高壓變電站電氣一次系統(tǒng)畢業(yè)設(shè)計外文翻譯-電氣類-wenkub
2023-05-18 14:14:36 本頁面
【正文】 so arranged as to allow for adding such equipment in future without excessive investments and rework. of simple and cheap devicesisolating switches ,shortcircuiting switches ,loadbreaking isolators ,fuses ,with due regard for their switching capacity may drastically cut the need for expensive and critical oil ,vacuum ,solenoid and air switches .Substation and switchgear circuitries are so made that using the equipment of each production line is fed from individual transformers ,assemblies ,the lines to allow their disconnection simultaneously with mechanisms without disrupting operation of adjacent production flows. When elaborating circuitry of a substation, the most vital task is to properly 6 choose and arrange switching devices(switches ,isolators ,current limiters ,arresters ,highvoltage fuses).The decision depends on the purpose ,power and significance of the substation. Many years ago, scientists had very vague ideas about electricity. Many of them thought of it as a sort of fluid that flowed through wires as water flows through pipes, but they could not understand what made it flow. Many of them felt that electricity was made up of tiny particles of some kind ,but trying to separate electricity into individual particles baffled them. Then, the great American scientist Millikan, in 1909,astounded the scientific world by actually weighing a single particle of electricity and calculating its electric charge. This was probably one of the most delicate weighing jobs ever done by man,for a single electric particle weighs only about half of a millionth of a pound. To make up a pound it would take more of those particles than there are drops of water in the Atlantic Ocean. They are no strangers to us, these electric particles, for we know them as electrons. When large numbers of electrons break away from their atoms and move through a wire,we describe this action by saying that electricity is flowing through the ,the electrical fluid that early scientists talked about is nothing more than electrical flowing along a wire. But how can individual electrons be made to break away from atoms? And how can these free electrons be made to along a wire? The answer to the first question lies in the structure of the atoms themselves. Some atoms are so constructed that they lose electrons easily. An atom of copper, for example ,is continually losing an electron, regaining it(or another electron),and losing it again. A copper atom normally has 29 electrons, arranged in four different orbits about its nucleus. The inside orbit has 2 electrons. The next larger orbit has third orbit is packed with 18 electrons . And the outside orbit has only one is this outside electron that the copper atom is continually losing, for it is not very closely tied to the at
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