|
Shared Neutral
In electrical engineering, ground (or earth) and neutral are circuit conductors used in alternating current (AC) electrical systems. The neutral conductor carries alternating current (in tandem with one or more ''phase '' conductors) during normal operation of the circuit. By contrast, a ground conductor is not intended to carry current for normal operation, but instead connects exposed conductive parts (such as equipment enclosures or conduits enclosing wiring) to Earth (the ground), and only carries significant current in the event of a circuit fault that would otherwise energize exposed conductive parts and present a shock hazard. In such case the intention is for the fault current to be large enough to trigger a circuit protective device that will either de-energize the circuit, or provide a warning. To limit the effects of leakage current from higher-voltage systems, the neutral conductor is often connected to earth ground at the point of supply. Significant voltage unin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta-wye Transformer
A delta-wye transformer is a type of three-phase electric power transformer design that employs delta-connected windings on its primary and wye/star connected windings on its secondary. A neutral wire can be provided on wye output side. It can be a single three-phase transformer, or built from three independent single-phase units. An equivalent term is delta-star transformer. Transformers Delta-wye transformers are common in commercial, industrial, and high-density residential locations, to supply three-phase Electric power distribution, distribution systems. An example would be a distribution transformer with a delta primary, running on three 11 kV phases with no neutral or earth required, and a star (or wye) secondary providing a 3-phase supply at 415 V, with the domestic voltage of 240 available between each phase and the earthed (grounded) neutral point. The delta winding allows third-harmonic currents to circulate within the transformer, and prevents third-harmonic cur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harmonics (electrical Power)
In an electric power system, a harmonic of a voltage or current waveform is a sinusoidal wave whose frequency is an integer multiple of the fundamental frequency. Harmonic frequencies are produced by the action of non-linear loads such as rectifiers, discharge lighting, or saturated electric machines. They are a frequent cause of power quality problems and can result in increased equipment and conductor heating, misfiring in variable speed drives, and torque pulsations in motors and generators. Harmonics are usually classified by two different criteria: the type of signal (voltage or current), and the order of the harmonic (even, odd, triplen, or non-triplen odd); in a three-phase system, they can be further classified according to their phase sequence ( positive, negative, zero). The measurement of the level of harmonics is covered by the IEC 61000-4-7 standard. Current harmonics In a normal alternating current power system, the current varies sinusoidally at a specific f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Electrical Code
The National Electrical Code (NEC), or NFPA 70, is a regionally adoptable standard for the safe installation of electrical wiring and equipment in the United States. It is part of the National Fire Code series published by the National Fire Protection Association (NFPA), a private trade association. Despite the use of the term "national," it is not a federal law. It is typically adopted by states and municipalities in an effort to standardize their enforcement of safe electrical practices. In some cases, the NEC is amended, altered and may even be rejected in lieu of regional regulations as voted on by local governing bodies. The "authority having jurisdiction" inspects for compliance with the standards. The NEC should not be confused with the National Electrical Safety Code (NESC), published by the Institute of Electrical and Electronics Engineers (IEEE). The NESC is used for electric power and communication utility systems including overhead lines, underground lines, and pow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks in World War II, Tanks and Air warfare of World War II, aircraft played major roles, enabling the strategic bombing of cities and delivery of the Atomic bombings of Hiroshima and Nagasaki, first and only nuclear weapons ever used in war. World War II is the List of wars by death toll, deadliest conflict in history, causing World War II casualties, the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Allied-occupied Germany, Germany, Allied-occupied Austria, Austria, Occupation of Japan, Japan, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper Wire And Cable
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor. Copper is the electrical conductor in many categories of electrical wiring.Pops, Horace, 2008, Processing of wire from antiquity to the future, Wire Journal International, June, pp 58-66 Copper wire is used in power generation, power transmission, power distribution, telecommunications, electronics circuitry, and countless types of electrical equipment. Copper and its alloys are also used to make electrical contacts. Electrical wiring in buildings is the most important market for the copper industry. Roughly half of all copper mined is used to manufacture electrical wire and cable conductors. Properties of copper Electrical conductivity Electrical conductivity is a measure of how well a material transports an electric charge. This is an essential propert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clothes Dryer
A clothes dryer (tumble dryer, drying machine, drying device, or simply dryer) is a powered Home appliance, household appliance that is used to remove moisture from a load of clothing, bedding and other textiles, usually after they are washed in the washing machine. Many dryers consist of a rotating drum called a "tumbler" through which heated air is circulated to evaporate moisture while the tumbler is rotated to maintain air space between the articles. Using such a machine may cause clothes to Shrinkage (fabric), shrink or become less soft (due to loss of short soft fibers). A simpler non-rotating machine called a "drying cabinet" may be used for delicate fabrics and other items not suitable for a tumble dryer. Other machines include steam to de-shrink clothes and avoid ironing. Tumble dryers Tumble dryers continuously draw in the Ambient air quality criteria, ambient air around them and heat it before passing it through the tumbler. The resulting hot, humid air is usually vent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cook Top
A cooktop (American English), stovetop (Canadian and American English) or hob (British English), is a device commonly used for cooking that is commonly found in kitchens and used to apply heat to the base of pans or pots. Cooktops are often found integrated with an oven into a kitchen stove but may also be standalone devices. Cooktops are commonly powered by gas or electricity, although oil or other fuels are sometimes used. Gas Gas cooktops consist of one or more gas burners with arrangements to control the rate of flow. They often have integral lighters or (in older models) pilot lights, and may have safety interlocks designed to reduce the risk of hazardous gas leaks. Gas cooking has been associated with negative health effects, such as reduced pulmonary function and a higher rate of respiratory symptoms in children. Electric Coil An electric coil cooktop uses electric elements that directly heat pots placed on them. They are inexpensive to buy and maintain, but are cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kitchen Stove
A kitchen stove, often called simply a stove or a cooker, is a kitchen appliance designed for the purpose of cooking food. Kitchen stoves rely on the application of Heat transfer#Conduction, direct heat for the cooking process and may also contain an oven, used for baking. "Cookstoves" (also called "cooking stoves" or "wood stoves") are heated by burning wood or charcoal; "gas stoves" are heated by gas; and "electric stoves" by electricity. A stove with a built-in cooktop is also called a range. In the industrialized world, as stoves replaced open fires and braziers as a source of more efficient and reliable heating, models were developed that could also be used for cooking, and these came to be known as ''kitchen stoves''.Montagne, Prosper ''New Larousse Gastronomique'' Hamlin Publishing Group 1977 268,901 Quoting Eugène Viollet-le-Duc on cooking in the Middle Ages: "The division of stoves into several compartments as in our day was seldom seen. The dishes were cooked on the fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equipotential
In mathematics and physics, an equipotential or isopotential refers to a region (mathematics), region in space where every point is at the same Electric potential, potential. This usually refers to a scalar potential (in that case it is a level set of the potential), although it can also be applied to vector potentials. An equipotential of a scalar potential function (mathematics), function in -dimensional space is typically an ()-dimensional space. The del, del operator illustrates the relationship between a vector field and its associated scalar potential field. An equipotential region might be referred as being 'of equipotential' or simply be called 'an equipotential'. An equipotential region of a scalar potential in three-dimensional space is often an equipotential surface (or ''potential isosurface''), but it can also be a three-dimensional solid (mathematics), mathematical solid in space. The gradient of the scalar potential (and hence also its opposite, as in the case of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tram
A tram (also known as a streetcar or trolley in Canada and the United States) is an urban rail transit in which Rolling stock, vehicles, whether individual railcars or multiple-unit trains, run on tramway tracks on urban public streets; some include segments on segregated Right-of-way (property access), right-of-way. The tramlines or tram networks operated as public transport are called tramways or simply trams/streetcars. Because of their close similarities, trams are commonly included in the wider term ''light rail'', which also includes systems separated from other traffic. Tram vehicles are usually lighter and shorter than Main line (railway), main line and rapid transit trains. Most trams use electrical power, usually fed by a Pantograph (transport), pantograph sliding on an overhead line; older systems may use a trolley pole or a bow collector. In some cases, a contact shoe on a third rail is used. If necessary, they may have dual power systems—electricity in city stre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Railway Electrification System
Railway electrification is the use of electric power for the propulsion of rail transport. Electric railways use either electric locomotives (hauling passengers or freight in separate cars), electric multiple units ( passenger cars with their own motors) or both. Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines, but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches, and transformers. Power is supplied to moving trains with a (nearly) continuous conductor running along the track that usually takes one of two forms: an overhead line, suspended from poles or towers along the track or from structure or tunnel ceilings and contacted by a pantograph, or a third rail mounted at track level and contacted by a sliding " pickup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
