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Article: Damper winding. The damper winding (also amortisseur winding) is a squirrel-cage-like winding on the rotor of a typical synchronous electric machine. It is used to dampen the transient oscillations and facilitate the start-up operation. Since the design of a damper winding is similar to that of a asynchronous ... | Wikipedia - Damper winding - Summary | 304 | 1,411 | null |
Section: In electronics. Power semiconductor devices have a maximum power dissipation rating usually quoted at a case temperature of 25 °C (77 °F). The datasheet for the device also includes a derating curve which indicates how much a device will dissipate without getting damaged at any given case temperature, and this... | Wikipedia - Derating - In electronics | 313 | 1,496 | null |
Section: Electromagnetic field perspective. For time-varying electromagnetic fields, the electromagnetic energy is typically viewed as waves propagating either through free space, in a transmission line, in a microstrip line, or through a waveguide. Dielectrics are often used in all of these environments to mechanicall... | Wikipedia - Dielectric loss - Electromagnetic field perspective | 185 | 967 | null |
The permittivity can have real and imaginary components (the latter excluding σ effects, see below) such that ε = ε ′ − j ε ″ . {\displaystyle \varepsilon =\varepsilon '-j\varepsilon ''.} If we assume that we have a wave function such that E = E o e j ω t , {\displaystyle \mathbf {E} =\mathbf {E} _{o}e^{j\omega t},} th... | Wikipedia - Dielectric loss - Electromagnetic field perspective | 324 | 1,034 | null |
Section: Electromagnetic field perspective > Loss tangent. The loss tangent is then defined as the ratio (or angle in a complex plane) of the lossy reaction to the electric field E in the curl equation to the lossless reaction: tan δ = ω ε ″ + σ ω ε ′ . {\displaystyle \tan \delta ={\frac {\omega \varepsilon ''+\sigma... | Wikipedia - Dielectric loss - Electromagnetic field perspective > Loss tangent | 272 | 861 | null |
Also, tan δ ≈ δ for small δ. E = E o e − j k ( 1 − j tan δ 2 ) z = E o e − k z tan δ 2 e − j k z , {\displaystyle E=E_{o}e^{-jk\left(1-j{\frac {\tan \delta }{2}}\right)z}=E_{o}e^{-kz{\frac {\tan \delta }{2}}}e^{-jkz},} Since power is electric field intensity squared, it turns out that the power decays with propagat... | Wikipedia - Dielectric loss - Electromagnetic field perspective > Loss tangent | 282 | 855 | null |
Also, a similar analysis could be applied to the magnetic permeability where μ = μ ′ − j μ ″ , {\displaystyle \mu =\mu '-j\mu '',} with the subsequent definition of a magnetic loss tangent tan δ m = μ ″ μ ′ . {\displaystyle \tan \delta _{m}={\frac {\mu ''}{\mu '}}.} The electric loss tangent can be similarly defined:... | Wikipedia - Dielectric loss - Electromagnetic field perspective > Loss tangent | 168 | 516 | null |
Section: Discrete circuit perspective. A capacitor is a discrete electrical circuit component typically made of a dielectric placed between conductors. One lumped element model of a capacitor includes a lossless ideal capacitor in series with a resistor termed the equivalent series resistance (ESR), as shown in the fig... | Wikipedia - Dielectric loss - Discrete circuit perspective | 339 | 1,416 | null |
When representing the electrical circuit parameters as vectors in a complex plane, known as phasors, a capacitor's loss tangent is equal to the tangent of the angle between the capacitor's impedance vector and the negative reactive axis, as shown in the adjacent diagram. The loss tangent is then tan δ = E S R | X c |... | Wikipedia - Dielectric loss - Discrete circuit perspective | 271 | 887 | null |
Article: Direct current. Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The ele... | Wikipedia - Direct current - Summary | 274 | 1,389 | null |
Section: History. Direct current was produced in 1800 by Italian physicist Alessandro Volta's battery, his Voltaic pile. The nature of how current flowed was not yet understood. French physicist André-Marie Ampère conjectured that current travelled in one direction from positive to negative. When French instrument make... | Wikipedia - Direct current - History | 339 | 1,760 | null |
Section: Various definitions. The term DC is used to refer to power systems that use only one electrical polarity of voltage or current, and to refer to the constant, zero-frequency, or slowly varying local mean value of a voltage or current. For example, the voltage across a DC voltage source is constant as is the cur... | Wikipedia - Direct current - Various definitions | 232 | 1,096 | null |
Section: Circuits. A direct current circuit is an electrical circuit that consists of any combination of constant voltage sources, constant current sources, and resistors. In this case, the circuit voltages and currents are independent of time. A particular circuit voltage or current does not depend on the past value o... | Wikipedia - Direct current - Circuits | 339 | 1,656 | null |
Section: Applications > Automotive. Most automotive applications use DC. An automotive battery provides power for engine starting, lighting, the ignition system, the climate controls, and the infotainment system among others. The alternator is an AC device which uses a rectifier to produce DC for battery charging. Most... | Wikipedia - Direct current - Applications > Automotive | 270 | 1,377 | null |
Section: Explanation. Electrical potential energy is dissipated in all dielectric materials, usually in the form of heat. In a capacitor made of a dielectric placed between conductors, the typical lumped element model includes a lossless ideal capacitor in series with a resistor termed the equivalent series resistance ... | Wikipedia - Dissipation factor - Explanation | 341 | 1,323 | null |
For the case of the conduction electrons being the dominant loss, then ESR = σ ε ω 2 C {\displaystyle {\text{ESR}}={\frac {\sigma }{\varepsilon \omega ^{2}C}}} where σ {\displaystyle \sigma } is the dielectric's bulk conductivity, ε {\displaystyle \varepsilon } is the lossless permittivity of the dielectric, and ω = 2 ... | Wikipedia - Dissipation factor - Explanation | 387 | 1,151 | null |
If the capacitor is used in an AC circuit, the dissipation factor due to the non-ideal capacitor is expressed as the ratio of the resistive power loss in the ESR to the reactive power oscillating in the capacitor, or DF = i 2 ESR i 2 | X c | = ω C ESR = σ ε ω = 1 Q {\displaystyle {\text{DF}}={\frac {i^{2}{\text{ESR}}}{... | Wikipedia - Dissipation factor - Explanation | 478 | 1,325 | null |
This gives rise to the parameter known as the loss tangent tan δ where 1 Q = tan ( δ ) = ESR | X c | = DF {\displaystyle {\frac {1}{Q}}=\tan(\delta )={\frac {\text{ESR}}{\left|X_{c}\right|}}={\text{DF}}} Alternatively, ESR {\displaystyle {\text{ESR}}} can be derived from frequency at which loss tangent was determined... | Wikipedia - Dissipation factor - Explanation | 330 | 920 | null |
Article: Duality (electrical circuits). In electrical engineering, electrical terms are associated into pairs called duals. A dual of a relationship is formed by interchanging voltage and current in an expression. The dual expression thus produced is of the same form, and the reason that the dual is always a valid stat... | Wikipedia - Duality (electrical circuits) - Summary | 163 | 741 | null |
Section: Examples > Constitutive relations. Resistor and conductor (Ohm's law) v = i R ⟺ i = v G {\displaystyle v=iR\iff i=vG\,} Capacitor and inductor – differential form i C = C d d t v C ⟺ v L = L d d t i L {\displaystyle i_{C}=C{\frac {d}{dt}}v_{C}\iff v_{L}=L{\frac {d}{dt}}i_{L}} Capacitor and inductor – integral ... | Wikipedia - Duality (electrical circuits) - Examples > Constitutive relations | 281 | 550 | null |
Section: Examples > Impedance and admittance. Resistor and conductor Z R = R ⟺ Y G = G {\displaystyle Z_{R}=R\iff Y_{G}=G} Z G = 1 G ⟺ Y R = 1 R {\displaystyle Z_{G}={1 \over G}\iff Y_{R}={1 \over R}} Capacitor and inductor Z C = 1 C s ⟺ Y L = 1 L s {\displaystyle Z_{C}={1 \over Cs}\iff Y_{L}={1 \over Ls}} Z L = L s ⟺ ... | Wikipedia - Duality (electrical circuits) - Examples > Impedance and admittance | 175 | 367 | null |
Article: Duty cycle. A duty cycle or power cycle is the fraction of one period in which a signal or system is active. Duty cycle is commonly expressed as a percentage or a ratio. A period is the time it takes for a signal to complete an on-and-off cycle. As a formula, a duty cycle (%) may be expressed as: D = P W T × 1... | Wikipedia - Duty cycle - Summary | 342 | 1,286 | null |
Section: Applications > Electrical and electronics. In electronics, duty cycle is the percentage of the ratio of pulse duration, or pulse width (PW) to the total period (T) of the waveform. It is generally used to represent time duration of a pulse when it is high (1). In digital electronics, signals are used in rectan... | Wikipedia - Duty cycle - Applications > Electrical and electronics | 323 | 1,395 | null |
Section: Mark–space ratio. Mark–space ratio, or mark-to-space ratio, is another term for the same concept, to describe the temporal relationship between two alternating periods of a waveform. However, whereas the duty cycle relates the duration of one period to the duration of the entire cycle, the mark–space ratio rel... | Wikipedia - Duty cycle - Mark–space ratio | 186 | 642 | null |
Section: Scope of undergraduate education. The degree generally includes units covering physics, mathematics, project management and specific topics in electrical and electronics engineering. Initially such topics cover most, if not all, of the sub fields of electrical engineering. Students then choose to specialize in... | Wikipedia - Education and training of electrical and electronics engineers - Scope of undergraduate education | 177 | 1,012 | null |
Section: Typical electrical/electronics engineering undergraduate syllabus > Electronic devices and circuits. Electronic Devices: Energy bands in silicon, intrinsic and extrinsic silicon. Carrier transport in silicon: diffusion current, drift current, mobility, resistivity. Generation and recombination of carriers. p-n... | Wikipedia - Education and training of electrical and electronics engineers - Typical electrical/electronics engineering undergraduate syllabus > Electronic devices and circuits | 345 | 1,442 | null |
Section: Certification. The advantages of certification vary depending upon location. For example, in the United States and Canada "only a licensed engineer may...seal engineering work for public and private clients". This requirement is enforced by state and provincial legislation such as Quebec's Engineers Act. In ot... | Wikipedia - Education and training of electrical and electronics engineers - Certification | 280 | 1,566 | null |
Article: Electric power distribution. Electric power distribution is the final stage in the delivery of electricity. Electricity is carried from the transmission system to individual consumers. Distribution substations connect to the transmission system and lower the transmission voltage to medium voltage ranging betwe... | Wikipedia - Electric power distribution - Summary | 344 | 2,022 | null |
Section: History. Electric power distribution become necessary only in the 1880s, when electricity started being generated at power stations. Until then, electricity was usually generated where it was used. The first power-distribution systems installed in European and US cities were used to supply lighting: arc lighti... | Wikipedia - Electric power distribution - History | 301 | 1,491 | null |
Section: History > Introduction of the transformer. The problem of transmitting electricity over longer distances became a recognized engineering roadblock to electric power distribution, with many less-than-satisfactory solutions tested by lighting companies. But the mid-1880s saw a breakthrough with the development o... | Wikipedia - Electric power distribution - History > Introduction of the transformer | 343 | 1,918 | null |
Section: Generation and transmission. Electric power begins at a generating station, where the potential difference can be as high as 33,000 volts. AC is usually used. Users of large amounts of DC power such as some railway electrification systems, telephone exchanges and industrial processes such as aluminium smelting... | Wikipedia - Electric power distribution - Generation and transmission | 274 | 1,431 | null |
Section: Primary distribution > Network configurations. Distribution networks are divided into two types, radial or network. A radial system is arranged like a tree where each customer has one source of supply. A network system has multiple sources of supply operating in parallel. Spot networks are used for concentrate... | Wikipedia - Electric power distribution - Primary distribution > Network configurations | 310 | 1,731 | null |
Section: Primary distribution > Rural services. Rural electrification systems tend to use higher distribution voltages because of the longer distances covered by distribution lines (see Rural Electrification Administration). 7.2, 12.47, 25, and 34.5 kV distribution is common in the United States; 11 kV and 33 kV are co... | Wikipedia - Electric power distribution - Primary distribution > Rural services | 296 | 1,450 | null |
Section: Secondary distribution. Electricity is delivered at a frequency of either 50 or 60 Hz, depending on the region. It is delivered to domestic customers as single-phase electric power. In some countries as in Europe a three phase supply may be made available for larger properties. Seen with an oscilloscope, the d... | Wikipedia - Electric power distribution - Secondary distribution | 246 | 1,171 | null |
Section: Secondary distribution > Regional variations > 220–240 volt systems. Most of the world uses 50 Hz 220 or 230 V single phase, or 400 V three-phase for residential and light industrial services. In this system, the primary distribution network supplies a few substations per area, and the 230 V / 400 V power from... | Wikipedia - Electric power distribution - Secondary distribution > Regional variations > 220–240 volt systems | 304 | 1,434 | null |
Section: Secondary distribution > Regional variations > 100–120 volt systems. Most of the Americas use 60 Hz AC, the 120/240 volt split-phase system domestically and three phase for larger installations. North American transformers usually power homes at 240 volts, similar to Europe's 230 volts. It is the split-phase t... | Wikipedia - Electric power distribution - Secondary distribution > Regional variations > 100–120 volt systems | 344 | 1,582 | null |
Article: Electric power transmission. 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 the local wiring between high-... | Wikipedia - Electric power transmission - Summary | 254 | 1,439 | null |
Section: System. 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 is also u... | Wikipedia - Electric power transmission - System | 345 | 1,877 | null |
Section: System > Overhead. High-voltage overhead conductors are not covered by insulation. The conductor material is nearly always an aluminium 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 ... | Wikipedia - Electric power transmission - System > Overhead | 343 | 1,772 | null |
Section: System > Underground. 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 tr... | Wikipedia - Electric power transmission - System > Underground | 215 | 1,124 | null |
Section: History. Commercial electric power 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, lig... | Wikipedia - Electric power transmission - History | 329 | 1,685 | null |
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 Wi... | Wikipedia - Electric power transmission - History | 337 | 1,701 | null |
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 the ability to link all the loads. These included s... | Wikipedia - Electric power transmission - History | 341 | 1,855 | null |
Section: Bulk transmission. 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 is i... | Wikipedia - Electric power transmission - Bulk transmission | 335 | 1,779 | null |
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 ... | Wikipedia - Electric power transmission - Bulk transmission | 302 | 1,581 | null |
The remaining or peak power demand, 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... | Wikipedia - Electric power transmission - Bulk transmission | 243 | 1,185 | null |
Section: Bulk transmission > Grid input. At power stations, power 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, p... | Wikipedia - Electric power transmission - Bulk transmission > Grid input | 195 | 855 | null |
Section: Bulk transmission > Losses. Transmitting electricity at high voltage reduces 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 34... | Wikipedia - Electric power transmission - Bulk transmission > Losses | 314 | 1,436 | null |
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... | Wikipedia - Electric power transmission - Bulk transmission > Losses | 329 | 1,682 | null |
Section: Bulk transmission > Transposition. 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 is partially dependent on the physical orientation of the lin... | Wikipedia - Electric power transmission - Bulk transmission > Transposition | 235 | 1,242 | null |
Section: Bulk transmission > Subtransmission. 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. Volta... | Wikipedia - Electric power transmission - Bulk transmission > Subtransmission | 301 | 1,465 | null |
Section: Advantage of high-voltage transmission. High-voltage power transmission allows for lesser resistive losses over long distances. This efficiency delivers a larger proportion of the generated power to the loads. In a simplified model, the grid delivers electricity from an ideal voltage source with voltage V {\di... | Wikipedia - Electric power transmission - Advantage of high-voltage transmission | 188 | 795 | null |
If the resistances are in series with no intervening transformer, the circuit acts as a voltage divider, because the same current I = V R + R C {\displaystyle I={\frac {V}{R+R_{C}}}} runs through the wire resistance and the powered device. As a consequence, the useful power (at the point of consumption) is: P R = V 2 ×... | Wikipedia - Electric power transmission - Advantage of high-voltage transmission | 366 | 1,028 | null |
As a consequence, the useful power (at the point of consumption) is: P R = V 2 × I = V R R + R C × V R + R C = R R + R C × V 2 R + R C = R R + R C P V {\displaystyle P_{R}=V_{2}\times I=V{\frac {R}{R+R_{C}}}\times {\frac {V}{R+R_{C}}}={\frac {R}{R+R_{C}}}\times {\frac {V^{2}}{R+R_{C}}}={\frac {R}{R+R_{C}}}P_{V}} Should... | Wikipedia - Electric power transmission - Advantage of high-voltage transmission | 495 | 1,101 | null |
The useful power is then: P R = V 2 × I 2 = a 2 R × V 2 ( a 2 R + R C ) 2 = a 2 R a 2 R + R C P V = R R + R C / a 2 P V {\displaystyle P_{R}=V_{2}\times I_{2}={\frac {a^{2}R\times V^{2}}{(a^{2}R+R_{C})^{2}}}={\frac {a^{2}R}{a^{2}R+R_{C}}}P_{V}={\frac {R}{R+R_{C}/a^{2}}}P_{V}} For a > 1 {\displaystyle a>1} (i.e. convers... | Wikipedia - Electric power transmission - Advantage of high-voltage transmission | 235 | 514 | null |
Section: Modeling. The terminal characteristics of the transmission line are the voltage and current at the sending (S) and receiving (R) ends. The transmission line can be modeled as a black box and a 2 by 2 transmission matrix is used to model its behavior, as follows: [ V S I S ] = [ A B C D ] [ V R I R ] {\displays... | Wikipedia - Electric power transmission - Modeling | 345 | 1,123 | null |
Section: Modeling > Lossless line. The lossless line approximation is the least accurate; it is typically used on short lines where the inductance is much greater than the resistance. For this approximation, the voltage and current are identical at the sending and receiving ends. The characteristic impedance is pure re... | Wikipedia - Electric power transmission - Modeling > Lossless line | 163 | 785 | null |
Section: Modeling > Short line. The short line approximation is normally used for lines shorter than 80 km (50 mi). There, only a series impedance Z is considered, while C and G are ignored. The final result is that A = D = 1 per unit, B = Z Ohms, and C = 0. The associated transition matrix for this approximation is th... | Wikipedia - Electric power transmission - Modeling > Short line | 208 | 556 | null |
Section: Modeling > Medium line. The medium line approximation is used for lines running between 80 and 250 km (50 and 155 mi). The series impedance and the shunt (current leak) conductance are considered, placing half of the shunt conductance at each end of the line. This circuit is often referred to as a nominal π (p... | Wikipedia - Electric power transmission - Modeling > Medium line | 252 | 857 | null |
Section: Modeling > Long line. The long line model is used when a higher degree of accuracy is needed or when the line under consideration is more than 250 km (160 mi) long. Series resistance and shunt conductance are considered to be distributed parameters, such that each differential length of the line has a correspo... | Wikipedia - Electric power transmission - Modeling > Long line | 286 | 1,003 | null |
Section: High-voltage direct current. 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 transmitted over very long distances, the power lost in AC transmission becomes appreciable and it is less... | Wikipedia - Electric power transmission - High-voltage direct current | 347 | 1,708 | null |
A DC link therefore stabilizes the AC grid at either end, since power flow and phase angle can then be controlled independently. As an example, to adjust the flow of AC power on a hypothetical line between Seattle and Boston would require adjustment of the relative phase of the two regional electrical grids. This is an... | Wikipedia - Electric power transmission - High-voltage direct current | 200 | 947 | null |
Section: Capacity. The amount of power that can be sent over a transmission line varies with the length of the line. The heating of short line conductors due to line losses sets a thermal limit. If too much current is drawn, conductors may sag too close to the ground, or conductors and equipment may overheat. For inter... | Wikipedia - Electric power transmission - Capacity | 348 | 1,815 | null |
Section: Capacity > Reconductoring. Some utilities have embraced reconductoring to handle the increase in electricity production. Reconductoring is the replacement-in-place of existing transmission lines with higher-capacity lines. Adding transmission lines is difficult due to cost, permit intervals, and local oppositi... | Wikipedia - Electric power transmission - Capacity > Reconductoring | 342 | 1,796 | null |
Section: Control > Load balancing. The transmission system provides for base load and peak load capability, with margins for safety and fault tolerance. Peak load times vary by region largely due to the industry mix. In hot and cold climates home air conditioning and heating loads affect the overall load. They are typi... | Wikipedia - Electric power transmission - Control > Load balancing | 339 | 1,870 | null |
Section: Communications. Grid operators require reliable communications to manage the grid and associated generation and distribution facilities. Fault-sensing protective relays at each end of the line must communicate to monitor the flow of power so that faulted conductors or equipment can be quickly de-energized and ... | Wikipedia - Electric power transmission - Communications | 301 | 1,669 | null |
Section: Market structure. Electricity transmission is generally considered to be a natural monopoly, but one that is not inherently linked to generation. Many countries regulate transmission separately from generation. Spain was the first country to establish a regional transmission organization. In that country, tran... | Wikipedia - Electric power transmission - Market structure | 306 | 1,650 | null |
Merchant transmission projects in the United States include the Cross Sound Cable from Shoreham, New York to New Haven, Connecticut, Neptune RTS Transmission Line from Sayreville, New Jersey, to New Bridge, New York, and Path 15 in California. Additional projects are in development or have been proposed throughout the ... | Wikipedia - Electric power transmission - Market structure | 250 | 1,284 | null |
Section: Health concerns. Mainstream scientific evidence suggests that low-power, low-frequency, electromagnetic radiation associated with household currents and high transmission power lines does not constitute a short- or long-term health hazard. Some studies failed to find any link between living near power lines an... | Wikipedia - Electric power transmission - Health concerns | 329 | 1,748 | null |
Public utility commissions typically do not comment on health impacts. Biological effects have been established for acute high level exposure to magnetic fields above 100 μT (1 G) (1,000 mG). In a residential setting, one study reported "limited evidence of carcinogenicity in humans and less than sufficient evidence fo... | Wikipedia - Electric power transmission - Health concerns | 247 | 1,064 | null |
Section: Specialized transmission > Superconducting cables. High-temperature superconductors (HTS) promise to revolutionize power distribution by providing lossless transmission. The development of superconductors with transition temperatures higher than the boiling point of liquid nitrogen has made the concept of supe... | Wikipedia - Electric power transmission - Specialized transmission > Superconducting cables | 164 | 888 | null |
Section: Specialized transmission > Wireless power transmission. Both Nikola Tesla and Hidetsugu Yagi attempted to devise systems for large scale wireless power transmission in the late 1800s and early 1900s, without commercial success. In November 2009, LaserMotive won the NASA 2009 Power Beaming Challenge by powering... | Wikipedia - Electric power transmission - Specialized transmission > Wireless power transmission | 168 | 924 | null |
Highest towers: Yangtze River Crossing (China) (height: 345 m or 1,132 ft) Longest power line: Inga-Shaba (Democratic Republic of Congo) (length: 1,700 kilometres or 1,056 miles) Longest span of power line: 5,376 m (17,638 ft) at Ameralik Span (Greenland, Denmark) Longest submarine cables: North Sea Link, (Norway/Unite... | Wikipedia - Electric power transmission - Records | 234 | 945 | null |
Article: Electrical capacitance tomography. Electrical capacitance tomography (ECT) is a method for determination of the dielectric permittivity distribution in the interior of an object from external capacitance measurements. It is a close relative of electrical impedance tomography and is proposed as a method for ind... | Wikipedia - Electrical capacitance tomography - Summary | 227 | 1,137 | null |
Article: Electrical drawing. An electrical drawing is a type of technical drawing that shows information about power, lighting, and communication for an engineering or architectural project. Any electrical working drawing consists of "lines, symbols, dimensions, and notations to accurately convey an engineering's desig... | Wikipedia - Electrical drawing - Summary | 176 | 1,050 | null |
Article: Electrical efficiency. The efficiency of a system in electronics and electrical engineering is defined as useful power output divided by the total electrical power consumed (a fractional expression), typically denoted by the Greek small letter eta (η – ήτα). E f f i c i e n c y = U s e f u l p o w e r o u t p ... | Wikipedia - Electrical efficiency - Summary | 237 | 970 | null |
Section: Efficiency of typical electrical devices. Efficiency should not be confused with effectiveness: a system that wastes most of its input power but produces exactly what it is meant to is effective but not efficient. The term "efficiency" makes sense only in reference to the wanted effect. A light bulb, for examp... | Wikipedia - Electrical efficiency - Efficiency of typical electrical devices | 271 | 1,289 | null |
Section: Education > Coursework > Bachelor's degree. Bachelor's degree programs emphasize the analysis, design, and implementation of electrical/electronic systems. Some programs may focus on a specific sub-discipline, such as control systems or communications systems, while others may take a broader approach, introduc... | Wikipedia - Electrical engineering technology - Education > Coursework > Bachelor's degree | 293 | 1,569 | null |
Article: Electrical device. Electrical devices or electric devices are devices that functionally rely on electric energy (AC or DC) to operate their core parts (electric motors, transformers, lighting, rechargeable batteries, control electronics). They can be contrasted with traditional mechanical devices which depend ... | Wikipedia - Electrical device - Summary | 227 | 1,321 | null |
Article: Electrical network. An electrical network is an interconnection of electrical components (e.g., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage sources, current sources, resistances, inductances, capacit... | Wikipedia - Electrical network - Summary | 246 | 1,214 | null |
Section: Classification > By linearity. Linear electrical networks, a special type consisting only of sources (voltage or current), linear lumped elements (resistors, capacitors, inductors), and linear distributed elements (transmission lines), have the property that signals are linearly superimposable. They are thus m... | Wikipedia - Electrical network - Classification > By linearity | 150 | 727 | null |
Section: Classification > By lumpiness. Discrete passive components (resistors, capacitors and inductors) are called lumped elements because all of their, respectively, resistance, capacitance and inductance is assumed to be located ("lumped") at one place. This design philosophy is called the lumped-element model and ... | Wikipedia - Electrical network - Classification > By lumpiness | 194 | 962 | null |
Section: Applying electrical laws. A number of electrical laws apply to all linear resistive networks. These include: Kirchhoff's current law: The sum of all currents entering a node is equal to the sum of all currents leaving the node. Kirchhoff's voltage law: The directed sum of the electrical potential differences a... | Wikipedia - Electrical network - Applying electrical laws | 257 | 1,331 | null |
Section: Physiological effects of electricity. Electrical shocks on humans can lead to permanent disabilities or death. Size, frequency and duration of the electrical current affect the damage. The effects from electric shock can be: stopping the heart beating properly, preventing the person from breathing, causing mus... | Wikipedia - Electrical safety standards - Physiological effects of electricity | 152 | 864 | null |
Section: Electrical safety standards. Australia – Australian Standards AS/NZS 3000:2007, AS/NZS 3012:2010, AS/NZS 3017:2007, AS/NZS 3760:2010, AS/NZS 4836:2011 Brazil – National Regulation – NR10 Bulgaria – Български Държавен Стандарт – (On English:Bulgarian state standard) – БДС 12.2.096:1986 China – GB4943, GB17625, ... | Wikipedia - Electrical safety standards - Electrical safety standards | 329 | 844 | null |
The general equation defining admittance is given by Y = G + j B {\displaystyle Y=G+jB\,} where The admittance (Y) is the reciprocal of the impedance (Z), if the impedance is not zero: Y = 1 Z = 1 R + j X = ( 1 R + j X ) ( R − j X R − j X ) = ( R R 2 + X 2 ) + j ( − X R 2 + X 2 ) {\displaystyle Y={\frac {1}{Z}}={\frac ... | Wikipedia - Electrical susceptance - Formula | 325 | 624 | null |
{-X\;}{\;R^{2}+X^{2}}}={\frac {-X~\;}{~\;\left|Z\right|^{2}\,}}~,} where The susceptance B {\displaystyle B} is the imaginary part of the admittance Y . {\displaystyle Y~.} The magnitude of admittance is given by: | Y | = G 2 + B 2 . {\displaystyle \left|Y\right|={\sqrt {G^{2}+B^{2}\;}}~.} And similar formulas transfor... | Wikipedia - Electrical susceptance - Formula | 322 | 645 | null |
{\displaystyle Z={\frac {1}{Y}}={\frac {1}{G+jB}}=\left({\frac {G}{\;G^{2}+B^{2}}}\right)+j\left({\frac {-B\;\;}{\;G^{2}+B^{2}}}\right)~.} hence X ≡ I m { Z } = − B G 2 + B 2 = − B | Y | 2 . {\displaystyle X\equiv \operatorname {\mathcal {I_{m}}} \{\,Z\,\}={\frac {\,-B\;~}{\;G^{2}+B^{2}}}={\frac {\,-B~\;}{~\;\left|Y\... | Wikipedia - Electrical susceptance - Formula | 282 | 559 | null |
Section: Relation to capacitance. In electronic and semiconductor devices, transient or frequency-dependent current between terminals contains both conduction and displacement components. Conduction current is related to moving charge carriers (electrons, holes, ions, etc.), while displacement current is caused by time... | Wikipedia - Electrical susceptance - Relation to capacitance | 294 | 1,131 | null |
A more general definition of capacitance, encompassing electrostatic formula, is: C = I m { Y } ω = B ω , {\displaystyle C={\frac {~\operatorname {\mathcal {I_{m}}} \{\,Y\,\}~}{\omega }}={\frac {B}{~\omega ~}}~,} where Y {\displaystyle Y} is the device admittance, and B {\displaystyle B} is the susceptance, both eval... | Wikipedia - Electrical susceptance - Relation to capacitance | 206 | 728 | null |
Section: Relationship to reactance. Reactance is defined as the imaginary part of electrical impedance, and is analogous to but not generally equal to the negative reciprocal of the susceptance – that is their reciprocals are equal and opposite only in the special case where the real parts vanish (either zero resistanc... | Wikipedia - Electrical susceptance - Relationship to reactance | 165 | 715 | null |
In mathematical notation: ∀ Z ≠ 0 ⇔ Y ≠ 0 ⟹ G = 0 ⇔ R = 0 ⟺ B = − 1 X . {\displaystyle \forall ~Z\neq 0~\Leftrightarrow ~Y\neq 0\quad \Longrightarrow \quad G=0\Leftrightarrow R=0\quad \iff \quad B=-{\frac {1}{\,X\,}}~.} The minus sign is not present in the relationship between electrical resistance and the analogue of ... | Wikipedia - Electrical susceptance - Relationship to reactance | 341 | 876 | null |
{\displaystyle \forall ~Z\neq 0~\Leftrightarrow ~Y\neq 0\quad \Longrightarrow \quad G=0\Leftrightarrow R=0\quad \iff \quad B=-{\frac {1}{\,X\,}}~.} The minus sign is not present in the relationship between electrical resistance and the analogue of conductance G ≡ R e { Y } , {\displaystyle ~G\equiv \operatorname {\ma... | Wikipedia - Electrical susceptance - Relationship to reactance | 339 | 844 | null |
Article: Electrical system design. Electrical system design is the design of electrical systems. This can be as simple as a flashlight cell connected through two wires to a light bulb or as involved as the Space Shuttle. Electrical systems are groups of electrical components connected to carry out some operation. Often... | Wikipedia - Electrical system design - Summary | 150 | 788 | null |
Section: Design. The following would be appropriate for the design of a moderate to large electrical system. A specification document is written. It probably would have been written by the customer. The specification document states in plain language and numerical detail what the customer expects. If it is well written... | Wikipedia - Electrical system design - Design | 347 | 1,863 | null |
Article: Electrical wiring. Electrical wiring is an electrical installation of cabling and associated devices such as switches, distribution boards, sockets, and light fittings in a structure. Wiring is subject to safety standards for design and installation. Allowable wire and cable types and sizes are specified accor... | Wikipedia - Electrical wiring - Summary | 160 | 962 | null |
Section: Wiring methods. Materials for wiring interior electrical systems in buildings vary depending on: Intended use and amount of power demand on the circuit Type of occupancy and size of the building National and local regulations Environment in which the wiring must operate. Wiring systems in a single family home ... | Wikipedia - Electrical wiring - Wiring methods | 295 | 1,602 | null |
Section: Cables > Modern wiring materials. Modern non-metallic sheathed cables, such as (US and Canadian) Types NMB and NMC, consist of two to four wires covered with thermoplastic insulation, plus a wire for Protective Earthing/Grounding (bonding), surrounded by a flexible plastic jacket. In North America and the UK t... | Wikipedia - Electrical wiring - Cables > Modern wiring materials | 325 | 1,735 | null |
Generally, single conductor building wire in small sizes is solid wire, since the wiring is not required to be very flexible. Building wire conductors larger than 10 AWG (or about 5 mm2) are stranded for flexibility during installation, but are not sufficiently pliable to use as appliance cord. Cables for industrial, c... | Wikipedia - Electrical wiring - Cables > Modern wiring materials | 322 | 1,681 | null |
The environment of the installed wires determine how much current a cable is permitted to carry. Because multiple conductors bundled in a cable cannot dissipate heat as easily as single insulated conductors, those circuits are always rated at a lower ampacity. Tables in electrical safety codes give the maximum allowabl... | Wikipedia - Electrical wiring - Cables > Modern wiring materials | 350 | 1,895 | null |
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