may use standards different from that of the surrounding countryside. Regions in an effective state of anarchy may have no central electrical authority, with electric power provided by incompatible private sources. Anarchy (from αναρχία anarchía, "without ruler " may refer to any of the following "Absence of government a state of lawlessness

Many other combinations of voltage and utility frequency, including direct current, were formerly used, with frequencies between 25 Hz and 133 Hz and voltages from 100 to 250 V. The utility frequency ( American English) or mains frequency ( British English) is the Frequency at which Alternating current (AC is The modern standard combinations of 230 V/50 Hz and 120 V/60 Hz did not apply in the first few decades of the 20th century and are still not universal. International Standard IEC 60038 defines a set of standard voltages for use in Low voltage and High voltage AC Electricity supply

Industrial plants with polyphase power systems will have different, higher, voltages installed for large equipment (and different sockets and plugs), but the common voltages listed here would still be found for lighting and portable equipment. A polyphase system is a means of distributing Alternating current electrical power.

Building wiring

In most countries, household power is single-phase electric power, with two or three wired contacts at each outlet. In electrical engineering single-phase electric power refers to the distribution of Alternating current Electric power using a system in which all the voltages of

For more details on this topic, see Ground and neutral. Since the neutral point of an electrical supply system is often connected to earth ground ground and neutral are closely related

Various earthing systems are used to ensure that the ground and neutral wires have the correct voltages, to prevent shocks when touching grounded objects. In Sulvent systems an earthing system defines the Electrical potential of the conductors relative to that of the Earth's conductive surface

In some installations, there may be two live conductors which carry alternating currents in a rthree wire single-phase circuit. An alternating current ( AC) is an Electric current whose direction reverses cyclically as opposed to Direct current, whose direction remains constant A split phase Electricity distribution system is a 3-wire Single-phase distribution system commonly used in North America for single-family residential and light

Small portable electrical equipment is connected to the power supply through flexible cables terminated in a plug, which is then inserted into a fixed receptacle (socket). Larger household electrical equipment and industrial equipment may be permanently wired to the fixed wiring of the building. For example, in North American homes a window-mounted self-contained air conditioner unit would be connected to a wall plug, whereas the central air conditioning for a whole home would be permanently wired. An air conditioner is an Appliance, System, or mechanism designed to extract Heat from an area via a Refrigeration cycle Larger plug and socket combinations are used for industrial equipment carrying larger currents, higher voltages, or three phase electric power. Industrial and multiphase plugs and sockets provide a connection to the electrical mains rated at higher voltages and currents than household plugs and sockets This article deals with where how and why "three phase" is used

Circuit breakers and fuses are used to detect short circuits between the live and neutral wires, or the drawing of more current than the wires are rated to handle to prevent overheating and fire. A circuit breaker is an automatically-operated electrical Switch designed to protect an electrical circuit from damage caused by overload or In Electronics and Electrical engineering a fuse (short for fusible link) is a type of Overcurrent protection device Short Circuit is a 1986 comedy Science fiction film starring Ally Sheedy and Steve Guttenberg and directed by These protective devices are usually mounted in a central panel in a building, but some wiring systems also provide an over current protection device at the socket or within the plug.

Residual-current devices, also known as ground-fault current interrupt devices and appliance leakage current interrupters, are used to detect ground faults - leakage of current to someplace other than the neutral and live wires (like the ground wire or a person). A residual current device ( RCD) is similar to that of a residual current circuit breaker ( RCCB) is an Electrical wiring device that disconnects When a ground fault is detected, the device quickly cuts off the circuit.

Voltage levels

All European and most African and Asian countries use a supply that is within 10% of 230 V, whereas Japan, North America and some parts of South America use a voltage between 100 and 127 V. The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force. For a topic outline on this subject see List of basic Japan topics. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a

A distinction should be made between the voltage at the point of supply (nominal system voltage) and the voltage rating of the equipment (utilization voltage). Typically the utilization voltage is 3% to 5% lower than the nominal system voltage; for example, a nominal 208 V supply system will be connected to motors with "200 V" on their nameplates. This allows for the voltage drop between equipment and supply. Voltage drop is the reduction in Voltage in an Electrical circuit between the source and load Voltages in this article are the nominal supply voltages and equipment used on these systems will carry slightly lower nameplate voltages.

Voltage tolerances are for steady-state operation. Momentary heavy loads, or switching operations in the power distribution network, may cause short-term deviations out of the tolerance band. In general, power supplies derived from large networks with many sources will be more stable than those supplied to an isolated community with perhaps only a single generator.

The choice of utilization voltage is governed more by tradition than by optimization of the distribution system. In theory a 230 V distribution system will use less conductor material to deliver a given quantity of power. Incandescent lamps for 120 V systems are more efficient and rugged than 230 V lamps, while large heating appliances can use smaller conductors at 230 V for the same output rating. The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general Practically speaking, few household appliances use anything like the full capacity of the outlet to which they are connected. Minimum wire sizes for hand-held or portable equipment is usually restricted by the mechanical strength of the conductors. One may observe that both 230 V system countries and 120 V system countries have extensive penetration of electrical appliances in homes. National electrical codes prescribe wiring methods intended to minimize the risk of electric shock or fire. Electrical wiring in general refers to insulated conductors used to carry Electricity, and associated devices

Many areas using (nominally) 120 V make use of three-wire, single-phase 240 V systems to supply large appliances. A split phase Electricity distribution system is a 3-wire Single-phase distribution system commonly used in North America for single-family residential and light Three-phase systems can be connected to give various combinations of voltage, suitable for use by different classes of equipment. This article deals with the basic mathematics and principles of three-phase electricity North American three-phase voltage configurations common in commercial and industrial buildings are 120/208V, 277/480V and 347/600V all at 60Hz. Most larger commercial and industrial equipment and lighting runs at these higher voltages rather than 120V or 240V. Other voltages, up to 830 Volts, are occasionally used for special purpose systems such as oil well pumps.

Following voltage harmonization all electricity supply within the European Union is now nominally 230 V ± 10% at 50 Hz [1]. The European Union ( EU) is a political and economic union of twenty-seven member states, located primarily in The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. For a transition period (1995–2008), countries who previously used 220 V will use a narrower asymmetric tolerance range of 230 V +6% −10% and those (like the UK) who previously used 240 V use now 230 V +10% −6%[2]. Note that no change in voltage is required by either system as both 220V and 240V fall within the lower 230 V tolerance bands (230 V ±6%). In practice this means that countries such as the UK that previously supplied 240 V continue to do so, and those that previously supplied 220 V continue to do so. However equipment should be designed to accept any voltages within the specified range.

In the United States[3] and Canada[4], national standards specify that the nominal voltage at the source should be 120 V and allow a range of 114 to 126 V (-5% to +5%). Historically 110, 115 and 117 volts have been used at different times and places in North America. Main power is sometimes spoken of as “one-ten”; however, 120 is the nominal voltage.

As of the year 2000, Australia has converted to 230 V as the nominal standard with a tolerance of +10% -6%. For a topic outline on this subject see List of basic Australia topics. [5], this superseding the old 240 V standard, AS2926-1987. [6] As in the UK, 240 V is within the allowable limits and “240 volt” spoken as “two forty volt” remains a synonym for mains in Australian and British English. Australian English ( AuE, AusE, en-AU) is the form of the English language used in Australia. British English or UK English ( BrE, BE, en-GB) is the broad term used to distinguish the forms of the English language used in the

In Japan, the electrical power supply to households is at 100 V. For a topic outline on this subject see List of basic Japan topics. Eastern and northern parts of Honshū (including Tokyo) and Hokkaidō have a frequency of 50 Hz, whereas western Honshu (including Nagoya, Osaka, and Hiroshima), Shikoku, Kyūshū and Okinawa operate at 60 Hz. or Honshu is the largest Island of Japan. The nation's main island, it is south of Hokkaidō across the Tsugaru Strait, north of officially, is one of the 47 prefectures of Japan and located on the eastern side of the main island Honshū. WikipediaWikiProject Japanese prefectures for guidelines --> formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan 's The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. is the smallest (225 km long and between 50 and 150 km wide and least populous (4141955 as of 2005 of the four main islands of Japan, located south of Honshū or Kyushu is the third-largest Island of Japan and most southwesterly of its four main islands. is one of Japan 's southern prefectures, and consists of hundreds of the Ryukyu Islands in a chain over 1000 km long which extends southwest from Kyūshū To accommodate the difference, appliances marketed in Japan can often be switched between the two frequencies.

In all countries, large industrial motors (usually >250HP) may operate on Medium Voltage. On 60Hz systems a standard for medium voltage equipment is 2300/4160V whereas 3300V is the common standard for 50Hz systems.

History of voltage and frequency

Voltage & frequency around the world
Voltage & frequency around the world
A 50 Hz ±5 Hz vibrating-reed mains frequency meter for 220 V(this device was made in Czechoslovakia in 1967)
A 50 Hz ±5 Hz vibrating-reed mains frequency meter for 220 V
(this device was made in Czechoslovakia in 1967)

The system of three-phase alternating current electrical generation and distribution was invented by several persons in the 19th Century including Nikola Tesla, George Westinghouse and others. Czechoslovakia may also refer to what is now the Czech Republic and Slovakia. This article deals with the basic mathematics and principles of three-phase electricity There have already been discussions about Tesla's ethnicity on the talk page George Westinghouse Jr ( 6 October 1846 &ndash 12 March 1914) was an American Entrepreneur and Engineer Thomas Edison developed direct current (DC) systems at 110 V and this was claimed to be safer. Direct current ( DC) is the unidirectional flow of Electric charge. For more information about the early battles between proponents of AC and DC supply systems see War of Currents. In the "War of Currents" era (sometimes "War of the Currents" or "Battle of Currents") in the late 1880s George Westinghouse The 110 volt level was chosen to make high-resistance carbon filament lamps practical and economically competitive with gas lighting. Gas lighting refers to a technology used to produce light from gas usually methane but also including hydrogen and ethylene While higher voltages would reduce the current required for a given quantity of lamps, the filaments would become increasingly fragile and short-lived; Edison selected 100 volts as a compromise between distribution costs and lamp costs. generation was at 110 volts to allow for a voltage drop between generator and lamp. Voltage drop is the reduction in Voltage in an Electrical circuit between the source and load

In the 1880s only carbon-filament incandescent lamps were available, designed for a voltage of around 100 volts. Later metal filament lamps became feasible. In 1899, the Berliner Elektrizitäts-Werk (BEW), a Berlin electrical utility, decided to greatly increase its distribution capacity by switching to 220 volt nominal distribution, taking advantage of the higher voltage capability of metal filament lamps. Berlin is the capital city and one of sixteen states of Germany. The company was able to offset the cost of converting the customer's equipment by the resulting saving in distribution conductors cost. This became the model for electrical distribution in Germany and the rest of Europe and the 220-volt (later 230-volt) system became common. North American practice remained with voltages near 110 volts for lamps. [7]

In 1883 Edison patented a three wire distribution system to allow DC generation plants to serve a wider radius of customers. A split phase Electricity distribution system is a 3-wire Single-phase distribution system commonly used in North America for single-family residential and light This saved on copper costs since lamps were connected in series on a 220 volt system, with a neutral conductor connected between to carry any unbalance between the two sub-circuits. This was later adapted to AC circuits. Most lighting and small appliances ran on 120 V, while big appliances could be connected to 240 V. This system saved copper and was backward-compatible with existing appliances. Also, the original plugs could be used with the revised system.

Many different power frequencies were used in the 19th century. The utility frequency ( American English) or mains frequency ( British English) is the Frequency at which Alternating current (AC is As the 20th century continued, more power was produced at 60 Hz (North America) or 50 Hz (Europe and most of Asia). Standardization allowed international trade in electrical equipment; much later, the use of standard frequencies allowed international connections of power grids. The first units at the Niagara Falls generating station produced 25 Hz power and some early systems used 25 Hz. A few industrial customers still use 25 Hz power in the Niagara Region of Ontario and Western New York, from the hydro-electric plants on the Niagara River or from frequency changers operated off the 60 Hz network. Ontario (ɒnˈtɛrioʊ is a province located in the central part of Canada, the largest by population and second largest after Quebec Western New York refers to the westernmost region of New York State. The Niagara River flows to the north from Lake Erie to Lake Ontario. A frequency changer or frequency converter is an electronic device that converts Alternating current ( AC) of one Frequency to Residential and commercial customers in Canada were converted to 60 Hz equipment starting in 1949.

The German company AEG (descended from a company founded by Edison in Germany) built the first European generating facility to run at 50 Hz, allegedly because 60 was not a preferred number. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. AEG ( Allgemeine Elektrizitäts-Gesellschaft, General Electricity Company) was a German producer of Electronics and electrical equipment In Industrial design, product developers must choose numerous lengths distances diameters volumes and other characteristic quantities. At that time, AEG had a virtual monopoly and their standard spread to the rest of the continent. In Economics, a monopoly (from Greek monos, alone or single + polein, to sell exists when a specific individual or enterprise has sufficient In Britain, differing frequencies (including 25 Hz, 40 Hz, and DC) proliferated. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Implementation of the National Grid in the United Kingdom starting in 1926 compelled the standardization of frequencies among the many interconnected electrical service providers. The National Grid is the high-voltage Electric power transmission network in Great Britain, connecting Power stations and major substations and Notably, the large NESCO network in the north-east part of England was converted at great expense from 40 Hz to 50 Hz to match the national grid. The Newcastle-upon-Tyne Electric Supply Company was founded in Newcastle upon Tyne, UK, in 1889 by the industrialist John Theodore Merz (1840-1922 [8] The 50 Hz standard was completely established only after World War II. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Similarly, parts of California used 50 Hz power and did not convert to 60 Hz until the late 1940s. California ( is a US state on the West Coast of the United States, along the Pacific Ocean.

Frequency stability

In AC distribution networks, frequency variations control the transfer of energy between different parts of the network, and help the operators of generators to match demand and supply. If additional loads are connected somewhere in a network, nearby generators will supply larger currents, which slows down their rotational speed due to Lenz's law. Lenz's law (ˈlɛntsɨz ˌlɔː gives the direction of the induced Electromotive force (emf and current resulting from Electromagnetic induction. This reduces their output frequency and their network vicinity will fall behind in phase compared to other parts of the network. The phase of an oscillation or wave is the fraction of a complete cycle corresponding to an offset in the displacement from a specified reference point at time t = 0 This phase difference in turn increases currents flowing in from generators further away. After a short time, all generators in the network will have settled at a new, lower frequency. Control systems in power plants then detect this drop in the network-wide frequency and open steam valves in turbines to accelerate the generators back to their target frequency. This counteracting usually takes a few tens of seconds due to the large rotating masses involved. Temporary frequency changes are an unavoidable consequence of changing demand. Exceptional or rapidly changing mains frequency is often a sign that an electricity distribution network is operating near its capacity limits, dramatic examples of which can sometimes be observed shortly before major outages.

Long-term stability and clock synchronization

Frequency stabilization of large interconnected power systems allow line-operated clocks to keep accurate time. Network operators will regulate the daily average frequency so that clocks stay within a few seconds of correct time. In practice the nominal frequency is raised or lowered by a specific percentage to maintain synchronization. In the continental European UCTE grid, the deviation between network phase time and UTC is calculated at 08:00 each day in a control center in Switzerland, and the target frequency is then adjusted by up to ±0. Continental Europe, also referred to as mainland Europe or simply the Continent, is the Continent of Europe, explicitly excluding European The Union for the Co-ordination of Transmission of Electricity (UCTE is an association of Electricity distribution network operators in Continental Europe. 02% from 50 Hz as needed, to ensure a long-term frequency average of exactly 3600×24×50 cycles per day is maintained. [9] In North America, whenever the error exceeds 2 seconds for the east, 3 seconds for Texas, or 10 seconds for the west, a correction of ±0. The North American Electric Reliability Corporation (NERC is a Nonprofit corporation based in Princeton NJ which was formed March 28, 2006. 02 Hz (0. 033%) is applied. Time error corrections start and end either on the hour or on the half hour. [10][11] A real-time frequency meter for power generation in the United Kingdom is available online. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located [1] Smaller power systems may not maintain frequency with the same degree of accuracy.

Voltage regulation

To maintain the voltage at the customer's service within the acceptable range, electrical distribution utilities use regulating equipment at electrical substations or along the distribution line. An electrical substation is a subsidiary station of an Electricity generation, transmission and distribution system where Voltage At a substation, the step-down transformer will have an automatic on-load tap changer, allowing the ratio between transmission voltage and distribution voltage to be adjusted in steps. A transformer is a device that transfers Electrical energy from one circuit to another through inductively coupled Electrical conductors For long (several kilometers) rural distribution circuits, automatic voltage regulators may be mounted on poles of the distribution line. These are autotransformers again with on-load tapchangers to adjust the ratio depending on the observed voltage changes. An autotransformer (sometimes called autoformer) is an electrical Transformer with only one winding.

At each customer's service, the step-down transformer has up to five taps to allow some range of adjustment, usually ±5% of the nominal voltage. Since these taps are not automatically controlled, they are only used to adjust the long-term average voltage at the service and do not regulate the voltage seen by the utility customer.

See also

References

  1. ^ CENELEC Harmonization Document HD 472 S1:1988
  2. ^ British Standard BS 7697: Nominal voltages for low voltage public electricity supply systems — (Implementation of HD 472 S1)
  3. ^ ANSI C84. In Physics, the potential difference or pd between two points is the difference of the points' Scalar potential, equivalent to the line integral A power connector is an electrical Connector designed to carry a significant amount of electrical power, usually as DC or low-frequency AC. This article deals with where how and why "three phase" is used A Meter Point Administration Number also known as MPAN, Supply Number or S-Number is a 21 digit reference used in Great Britain to uniquely 1: American National Standard for Electric Power Systems and Equipment—Voltage Ratings (60 Hertz)
  4. ^ CSA C3-235: Preferred Voltage Levels for AC Systems, 0 to 50 000 V
  5. ^ AS60038-2000 Standards Australia - Standard Voltages
  6. ^ SAI Global
  7. ^ Thomas P. Hughes, Networks of Power: Electrification in Western Society 1880-1930, The Johns Hopkins University Press,Baltimore 1983 ISBN 0-8018-2873-2 pg. Established in 1919 the Canadian Standards Association (CSA is a not-for-profit association composed of representatives from government industry and Standards Australia was established in 1922 and is recognised through a Memorandum of Understanding with the Commonwealth Government as the peak non-government standards development body in Australia Thomas Parke Hughes (born in 1929) is an American Historian of Technology 193
  8. ^ Hughes, Networks of Power
  9. ^ Load Frequency Control and Performance
  10. ^ Manual Time Error Correction
  11. ^ Time Error Correction

External links

NercmapJPG|thumb|right|250px|The three major and two minor NERC Interconnections and the nine NERC Regional Reliability Councils
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