General Requirements to Construction of Substation
Substations are a vital element in a power supply system of industrial enterpris．They rve to receive ，convert and distribute electric energy .Depending on power and purpo ,the substations 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 energy received from the power source is transformed from 110-220kV usually to 6-10kV(sometimes 35kV) which is distributed among substations of the enterpri and is fed to high-voltage rvices.
Central distribution substations receive energy from power systems and distribute it (without or with partial transformation) via aerial and cable lines of deep entrances at a voltage of 110-220kV over the enterpri 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 simplified switching circuits at primary voltage; it is fed fr
om the power to an individual object or region .Low-and medium-power shop substations transform energy from 6-10kV to a condary voltage of 380/220 or 660/380.
Step-up transformer substations are ud at power plants for transformation of energy produced by the generators to a higher voltage which decreas loss 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 miconductor rectifiers are convert energy of one frequency to another .Converter substations with miconductor 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 functions 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 sub
征路stations of the aerial type .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 u of large blocks and asmblies prepared at the site shops of electric engineering organizations and factories of electrical engineering industry .Substations are usually designed for operation without continuous attendance of the duty personnel but with the u of elementary automatic and signaling devices.
公鸡怎么画When constructing the structural part of a substation .it is advisable to u light-weight industrial structures and elements (panels ,floors ,etc.) made of bent ctions .The elements are pre-made outside the erection zone and are only asmbled at site .This considerably cuts the terms and cost of construction.
Basic circuitry concepts of substations are chon when designing a powersupply system of the enterpri .Substations feature primary voltage entrances .transformers and output cable lines or current conductors of condary voltage .Substations are mounted from eq
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uipment and elements described below .The number of possible combinations of equipment and elements is very great .Whenelaborating 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 rerve facility which allows rapid and faultless redundancy of individual elements and using equipment.
When designing transformer substations of industrial enterpris 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 reliable and economic power supply;
史记小故事2. Wide u of unitized constructions and busless substations;
3.Substantiated employment of automatics and telemetry ;if the substation design does not envisage the u of automatics or telemetry ,the circuitry is so arranged as to allow for adding such equipment in future without excessive investments and re-work.
4.U of simple and cheap devices-isolating switches ,short-circuiting switches ,load-breaking isolators ,fus ,with due regard for their switching capacity may drastically cut the need for expensive and critical oil ,vacuum ,solenoid and air switches .Substation and switch-gear circuitries are so made that using the equipment of each production line is fed from individual transformers ,asmblies ,the lines to allow their disconnection simultaneously with mechanisms without disrupting operation of adjacent production flows.
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When elaborating circuitry of a substation, the most vital task is to properly choo and arrange switching devices(switches ,isolators ,current limiters ,arresters ,high-voltage fus).The decision depends on the purpo ,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反射式望远镜 to parate 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 tho particles than there are drops of water in the Atlantic O照片墙布置图片纯种萨摩耶cean.
