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51-573: [REDACTED] Look up tev in Wiktionary, the free dictionary. TEV may refer to: Transient Earth voltage : a term for voltages appearing on the metal work of switchgear due to internal partial discharges TeV , or teraelectronvolt or trillion electron volt, a measure of energy Total enterprise value , a financial measure Total economic value , an economic measure Tracked Electric Vehicles, an open source electric vehicle system proposed by

102-534: A building material . The word "marble" derives from the Ancient Greek μάρμαρον ( mármaron ), from μάρμαρος ( mármaros ), "crystalline rock, shining stone", perhaps from the verb μαρμαίρω ( marmaírō ), "to flash, sparkle, gleam"; R. S. P. Beekes has suggested that a " Pre-Greek origin is probable". This stem is also the ancestor of the English word "marmoreal", meaning "marble-like." While

153-476: A recommended exposure limit (REL) of 10 mg/m total exposure and 5 mg/m respiratory exposure over an 8-hour workday. Dust, debris and temperature fluctuations from working marble can endanger the eye health of employees. For the staff involved in marble processing, it is necessary to provide eye protection equipment, and it is recommended to improve the education of all workers on occupational health risks and strengthen preventive measures. As

204-416: A transformer and switchgear line-up may be combined in one housing, called a unitized substation (USS). According to the latest research by Visiongain, a market research company, the worldwide switchgear market is expected to achieve $ 152.5 billion by 2029 at a CAGR of 5.9%. Growing investment in renewable energy and enhanced demand for safe and secure electrical distribution systems are expected to generate

255-440: A building. For higher voltages (over about 66 kV), switchgear is typically mounted outdoors and insulated by air, although this requires a large amount of space. Gas-insulated switchgear saves space compared with air-insulated equipment, although the equipment cost is higher. Oil insulated switchgear presents an oil spill hazard. Switches may be manually operated or have motor drives to allow for remote control. A switchgear may be

306-486: A de-energized circuit. Oil-filled switchgear equipment allows arc energy to be contained and safely controlled. By the early 20th century, a switchgear line-up would be a metal-enclosed structure with electrically operated switching elements using oil circuit breakers. Today, oil-filled equipment has largely been replaced by air-blast, vacuum, or SF 6 equipment, allowing large currents and power levels to be safely controlled by automatic equipment. High-voltage switchgear

357-441: A fault. Several different classifications of switchgear can be made: A single line-up may incorporate several different types of devices, for example, air-insulated bus, vacuum circuit breakers, and manually operated switches may all exist in the same row of cubicles. Ratings, design, specifications and details of switchgear are set by a multitude of standards. In North America mostly IEEE and ANSI standards are used, much of

408-560: A growth of 12% annually for the 2000–2006 period, compared to 10.5% annually for the 2000–2005 period. The largest dimension marble application is tile. The stone and marble industry is one of the largest industries in Palestine, contributing 20-25% of its total industrial revenues, generating USD $ 400–$ 450 million in revenue annually. The industry employs 15,000–20,000 workers across the West Bank across 1200–1700 facilities, and amounts to 4.5% of

459-682: A key that will allow closing the second switch. Complex schemes are possible. Indoor switchgear can also be type tested for internal arc containment (e.g., IEC 62271-200). This test is important for user safety as modern switchgear is capable of switching large currents. Switchgear is often inspected using thermal imaging to assess the state of the system and predict failures before they occur. Other methods include partial discharge (PD) testing, using either fixed or portable testers, and acoustic emission testing using surface-mounted transducers (for oil equipment) or ultrasonic detectors used in outdoor switchyards. Temperature sensors fitted to cables to

510-471: A load. Switchgear is as old as electricity generation . The first models were very primitive: all components were simply fixed to a wall. Later they were mounted on wooden panels. For reasons of fire protection, the wood was replaced by slate or marble . This led to a further improvement, because the switching and measuring devices could be attached to the front, while the wiring was on the back. Switchgear for lower voltages may be entirely enclosed within

561-630: A potential hazard. Mitigations such as dust filters, or dust suppression are suggested, but more research needs to be carried out on the efficacy of safety measures. In the United States, the Occupational Safety and Health Administration (OSHA) has set the legal limit ( permissible exposure limit ) for marble exposure in the workplace as 15 mg/m total exposure and 5 mg/m respiratory exposure over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set

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612-471: A refrigeration system component The IATA code designator for Teruel Airport See also [ edit ] [REDACTED] Search for "tev" on Misplaced Pages. All pages with titles beginning with TEV All pages with titles containing TEV Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title TEV . If an internal link led you here, you may wish to change

663-433: A remote location without the need to wear a protective arc flash hazard suit. Switchgear systems require continuous maintenance and servicing to remain safe to use and fully optimized to provide such high voltages. Marble In geology , the term marble refers to metamorphosed limestone , but its use in stonemasonry more broadly encompasses unmetamorphosed limestone. Marble is commonly used for sculpture and as

714-485: A simple open-air isolator switch or it may be insulated by some other substance. An effective although more costly form of switchgear is the gas-insulated switchgear (GIS), where the conductors and contacts are insulated by pressurized sulfur hexafluoride gas (SF 6 ). Other common types are oil or vacuum insulated switchgear. The combination of equipment within the switchgear enclosure allows them to interrupt fault currents of thousands of amps. A circuit breaker (within

765-496: A switchgear enclosure) is the primary component that interrupts fault currents. The quenching of the arc when the circuit breaker pulls apart the contacts (disconnects the circuit) requires careful design. Circuit breakers fall into these six types: Oil circuit breakers rely upon the vaporization of some of the oil to blast a jet of oil along the arc's path. The vapor released by the arcing consists of hydrogen gas . Mineral oil has better insulating properties than air. Whenever there

816-425: A typical process using magnesium fluorosilicate (MgSiF 6 ) and hydrochloric acid (HCl) taking place. The resulting calcium hexafluorosilicate (CaSiF 6 ) is bonded to the surface of the marble. This is harder, more glossy and stain resistant compared to the original surface. The other often used method of finishing marble is to polish with oxalic acid (H 2 C 2 O 4 ), an organic acid. The resulting reaction

867-399: Is a rock composed of calcium and magnesium carbonate , mostly white and pink. Common marble varieties are granular limestone or dolomite . The hardness of marble is very high, because the internal structure of the rock is very uniform after long-term natural aging, and the internal stress disappears, so the marble will not be deformed due to temperature, and has strong wear resistance. It

918-421: Is a separation of current-carrying contacts in the oil, the arc in the circuit breaker is initialized at the moment of separation of contacts, and due to this arc the oil is vaporized and decomposed to mostly hydrogen gas and ultimately creates a hydrogen bubble around the electric arc . This highly compressed gas bubble around the turn prevents the re-striking of the arc after the current reaches zero crossing of

969-406: Is a type which combines the components of traditional air-insulated switchgear (AIS) and SF 6 gas-insulated switchgear (GIS) technologies. It is characterized by a compact and modular design, which encompasses several different functions in one module. Circuit breakers with vacuum interrupters have minimal arcing characteristics (as there is nothing to ionize other than the contact material), so

1020-439: Is a very popular building material. The following table is a summary of the features of Marble. White marble has been prized for its use in sculptures since classical times . This preference has to do with its softness, which made it easier to carve, relative isotropy and homogeneity, and a relative resistance to shattering. Also, the low index of refraction of calcite allows light to penetrate 12.7 to 38 millimeters into

1071-533: Is as follows: In this case the calcium oxalate (CaC 2 O 4 ) formed in the reaction is washed away with the slurry, leaving a surface that has not been chemically changed. The haloalkaliphilic methylotrophic bacterium Methylophaga murata was isolated from deteriorating marble in the Kremlin . Bacterial and fungal degradation was detected in four samples of marble from Milan Cathedral ; black Cladosporium attacked dried acrylic resin using melanin. Marble

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1122-602: Is composed of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream. This type of equipment is directly linked to the reliability of the electricity supply. The earliest central power stations used simple open knife switches , mounted on insulating panels of marble or asbestos . Power levels and voltages rapidly escalated, making opening manually operated switches too dangerous for anything other than isolation of

1173-411: Is that with DC there is no "current zero" period. The plasma arc can feed itself by continuing to gasify the contact material. Breakers that use carbon dioxide as the insulating and arc extinguishing medium work on the same principles as a sulfur hexafluoride (SF 6 ) breaker. Because SF 6 is a greenhouse gas more potent than CO 2 , by switching from SF 6 to CO 2 it is possible to reduce

1224-580: Is typically composed of an interlocking mosaic of carbonate crystals . Primary sedimentary textures and structures of the original carbonate rock ( protolith ) have typically been modified or destroyed. Pure white marble is the result of metamorphism of a very pure ( silicate -poor) limestone or dolomite protolith. The characteristic swirls and veins of many colored marble varieties, sometimes called striations , are usually due to various mineral impurities such as clay , silt , sand , iron oxides , or chert which were originally present as grains or layers in

1275-620: The TEV Project Transparent Election Verification Software , open source software for auditing elections Tobacco etch virus , a plant pathogenic virus of the family Potyviridae Tobacco etch virus protease , an enzyme commonly used in biochemistry Today's English Version , a former name for the Good News Bible TEV, a ship prefix for Turbo-electric Vessel , usually with steam driven turbines . Thermal expansion valve ,

1326-485: The dimension stone trade, the term marble is used for any crystalline calcitic rock (and some non-calcitic rocks) useful as building stone. For example, Tennessee marble is really a dense granular fossiliferous gray to pink to maroon Ordovician limestone, that geologists call the Holston Formation . Ashgabat , the capital city of Turkmenistan , was recorded in the 2013 Guinness Book of Records as having

1377-514: The English term "marble" resembles the French marbre , most other European languages (with words like "marmoreal") more closely resemble the original Ancient Greek. Marble is a rock resulting from metamorphism of sedimentary carbonate rocks , most commonly limestone or dolomite . Metamorphism causes variable re-crystallization of the original carbonate mineral grains. The resulting marble rock

1428-468: The arc quenches when it is stretched by a small amount (<2–8 mm). Near zero current the arc is not hot enough to maintain a plasma, and current ceases; the gap can then withstand the rise of voltage. Vacuum circuit breakers are frequently used in modern medium-voltage switchgear to 40,500 volts. Unlike the other types, they are inherently unsuitable for interrupting DC faults. The reason vacuum circuit breakers are unsuitable for breaking high DC voltages

1479-413: The cycle. The oil circuit breaker is one of the oldest types of circuit breakers. Air circuit breakers may use compressed air (puff) or the magnetic force of the arc itself to elongate the arc. As the length of the sustainable arc is dependent on the available voltage, the elongated arc will eventually exhaust itself. Alternatively, the contacts are rapidly swung into a small sealed chamber, the escaping of

1530-423: The device. In the case of a transformer, the circuit breakers on both the primary and secondary would open. A short circuit at the end of a long transmission line appears similar to a normal load, because the impedance of the transmission line limits the fault current. A distance relay detects a fault by comparing the voltage and current on the transmission line. A large current along with a voltage drop indicates

1581-464: The displaced air thus blowing out the arc. Circuit breakers are usually able to terminate all current flow very quickly: typically between 30 ms and 150 ms depending upon the age and construction of the device. Gas (SF 6 ) circuit breakers sometimes stretch the arc using a magnetic field , and then rely upon the dielectric strength of the SF 6 gas to quench the stretched arc. Hybrid switchgear

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1632-487: The excavated material will be waste, this is often then used as chips for flooring or wall finish, and uses for which high-calcium limestone is suitable. Marble sludge waste can be used as a mineral filler in water-based paints. Using ground calcium carbonate as a filler in paint production can improve the brightness, hiding power and application performance of paint, and can also replace expensive pigments such as titanium dioxide . Recycling of marble waste leads to

1683-451: The favorite medium for Greek and Roman sculptors and architects (see classical sculpture ), marble has become a cultural symbol of tradition and refined taste. Its extremely varied and colorful patterns make it a favorite decorative material. Places named after the stone include Marblehead, Massachusetts ; Marblehead, Ohio ; Marble Arch , London; the Sea of Marmara ; India's Marble Rocks ; and

1734-437: The formation of "black-crust" (accumulation of calcium sulphate, nitrates and carbon particles). Vinegar and other acidic solutions should be avoided in the cleaning of marble products. Crystallization refers to a method of imparting a glossy, more durable finish on to a marble floor (CaCO 3 ). It involves polishing the surface with an acidic solution and a steel wool pad on a flooring machine. The chemical reaction below shows

1785-501: The greenhouse gas emissions by 10 tons during the product lifecycle. Circuit breakers and fuses disconnect when current exceeds a predetermined safe level. However they cannot sense other critical faults, such as unbalanced currents—for example, when a transformer winding contacts ground. By themselves, circuit breakers and fuses cannot distinguish between short circuits and high levels of electrical demand. Differential protection depends upon Kirchhoff's current law , which states that

1836-409: The increase. A switchgear assembly has two types of components: One of the basic functions of switchgear is protection, which is interruption of short-circuit and overload fault currents while maintaining service to unaffected circuits. Switchgear also provides isolation of circuits from power supplies. Switchgear is further used to enhance system availability by allowing more than one source to feed

1887-566: The limestone. Green coloration is often due to serpentine resulting from originally magnesium-rich limestone or dolomite with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism. Acids react with the calcium carbonate in marble, producing carbonic acid (which decomposes quickly to CO 2 and H 2 O) and other soluble salts : Outdoor marble statues, gravestones , or other marble structures are damaged by acid rain whether by carbonation , sulfation or

1938-400: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=TEV&oldid=1216518797 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Switchgear In an electric power system , a switchgear

1989-546: The nation's GDP. The vast majority of the industry's exports are to Israel. Marble in the geologic sense does not naturally outcrop in Palestine, and that the vast majority of commercially labeled marble produced in Palestine produced would be geologically considered limestone. Particulate air pollution exposure has been found to be elevated in the marble production industry. Exposure to the dust produced by cutting marble could impair lung function or cause lung disease in workers, such as silicosis . Skin and eye problems are also

2040-406: The rest of the world uses IEC standards, sometimes with local national derivatives or variations. To help ensure safe operation sequences of switchgear, trapped-key interlocking provides predefined scenarios of operation. For example, if only one of two sources of supply are permitted to be connected at a given time, the interlock scheme may require that the first switch must be opened to release

2091-409: The stone before being scattered out, resulting in the characteristic waxy look which brings a lifelike luster to marble sculptures of any kind, which is why many sculptors preferred and still prefer marble for sculpting the human form. Construction marble is a stone which is composed of calcite, dolomite or serpentine that is capable of taking a polish. More generally in construction , specifically

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2142-459: The sum of currents entering or leaving a circuit node must equal zero. Using this principle to implement differential protection, any section of a conductive path may be considered a node. The conductive path could be a transmission line, a winding of a transformer, a winding in a motor, or a winding in the stator of an alternator. This form of protection works best when both ends of the conductive path are physically close to each other. This scheme

2193-566: The switchgear can permanently monitor temperature build-up. SF 6 equipment is invariably fitted with alarms and interlocks to warn of loss of pressure, and to prevent operation if the pressure falls too low. The increasing awareness of dangers associated with high fault levels has resulted in network operators specifying closed-door operations for earth switches and racking breakers. Many European power companies have banned operators from switch rooms while operating. Remote racking systems are available which allow an operator to rack switchgear from

2244-658: The towns of Marble, Minnesota ; Marble, Colorado ; Marble Falls, Texas , and Marble Hill, Manhattan, New York . The Elgin Marbles are marble sculptures from the Parthenon in Athens that are on display in the British Museum . Total world quarrying production in 2019 was approximately 316 million tonnes; however, quarrying waste accounted for 53% of this total production. In the process of marble mining and processing, around half or

2295-642: The widespread exchange of marble objects, including building elements, sculptures, and sarcophagi . There was a significant increase in the distribution of white marble from the late 1st century BC to the end of the 2nd century AD. A gradual decline in distribution started in the third century AD. According to the United States Geological Survey , U.S. domestic marble production in 2006 was 46,400 tons valued at about $ 18.1 million, compared to 72,300 tons valued at $ 18.9 million in 2005. Crushed marble production (for aggregate and industrial uses) in 2006

2346-415: The world's highest concentration of white marble buildings. The extraction of marble is performed by quarrying . Blocks are favoured for most purposes, and can be created through various techniques, including drilling and blasting, water jet and wedge methods. Limestones are often commercially and historically referred to as marble, which differs from the geological definition. In 1998, marble production

2397-719: Was China with a 64% market share, followed by India with 11% and Italy with 5%. White marbles throughout the Mediterranean basin were widely utilized during the Roman period. Extraction centers were unevenly distributed across the Italian Peninsula , mainland Greece , the Aegean Islands , Asia Minor , and smaller hubs like those in the Iberian Peninsula . The need for extensive trade arose due to this imbalance, leading to

2448-465: Was 11.8 million tons valued at $ 116 million, of which 6.5 million tons was finely ground calcium carbonate and the rest was construction aggregate . For comparison, 2005 crushed marble production was 7.76 million tons valued at $ 58.7 million, of which 4.8 million tons was finely ground calcium carbonate and the rest was construction aggregate. U.S. dimension marble demand is about 1.3 million tons. The DSAN World Demand for (finished) Marble Index has shown

2499-447: Was dominated by 4 countries that accounted for almost half of world production of marble and decorative stone. Italy and China were the world leaders, each representing 16% of world production, while Spain and India produced 9% and 8%, respectively. In 2018 Turkey was the world leader in marble export, with 42% share in global marble trade, followed by Italy with 18% and Greece with 10%. The largest importer of marble in 2018

2550-459: Was invented in Great Britain by Charles Hesterman Merz and Bernard Price . Two identical current transformers are used for each winding of a transformer, stator, or other device. The current transformers are placed around opposite ends of a winding. The current through both ends should be identical. A protective relay detects any imbalance in currents, and trips circuit breakers to isolate

2601-556: Was invented at the end of the 19th century for operating motors and other electric machines. The technology has been improved over time and can now be used with voltages up to 1,100 kV. Typically, switchgear in substations is located on both the high- and low-voltage sides of large power transformers . The switchgear on the low-voltage side of the transformers may be located in a building, with medium-voltage circuit breakers for distribution circuits, along with metering, control, and protection equipment. For industrial applications,

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