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1、精选优质文档-倾情为你奉上精选优质文档-倾情为你奉上专心-专注-专业专心-专注-专业精选优质文档-倾情为你奉上专心-专注-专业General Requirements to Construction of SubstationSubstations are a vital element in a power supply system of industrial enterprisesThey serve to receive ,convert and distribute electric energy .Depending on power and purpose ,the substa
2、tions are divided into central distribution substations for a voltage of 110-500kV;main step-down substations for110-220/6-10-35kV;deep entrance substations for 110-330/6-10Kv;distribution substations for 6-10Kv;shop transformer substations for 6-10/0.38-0.66kV.At the main step-down substations, the
3、 energy received from the power source is transformed from 110-220kV usually to 6-10kV(sometimes 35kV) which is distributed among substations of the enterprise and is fed to high-voltage services.Central distribution substations receive energy from power systems and distribute it (without or with pa
4、rtial transformation) via aerial and cable lines of deep entrances at a voltage of 110-220kV over the enterprise territory .Central distribution substation differs from the main distribution substation in a higher power and in that bulk of its power is at a voltage of 110-220kV;it features simplifie
5、d switching circuits at primary voltage; it is fed from the power to an individual object or region .Low-and medium-power shop substations transform energy from 6-10kV to a secondary voltage of 380/220 or 660/380.Step-up transformer substations are used at power plants for transformation of energy p
6、roduced by the generators to a higher voltage which decreases losses at a long-distance transmission .Converter substations are intended to convert AC to DC (sometimes vice versa) and to convert energy of one frequency to another .Converter substations with semiconductor rectifiers are convert energ
7、y of one frequency to another .Converter substations with semiconductor rectifiers are most economic. Distribution substations for 6-10kV are fed primarily from main distribution substations (sometimes from central distribution substations).With a system of dividing substations for 110-220kV, the fu
8、nctions of a switch-gear are accomplished by switch-gears for 6-10kV at deep entrance substations.Depending on location of substations their switch-gear may be outdoor or indoor. The feed and output lines at 6-10kV substations are mainly of the cable type .at 35-220kV substations of the aerial type
9、.When erecting and wiring the substations ,major attention is given to reliable and economic power supply of a given production.Substations are erected by industrial methods with the use of large blocks and assemblies prepared at the site shops of electric engineering organizations and factories of
10、electrical engineering industry .Substations are usually designed for operation without continuous attendance of the duty personnel but with the use of elementary automatic and signaling devices.When constructing the structural part of a substation .it is advisable to use light-weight industrial str
11、uctures and elements (panels ,floors ,etc.) made of bent sections .These elements are pre-made outside the erection zone and are only assembled at site .This considerably cuts the terms and cost of construction.Basic circuitry concepts of substations are chosen when designing a powersupply system of
12、 the enterprise .Substations feature primary voltage entrances .transformers and output cable lines or current conductors of secondary voltage .Substations are mounted from equipment and elements described below .The number of possible combinations of equipment and elements is very great .Whenelabor
13、ating a substation circuitry ,it is necessary to strive for maximum simplification and minimizing the number of switching devices .Such substations are more reliable and economic .Circuitry is simplified by using automatic reclosure or automatic change over to reserve facility which allows rapid and
14、 faultless redundancy of individual elements and using equipment.When designing transformer substations of industrial enterprises for all voltages , the following basic considerations are taken into account:1. Preferable employment of a single-bus system with using two-bus systems only to ensure a r
15、eliable and economic power supply;2. Wide use of unitized constructions and busless substations;3.Substantiated employment of automatics and telemetry ;if the substation design does not envisage the use of automatics or telemetry ,the circuitry is so arranged as to allow for adding such equipment in
16、 future without excessive investments and re-work.4.Use of simple and cheap devices-isolating switches ,short-circuiting switches ,load-breaking isolators ,fuses ,with due regard for their switching capacity may drastically cut the need for expensive and critical oil ,vacuum ,solenoid and air switch
17、es .Substation and switch-gear 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 ci
18、rcuitry of a substation, the most vital task is to properly choose and arrange switching devices(switches ,isolators ,current limiters ,arresters ,high-voltage fuses).The decision depends on the purpose ,power and significance of the substation.Many years ago, scientists had very vague ideas about e
19、lectricity. 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 particl
20、es 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 weig
21、hs 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
22、 and move through a wire,we describe this action by saying that electricity is flowing through the wire.Yes,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 thes
23、e 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
24、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 8.The third orbit is packed with 18 electrons . And the outside orbit has only one electron.It is this outside electron that the copper ato
25、m is continually losing, for it is not very closely tied to the atom. It wanders off, is replaced by another free-roving electron, and then this second electron also wanders away. Consequently,in a copper wire free electrons are floating around in all directions among the copper atoms.Thus, even thr
26、ough the copper wire looks quite motionless to your ordinary eye, there is a great deal of activity going on inside it. If the wire were carrying electricity to an electric light or to some other electrical device, the electrons would not be moving around at random. Instead, many of them would be ru
27、shing in the same direction-from one end of the wire to the other.This brings us to the second question .How can free electrons be made to move along a wire? Well ,men have found several ways to do that .One way is chemical. Volta,s voltaic pile,or battery, is a chemical device that makes electricit
28、y(or electrons)flow in wires. Another way is magnetic. Faraday and Henry discovered how magnets could be used to make electricity flow in a wire.Magnets Almost everyone has seen horseshoe magnets-so called because they are shaped like horseshoes. Probably you have experimented with a magnet, and not
29、iced how it will pick up tacks and nails, or other small iron objects. Men have known about magnets for thousands of years. Several thousand years ago, according to legend, a shepherd named Magnes lived on the island of Crete, in the Mediterranean Sea .He had a shepherds crook tipped with iron. One
30、day he found an oddly shaped black stone that stuck to this iron tip.Later, when many other such stones were found, they were called magnets(after Magnets).These were natural magnets. In recent times men have learned how to make magnets out of iron. More important still, they have discovered how to
31、use magnets to push electrons through wires-that is, how to make electricity flow. Before we discuss this, there arecertain characteristics of magnets that we should know about.If a piece of glass is laid on top of a horse- shoes magnet, and if iron filings are then sprink ledon the glass, the filin
32、gs will arrange themselves into lines. If this same thing is trid with a bar magnet(a horseshoe magnet straightened out),the lines can be seen more easily. These experiments demonstrate what scientists call magnetic lines of force. Magnets, they explain, work through lines of force that ext- end bet
33、ween the two ends of the magnet. But electrons seem to have magnetic lines of force around them, too.This can be proved by sticking a wire through a piece ofcard board, sprinkling iron filings on the cardboard, and connecting a battery to the wire. The filings will tend to form rings around the wire
34、,as a result of the magnetism of the moving electrons(or electricity).So we can see that there is arelationship between moving electrons and magnetism, Magnetism results from the movement of electrons. Of course, electrons are not really flowing in the bar magnet, but they are in motion, circling th
35、e nuclei of the iron atoms. However, in the magnet, circling thelined up in such a way that their electrons are circling in the same direction. Perhaps a good comparison might be a great number of boys whirling balls onstrings in a clockwise direction around their heads.变电站建设的一般要求变电站(所)在电源系统的工业企业是一个
36、至关重要的因素。他们接收,转换和发送电能。根据能源和需求,变电站分为中央配电变电站电压为110-500kV;主要降压变电所电压为110-220/6-10-35kV; 深入口变电站为110-330/6-10kV;二次变电站的电压为6-10Kv;车间变电所电压为6-10/0.38-0.66kV。在主要的降压变电所,电源能量转化电压为110-220kV,通常使用6-10Kv(有时为35kV变电所)的电压分配给企业和被用来满足高压服务。中央配电变电站从电力系统接收能量并分发它(不包括或者包括部分变换) 给企业不同区域,通过空中电缆和地下电缆线路电压为110-220kV。 中央分配变电站站不同于主配电变
37、电它是一个更强大的电力设施,它的电压大部分在110-220kV的电压。它可以简化初级电压、中级电压或地区的开关电路。中低级别变电站改造能量来自6-10kv的电压,它的二次侧电压为380/220或660/380。升压变压器变电站用于将电厂产生的能量转化使发电机产生的电压升高,从而有效地减少在远距离输电能量的损失转换器变电站的目的是为了将直流转换成交流(有时相反)和转换成能量时改变频率。转换器变电站的能量转换是用半导体整流器来变频的。带半导体整流器的转化器变电站是最经济的。6-10kV的配电变电站主要依据主配电变电站(有时依据中央配电变电站)。110-220kV变电站系统区域的划分时,根据变电站设
38、备功能划分时是有学问的,6-10kV的变电站设备划分在变电站的入口。根据变电站变的位置,电站设备在可以露天或室内。6-10kV变电站的在电缆的类型主要是供给输出线。在35-220kV变电站空中线路样式,在变电站架线和接线,主要注重供电生产的可靠和经济。用工业的方式建设变电站,是使用大量的数块和在电气工程组织和工厂电气工程等行业的车间的位置进行组装。变电站通常是专为不连续操作的责任人员所设计,但用的是基本的自动设备和信号装置。当建立变电站结构的一部分,应当采用薄型建造结构以及由弯段组成的组件(板材、地板等)。这些元件是预先安装区外面建造区域并且只是在这个位置组装。这样可以有效的削减变电所建造成本
39、。变电站基本电路概念设计的选择,是根据企业的供电系统特点得到的。变电站电压特性主要入口,变压器和输出电缆线路导线或当前导体的二次电压.变电站安装的设备和元件,设备和元件的若干种可能的组合是非常好的。当阐述了变电站的电路时争取切换装置最大的简化和数目的最小化。这样的变电站更可靠、经济。电路简化是采用自动接入或自动转入储备的方法,允许快速和无错误的自动接入每一个元件和使用设备。当设计工业企业全电压变电站时,下面的基本因素都要考虑在内。1.优先使用采用两编组的单总线系统可以确保可靠的和经济的供应电力。2.配套建设和变电站广泛使用。3.变电站使用自动化并且支持遥测技术;如果变电站的设计并不支持使用自动
40、化或遥测、线路安而且不允许添加设备,确保以后没有过度投资和返工。4.使用简单、便宜的装置,有绝缘装置的断路器、短路开关、过载保护隔离器、保险丝,预期到他们的交换容量可考虑大幅度削减昂贵的器件需要和临界油、真空、螺线管和空气开关电路使用。变电站和开关电路,采用这样的设备的每个生产线服从个体变压器、装配、允许他们同时的断开而不破坏断开连接的生产流程的机制的线条。变电站的线路的意义,最重要的一点是要妥善安排与选择转换器件(开关、隔离者、电流限制器等、避雷器、高低压熔断器),这决定了变电站的目的、功能和意义。很多年以前,科学家们对电仍只有很模糊的概念。他们之中不少人认为电是一种“流体”,这种流体就像水流经管道一样流过导线。但他们并不了解是什么东西使电流动。他们之中的许多人觉得电是有某种极小的微粒构成的,但试图把电分离成单个的小颗粒他们却束手无策。此后,以为伟大的美国科学家密利坎于1909年,真正地称出了单个的电粒子的重量并算出它的电荷而使科学界震惊不已。这可能是人类做过的最细致的
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