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Transformerboard
Electrical insulation papers are specific types of paper that are used as electrical insulation. They are used in many applications due to the outstanding electrical properties of pure cellulose. Cellulose is a good insulator and is also polar, having a relative permittivity significantly greater than 1. Electrical paper products are classified by their thickness, with tissue considered papers less than 1.5 mils (0.0381 mm) thickness, and ''board'' considered more than 20 mils (0.508 mm) thickness.ASTM ''Paper and paperboard: characteristics, nomenclature, and significance of tests'', ASTM, 1951 page 26 History The use of paper board as electrical insulation paper started in the early-mid 20th century. Since the need for high voltage electrical transformers, there has been a need for an insulating material that could withstand the high electrical and physical stresses experienced around a core and windings. Pressboard, a board made by compressing layers of paper togeth ...
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Twisted Pair
Twisted pair cabling is a type of communications cable in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted balanced pair, a twisted pair reduces electromagnetic radiation from the pair and crosstalk between neighboring pairs and improves rejection of external electromagnetic interference. It was invented by Alexander Graham Bell. For additional noise immunity, twisted-pair cabling may be shielded. Cable with shielding is known as shielded twisted pair (STP) and without as unshielded twisted pair (UTP). Explanation A twisted pair can be used as a balanced line, which as part of a balanced circuit can greatly reduce the effect of noise currents induced on the line by coupling of electric or magnetic fields. The idea is that the currents induced in each of the two wires are very nearly equal. The twisting ensures that the two wires are on average the ...
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Insulation System
The electrical insulation system for wires used in Electric generator, generators, electric motors, transformers, and other wire-wound electrical components is divided into different classes by temperature and temperature rise. The electrical insulation system is sometimes referred to as ''insulation class'' or ''thermal classification''. The different classes are defined by NEMA, Underwriters Laboratories (UL), and International Electrotechnical Commission, IEC standards. For complete electrically operated appliances, the "insulation system" is the overall design of electrical insulation of the energized components to ensure correct function of the device and protection of the user from electric shock. Temperature classes The maximum hot-spot operating temperature is reached by adding the rated ambient temperature of the machine (often 40 °C), a temperature rise, and a 10 °C hot-spot allowance. Electrical machines are usually designed with an average temperature belo ...
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Vulcanized Fibre
Vulcanized fibre, also known as red fibre, is a laminated plastic composed of only cellulose. This material is a tough, resilient, hornlike material that is lighter than aluminium, tougher than leather, and stiffer than most thermoplastics. The newer wood-laminating grade of vulcanized fibre is used to strengthen wood laminations used in skis, skateboards, support beams and as a sub-laminate under thin wood veneers. A product very similar to vulcanized fibre is leatheroid; however, Leatheroid is made using a different chemical process. Since 2004, the scientific community has regained interest in this material due to its renewability and excellent physical properties, giving birth to the field of all-cellulose composites. These composites are all made of a matrix consisting of dissolved or partially dissolved cellulose, and the reinforcement remains cellulose fibres. A variety of solvents other than zinc chloride has been explored, including sodium hydroxide at low temperatures a ...
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Calender
A calender is a series of hard pressure rollers used to finish a sheet of material such as paper, textiles, rubber, or plastics. Calender rolls are also used to form some types of plastic films and to apply coatings. Some calender rolls are heated or cooled as needed. Calenders are sometimes misspelled ''calendars''. Etymology The word "calender" itself is a derivation of the word κύλινδρος ''kylindros'', the Greek word that is also the source of the word "cylinder". History Calender mills for pressing Serge (fabric), serge were apparently introduced to the Netherlands by Flemish refugees from the Eighty Years' War in the 16th and 17th centuries. In eighteenth century China, workers called "calenderers" in the silk- and cotton-cloth trades used heavy rollers to press and finish cloth. In 1836, Edwin M. Chaffee, of the Roxbury India Rubber Company, patented a four-roll calender to make rubber sheet. Chaffee worked with Charles Goodyear with the intention to "produ ...
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Tissue Paper
Tissue paper, or simply tissue, is a lightweight paper or light crêpe paper. Tissue can be made from recycled pulp (paper), paper pulp on a paper machine. Tissue paper is very versatile, and different kinds are made to best serve these purposes, which are hygienic tissue paper, facial tissues, paper towels, as packing material, among other (sometimes creative) uses. The use of tissue paper is common in developed nations, around 21 million tonnes in North America and 6 million in Europe, and is growing due to urbanization. As a result, the industry has often been scrutinized for deforestation. However, more companies are presently using more recycled fibres in tissue paper. Properties The key properties of tissues are absorbency, basis weight, thickness, bulk (specific volume), brightness, stretch, appearance and comfort. Production Tissue paper is produced on a Fourdrinier machine, paper machine that has a single large steam heated drying cylinder (Yankee dryer) fitted with ...
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Capacitor
In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term still encountered in a few compound names, such as the '' condenser microphone''. It is a passive electronic component with two terminals. The utility of a capacitor depends on its capacitance. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed specifically to add capacitance to some part of the circuit. The physical form and construction of practical capacitors vary widely and many types of capacitor are in common use. Most capacitors contain at least two electrical conductors, often in the form of metallic plates or surfaces separated by a dielectric medium. A conductor may be a foil, thin film, sintered bead of metal, or an electrolyte. The nonconductin ...
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Submarine Power Cable
A submarine power cable is a transmission cable for carrying electric power below the surface of the water.Underwater Cable an Alternative to Electrical Towers
Matthew L. Wald, '''', 2010-03-16, accessed 2010-03-18.
These are called "submarine" because they usually carry electric power beneath salt water (arms of the , s,
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Plastic
Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding, molded, Extrusion, extruded, or Compression molding, pressed into a diverse range of solid forms. This adaptability, combined with a wide range of other properties such as low weight, durability, flexibility, chemical resistance, low toxicity, and low-cost production, has led to their widespread use around the world. While most plastics are produced from natural gas and petroleum, a growing minority are produced from renewable resources like polylactic acid. Between 1950 and 2017, 9.2 billion metric tons of plastic are estimated to have been made, with more than half of this amount being produced since 2004. In 2023 alone, preliminary figures indicate that over 400 million metric tons of plastic were produced worldwide. If global trends ...
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Paper Density
Paper density is a paper product's mass per unit volume. The density can be calculated by dividing the grammage of paper (in grams per square metre or "gsm") by its caliper (usually in micrometres, occasionally in mils). The "ISO 534:2011, Paper and board — Determination of thickness, density and specific volume" indicates that the paper density is expressed in grams per cubic centimeter (g/cm3). See also * Grammage * Density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ... ** Area density ** Linear density * References External links Understanding Paper Weights( Staples, Inc.) M-weight CalculatorPaper Weight Calculator Paper Printing {{material-stub ...
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Electric Current
An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge carriers, which may be one of several types of particles, depending on the Electrical conductor, conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or Electron hole, holes. In an Electrolyte#Electrochemistry, electrolyte the charge carriers are ions, while in Plasma (physics), plasma, an Ionization, ionized gas, they are ions and electrons. In the International System of Units (SI), electric current is expressed in Unit of measurement, units of ampere (sometimes called an "amp", symbol A), which is equivalent to one coulomb per second. The ampere is an SI base unit and electric current is a ISQ base quantity, base quantity in the International System of Qua ...
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