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60-415: Nessum offers two types of communication: wired (Nessum WIRE) and wireless (Nessum AIR). Nessum WIRE can be used for various types of wires such as power lines , twisted pair wiring, coaxial cables , and telephone lines . The communication distance can range between tens of meters to several kilometers depending on the use case. In addition, when an automatic relay function called multi-hop (ITU-T G.9905)

120-639: A flashover and loss of supply. Oscillatory motion of the physical line is termed conductor gallop or flutter depending on the frequency and amplitude of oscillation. Electric power can be transmitted by underground power cables . Underground cables take up no right-of-way, have lower visibility, and are less affected by weather. However, cables must be insulated. Cable and excavation costs are much higher than overhead construction. Faults in buried transmission lines take longer to locate and repair. In some metropolitan areas, cables are enclosed by metal pipe and insulated with dielectric fluid (usually an oil) that

180-1096: A few centimetres in diameter), much of the current flow is concentrated near the surface due to the skin effect . The center of the conductor carries little current but contributes weight and cost. Thus, multiple parallel cables (called bundle conductors ) are used for higher capacity. Bundle conductors are used at high voltages to reduce energy loss caused by corona discharge . Today, transmission-level voltages are usually 110 kV and above. Lower voltages, such as 66 kV and 33 kV, are usually considered subtransmission voltages, but are occasionally used on long lines with light loads. Voltages less than 33 kV are usually used for distribution . Voltages above 765 kV are considered extra high voltage and require different designs. Overhead transmission wires depend on air for insulation, requiring that lines maintain minimum clearances. Adverse weather conditions, such as high winds and low temperatures, interrupt transmission. Wind speeds as low as 23 knots (43 km/h) can permit conductors to encroach operating clearances, resulting in

240-575: A much smaller benefit than the squared reduction provided by multiplying the voltage. Long-distance transmission is typically done with overhead lines at voltages of 115 to 1,200 kV. At higher voltages, where more than 2,000 kV exists between conductor and ground, corona discharge losses are so large that they can offset the lower resistive losses in the line conductors. Measures to reduce corona losses include larger conductor diameter, hollow cores or conductor bundles. Factors that affect resistance and thus loss include temperature, spiraling, and

300-426: A practice that later became known as distributed generation using large numbers of small generators. Transmission of alternating current (AC) became possible after Lucien Gaulard and John Dixon Gibbs built what they called the secondary generator, an early transformer provided with 1:1 turn ratio and open magnetic circuit, in 1881. The first long distance AC line was 34 kilometres (21 miles) long, built for

360-537: A transformer and alternating current lighting system led Westinghouse to begin installing AC systems later that year. In 1888 the first designs for an AC motor appeared. These were induction motors running on polyphase current, independently invented by Galileo Ferraris and Nikola Tesla . Westinghouse licensed Tesla's design. Practical three-phase motors were designed by Mikhail Dolivo-Dobrovolsky and Charles Eugene Lancelot Brown . Widespread use of such motors were delayed many years by development problems and

420-681: A voluntary association, originally under the name of "HD-PLC Alliance". In October 2023, the HD-PLC Alliance was renamed the Nessum Alliance. Nessum Alliance is a certifying body for compatibility between communication devices that comply with the international standard IEEE 1901-2020. Associated organisations are the Japanese Telecommunication Technology Committee (TTC) The Taiwanese Industrial Technology Research Institute and

480-591: A wide area reduced costs. The most efficient plants could be used to supply varying loads during the day. Reliability was improved and capital costs were reduced, because stand-by generating capacity could be shared over many more customers and a wider area. Remote and low-cost sources of energy, such as hydroelectric power or mine-mouth coal, could be exploited to further lower costs. The 20th century's rapid industrialization made electrical transmission lines and grids critical infrastructure . Interconnection of local generation plants and small distribution networks

540-490: Is a network of power stations , transmission lines, and substations . Energy is usually transmitted within a grid with three-phase AC . 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 four wires or three wires with unequal currents. Higher order phase systems require more than three wires, but deliver little or no benefit. While

600-634: Is a technology research and development institution in Taiwan . It was founded in 1973 and is headquartered in Hsinchu City , Taiwan, with branch offices in the U.S. , Europe , and Japan . Since 1973, ITRI has been a significant driver of Taiwan's economy, especially its tech industry, having contributed to moving Taiwan's industries from labor-intensive to innovation-driven. Its open lab and incubator have fostered emerging industries and startups including UMC and TSMC . In 2020, ITRI launched

660-416: Is also used in submarine power cables (typically longer than 30 miles (50 km)), and in the interchange of power between grids that are not mutually synchronized. HVDC links stabilize power distribution networks where sudden new loads, or blackouts, in one part of a network might otherwise result in synchronization problems and cascading failures . Electricity is transmitted at high voltages to reduce

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720-454: Is called Nessum AIR. It uses magnetic field communication for short range communication. The communication distance can be controlled in the range of a few centimeters to 100 centimeters. Maximum physical speed is 1 Gbps, with an effective speed of 100 Mbps. The physical layer uses Wavelet OFDM (Wavelet Orthogonal Frequency Division Multiplexing), while a guard interval is required in ordinary OFDM systems. The Wavelet OFDM system eliminates

780-571: Is changed with transformers . The voltage is stepped up for transmission, then reduced for local distribution. A wide area synchronous grid , known as an interconnection in North America, directly connects generators delivering AC power with the same relative frequency to many consumers. North America has four major interconnections: Western , Eastern , Quebec and Texas . One grid connects most of continental Europe . Historically, transmission and distribution lines were often owned by

840-668: Is either static or circulated via pumps. If an electric fault damages the pipe and leaks dielectric, liquid nitrogen is used to freeze portions of the pipe to enable draining and repair. This extends the repair period and increases costs. The temperature of the pipe and surroundings are monitored throughout the repair period. Underground lines are limited by their thermal capacity, which permits less overload or re-rating lines. Long underground AC cables have significant capacitance , which reduces their ability to provide useful power beyond 50 miles (80 kilometres). DC cables are not limited in length by their capacitance. Commercial electric power

900-435: Is for high speed applications such as TV, AV, and surveillance cameras. The major technical features include: Source: This is for long-distance applications such as smart meter, building network, factory, energy management, and IoT devices. The major technical features include: Source: Source: We now come to communication speed issues like high-definition video images (4K/8K) or in some cases multi hop technology

960-473: Is improved at higher voltage and lower current. The reduced current reduces heating losses. Joule's first law states that energy losses are proportional to the square of the current. Thus, reducing the current by a factor of two lowers the energy lost to conductor resistance by a factor of four for any given size of conductor. The optimum size of a conductor for a given voltage and current can be estimated by Kelvin's law for conductor size, which states that size

1020-482: Is known as the base load and is generally served by large facilities with constant operating costs, termed firm power . Such facilities are nuclear, coal or hydroelectric, while other energy sources such as concentrated solar thermal and geothermal power have the potential to provide firm power. Renewable energy sources, such as solar photovoltaics, wind, wave, and tidal, are, due to their intermittency, not considered to be firm. The remaining or peak power demand,

1080-579: Is nearly always an aluminum alloy, formed of several strands and possibly reinforced with steel strands. Copper was sometimes used for overhead transmission, but aluminum is lighter, reduces yields only marginally and costs much less. Overhead conductors are supplied by several companies. Conductor material and shapes are regularly improved to increase capacity. Conductor sizes range from 12 mm (#6 American wire gauge ) to 750 mm (1,590,000  circular mils area), with varying resistance and current-carrying capacity . For large conductors (more than

1140-501: Is not enough to reach an isolated and distant PLC terminal. HD-PLC Quatro Core has been designed to solve these problems. This technology is an improvement on the conventional HD-PLC in both communication distance and speed. It achieves to double conventional HD-PLC's communication distance by adopting a communication band of 1/2 or 1/4 of conventional HD-PLC band and achieves to offer a maximum physical line transmission rate of 1 Gbit/s by using an expanded communication band 2 or 4 times

1200-401: Is optimal when the annual cost of energy wasted in resistance is equal to the annual capital charges of providing the conductor. At times of lower interest rates and low commodity costs, Kelvin's law indicates that thicker wires are optimal. Otherwise, thinner conductors are indicated. Since power lines are designed for long-term use, Kelvin's law is used in conjunction with long-term estimates of

1260-406: Is partially dependent on the physical orientation of the lines with respect to each other. Three-phase lines are conventionally strung with phases separated vertically. The mutual inductance seen by a conductor of the phase in the middle of the other two phases is different from the inductance seen on the top/bottom. Unbalanced inductance among the three conductors is problematic because it may force

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1320-998: Is produced at a relatively low voltage between about 2.3 kV and 30 kV, depending on the size of the unit. The voltage is then stepped up by the power station transformer to a higher voltage (115 kV to 765 kV AC) for transmission. In the United States, power transmission is, variously, 230 kV to 500 kV, with less than 230 kV or more than 500 kV as exceptions. The Western Interconnection has two primary interchange voltages: 500 kV AC at 60 Hz, and ±500 kV (1,000 kV net) DC from North to South ( Columbia River to Southern California ) and Northeast to Southwest (Utah to Southern California). The 287.5 kV ( Hoover Dam to Los Angeles line, via Victorville ) and 345 kV ( Arizona Public Service (APS) line) are local standards, both of which were implemented before 500 kV became practical. Transmitting electricity at high voltage reduces

1380-400: Is stepped down before the current is sent to smaller substations. Subtransmission circuits are usually arranged in loops so that a single line failure does not stop service to many customers for more than a short time. Industrial Technology Research Institute The Industrial Technology Research Institute ( ITRI ; Chinese : 工業技術硏究院 ; pinyin : Gōngyè Jìshù Yánjiù Yuàn )

1440-666: Is supplied by peaking power plants , which are typically smaller, faster-responding, and higher cost sources, such as combined cycle or combustion turbine plants typically fueled by natural gas. Long-distance transmission (hundreds of kilometers) is cheap and efficient, with costs of US$ 0.005–0.02 per kWh, compared to annual averaged large producer costs of US$ 0.01–0.025 per kWh, retail rates upwards of US$ 0.10 per kWh, and multiples of retail for instantaneous suppliers at unpredicted high demand moments. New York often buys over 1000 MW of low-cost hydropower from Canada. Local sources (even if more expensive and infrequently used) can protect

1500-411: Is swapped at specially designed transposition towers at regular intervals along the line using various transposition schemes . Subtransmission runs at relatively lower voltages. It is uneconomical to connect all distribution substations to the high main transmission voltage, because that equipment is larger and more expensive. Typically, only larger substations connect with this high voltage. Voltage

1560-425: Is used for each subcarrier, and the optimal number of modulation multi-levels is set according to the conditions of the transmission path, thereby improving transmission efficiency. The frequency band used can be selected from among standardized patterns. The data link layer manages quality of service and other control functions using control frames "beacons" broadcast periodically by the parent to all terminals in

1620-425: Is utilized, a maximum of 10 stages of relay is possible to extend the range, and support various network topologies ( Ring , Star , Bus , MESH ). With a maximum physical speed of 1 Gbps and effective throughput ranging from several Mbps to several hundred Mbps, this technology is used to reduce network construction costs and complexity by utilizing the existing lines or dedicated lines. Nessum wireless communication

1680-465: The I 2 R {\displaystyle I^{2}R} losses are still reduced ten-fold using the higher voltage. While power loss can also be reduced by increasing the wire's conductance (by increasing its cross-sectional area), larger conductors are heavier and more expensive. And since conductance is proportional to cross-sectional area, resistive power loss is only reduced proportionally with increasing cross-sectional area, providing

1740-512: The IEEE Standards Association . This technology is based on HD-PLC , a type of power line communication developed by Panasonic in the early 2000s. HD-PLC was developed for room-to-room transmission of audio and video data at the time, but later began to be used not only for power lines but also for coaxial lines and twisted pair lines, and even for wireless communication. The name "power line communication" did not match

1800-528: The international electricity exhibition in Frankfurt . A 15 kV transmission line, approximately 175 km long, connected Lauffen on the Neckar and Frankfurt. Transmission voltages increased throughout the 20th century. By 1914, fifty-five transmission systems operating at more than 70 kV were in service. The highest voltage then used was 150 kV. Interconnecting multiple generating plants over

1860-712: The resistance define the impedance ) constitute reactive power flow, which transmits no power to the load. These reactive currents, however, cause extra heating losses. The ratio of real power transmitted to the load to apparent power (the product of a circuit's voltage and current, without reference to phase angle) is the power factor . As reactive current increases, reactive power increases and power factor decreases. For transmission systems with low power factor, losses are higher than for systems with high power factor. Utilities add capacitor banks, reactors and other components (such as phase-shifters ; static VAR compensators ; and flexible AC transmission systems , FACTS) throughout

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1920-399: The resistive losses . For example, raising the voltage by a factor of 10 reduces the current by a corresponding factor of 10 and therefore the I 2 R {\displaystyle I^{2}R} losses by a factor of 100, provided the same sized conductors are used in both cases. Even if the conductor size (cross-sectional area) is decreased ten-fold to match the lower current,

1980-506: The skin effect . Resistance increases with temperature. Spiraling, which refers to the way stranded conductors spiral about the center, also contributes to increases in conductor resistance. The skin effect causes the effective resistance to increase at higher AC frequencies. Corona and resistive losses can be estimated using a mathematical model. US transmission and distribution losses were estimated at 6.6% in 1997, 6.5% in 2007 and 5% from 2013 to 2019. In general, losses are estimated from

2040-528: The 1884 International Exhibition of Electricity in Turin, Italy . It was powered by a 2 kV, 130 Hz Siemens & Halske alternator and featured several Gaulard transformers with primary windings connected in series, which fed incandescent lamps. The system proved the feasibility of AC electric power transmission over long distances. The first commercial AC distribution system entered service in 1885 in via dei Cerchi, Rome, Italy , for public lighting. It

2100-419: The 2030 Technology Strategy & Roadmap, which focuses on the development of technology to meet industrial and societal needs by working with domestic and international partners in academia, industry, and the government. In 1982, the new Materials Research Laboratories (MRL) was established under ITRI and Otto C.C. Lin was appointed Founding Director. In 2002, ITRI partnered with Apex Medical and started

2160-519: The AC grid. These stopgaps were slowly replaced as older systems were retired or upgraded. The first transmission of single-phase alternating current using high voltage came in Oregon in 1890 when power was delivered from a hydroelectric plant at Willamette Falls to the city of Portland 14 miles (23 km) down river. The first three-phase alternating current using high voltage took place in 1891 during

2220-664: The Changhua Coastal Industrial Park. StarFab is a tech accelerator founded by ITRI focusing on innovation in the fields of smart manufacturing , smart medical care, smart finance and smart agriculture. It is headquartered in Taipei with an office in the Tainan Science Park . See Honors for more information. In order to recognize outstanding individuals for their contributions to technological advancement, industrial development, and

2280-401: The ability to link all the loads. These included single phase AC systems, poly-phase AC systems, low voltage incandescent lighting, high-voltage arc lighting, and existing DC motors in factories and street cars. In what became a universal system, these technological differences were temporarily bridged via the rotary converters and motor-generators that allowed the legacy systems to connect to

2340-482: The conventional HD-PLC band. This evolution of the standard therefore offers either an extended range in a larger building, at the cost of a lower data rate, or a higher data rate, but achievable over shorter distances than in the previous version of the standard. There are a few strengths of using HD-PLC technology on existing wires. Typical use case include: Nessum Alliance was established in September 2007 as

2400-559: The development of respiratory therapy product series. This was one of Apex Medical's first major collaborations. In 2019, ITRI banned all smartphones and computers made by China's Huawei from their internal network for security reasons. China's Taiwan Affairs Office reacted negatively to the decision with their spokesperson saying that the decision “jeopardizes the mainland and Taiwan’s regular economic cooperation for political purposes". As of 2019, self-driving cars designed by ITRI had accumulated more than 2,000 km of testing in

2460-551: The discrepancy between power produced (as reported by power plants) and power sold; the difference constitutes transmission and distribution losses, assuming no utility theft occurs. As of 1980, the longest cost-effective distance for DC transmission was 7,000 kilometres (4,300 miles). For AC it was 4,000 kilometres (2,500 miles), though US transmission lines are substantially shorter. In any AC line, conductor inductance and capacitance can be significant. Currents that flow solely in reaction to these properties, (which together with

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2520-420: The energy loss due to resistance that occurs over long distances. Power is usually transmitted through overhead power lines . Underground power transmission has a significantly higher installation cost and greater operational limitations, but lowers maintenance costs. Underground transmission is more common in urban areas or environmentally sensitive locations. Electrical energy must typically be generated at

2580-582: The first practical series AC transformer in 1885. Working with the support of George Westinghouse , in 1886 he demonstrated a transformer-based AC lighting system in Great Barrington, Massachusetts . It was powered by a steam engine-driven 500 V Siemens generator. Voltage was stepped down to 100 volts using the Stanley transformer to power incandescent lamps at 23 businesses over 4,000 feet (1,200 m). This practical demonstration of

2640-409: The fraction of energy lost to Joule heating , which varies by conductor type, the current, and the transmission distance. For example, a 100 miles (160 km) span at 765 kV carrying 1000 MW of power can have losses of 0.5% to 1.1%. A 345 kV line carrying the same load across the same distance has losses of 4.2%. For a given amount of power, a higher voltage reduces the current and thus

2700-433: The guard interval and increases the occupancy rate of the data portion, thereby achieving high efficiency. In addition, due to the bandwidth limitation of each subcarrier, the level of sidelobes is set low, which facilitates the formation of spectral notches. This minimizes interference with existing systems and allows for flexible compliance with frequency utilization regulations. Furthermore, Pulse-Amplitude Modulation (PAM)

2760-486: The local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution . The combined transmission and distribution network is part of electricity delivery , known as the electrical grid . Efficient long-distance transmission of electric power requires high voltages . This reduces the losses produced by strong currents . Transmission lines use either alternating current (AC) or direct current (DC). The voltage level

2820-451: The middle line to carry a disproportionate amount of the total power transmitted. Similarly, an unbalanced load may occur if one line is consistently closest to the ground and operates at a lower impedance. Because of this phenomenon, conductors must be periodically transposed along the line so that each phase sees equal time in each relative position to balance out the mutual inductance seen by all three phases. To accomplish this, line position

2880-434: The network. The basic media access methods are Carrier-Sense Multiple Access with Collision Avoidance ( CSMA/CA ) and Dynamic Virtual Token Passing (DVTP), which dynamically assign transmission rights to terminals in the network and avoid collisions, The system uses a collision avoidance mechanism. There are essentially two different types of HD-PLC: HD-PLC Complete and HD-PLC Multi-hop. They are incompatible. Source: This

2940-528: The power supply from weather and other disasters that can disconnect distant suppliers. Hydro and wind sources cannot be moved closer to big cities, and solar costs are lowest in remote areas where local power needs are nominal. Connection costs can determine whether any particular renewable alternative is economically realistic. Costs can be prohibitive for transmission lines, but high capacity, long distance super grid transmission network costs could be recovered with modest usage fees. At power stations , power

3000-467: The price of copper and aluminum as well as interest rates. Higher voltage is achieved in AC circuits by using a step-up transformer . High-voltage direct current (HVDC) systems require relatively costly conversion equipment that may be economically justified for particular projects such as submarine cables and longer distance high capacity point-to-point transmission. HVDC is necessary for sending energy between unsynchronized grids. A transmission grid

3060-514: The price of generating capacity is high, energy demand is variable, making it often cheaper to import needed power than to generate it locally. Because loads often rise and fall together across large areas, power often comes from distant sources. Because of the economic benefits of load sharing, wide area transmission grids may span countries and even continents. Interconnections between producers and consumers enables power to flow even if some links are inoperative. The slowly varying portion of demand

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3120-409: The reality of the situation. In September 2023, Panasonic Holdings Corporation changed the name of HD-PLC to Nessum. Power lines Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant , to an electrical substation . The interconnected lines that facilitate this movement form a transmission network . This is distinct from

3180-446: The risk of such a failure by providing multiple redundant , alternative routes for power to flow should such shutdowns occur. Transmission companies determine the maximum reliable capacity of each line (ordinarily less than its physical or thermal limit) to ensure that spare capacity is available in the event of a failure in another part of the network. High-voltage overhead conductors are not covered by insulation. The conductor material

3240-500: The same company, but starting in the 1990s, many countries liberalized the regulation of the electricity market in ways that led to separate companies handling transmission and distribution. Most North American transmission lines are high-voltage three-phase AC, although single phase AC is sometimes used in railway electrification systems . DC technology is used for greater efficiency over longer distances, typically hundreds of miles. High-voltage direct current (HVDC) technology

3300-639: The same rate at which it is consumed. A sophisticated control system is required to ensure that power generation closely matches demand. If demand exceeds supply, the imbalance can cause generation plant(s) and transmission equipment to automatically disconnect or shut down to prevent damage. In the worst case, this may lead to a cascading series of shutdowns and a major regional blackout . The US Northeast faced blackouts in 1965 , 1977 , 2003 , and major blackouts in other US regions in 1996 and 2011 . Electric transmission networks are interconnected into regional, national, and even continent-wide networks to reduce

3360-628: The scarcity of polyphase power systems needed to power them. In the late 1880s and early 1890s smaller electric companies merged into larger corporations such as Ganz and AEG in Europe and General Electric and Westinghouse Electric in the US. These companies developed AC systems, but the technical difference between direct and alternating current systems required a much longer technical merger. Alternating current's economies of scale with large generating plants and long-distance transmission slowly added

3420-409: The system help to compensate for the reactive power flow, reduce the losses in power transmission and stabilize system voltages. These measures are collectively called 'reactive support'. Current flowing through transmission lines induces a magnetic field that surrounds the lines of each phase and affects the inductance of the surrounding conductors of other phases. The conductors' mutual inductance

3480-452: Was initially transmitted at the same voltage used by lighting and mechanical loads. This restricted the distance between generating plant and loads. In 1882, DC voltage could not easily be increased 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. Thus, generators were sited near their loads,

3540-648: Was powered by two Siemens & Halske alternators rated 30 hp (22 kW), 2 kV at 120 Hz and used 19 km of cables and 200 parallel-connected 2 kV to 20 V step-down transformers provided with a closed magnetic circuit, one for each lamp. A few months later it was followed by the first British AC system, serving Grosvenor Gallery . It also featured Siemens alternators and 2.4 kV to 100 V step-down transformers – one per user – with shunt-connected primaries. Working to improve what he considered an impractical Gaulard-Gibbs design, electrical engineer William Stanley, Jr. developed

3600-426: Was spurred by World War I , when large electrical generating plants were built by governments to power munitions factories. These networks use components such as power lines, cables, circuit breakers , switches and transformers . The transmission network is usually administered on a regional basis by an entity such as a regional transmission organization or transmission system operator . Transmission efficiency

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