Principle and Structure of High Voltage Transmission Line
Date: 2013-04-01 10:56:47 Views: 1558
A method which may boost and transmit output voltage of generator by transformer in power plant is called high voltage transmission. This kind of transmission method is applied because that under the same transmission power, the higher the voltage is, the smaller the current is. Therefore high voltage transmission may reduce current in power transmission and then decrease heat loss caused by current and reduce material cost of long distance power transmission.
Major components of overhead transmission line are: lead wire and lightning wire (overhead earth wire), tower, insulator, armour clamp, tower foundation, stay wire and grounding device etc.
Item
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Feature & Function
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Straight Line Tower
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It’s used on straight-line segment of transmission line between strain towers. It mainly withstands vertical load and transverse load of line, as well as a certain longitudinal force.
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Angle Tower
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It’s used at little corner of line. Corner is normally no more than 20°. Lead wire is supported by suspension type insulator chain. Insulator chain has deflection angle. It’s used to extend strain section length and reduce construction cost.
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Strain Tower
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It’s used at line corner or place with special request. It may withstand large transverse load and longitudinal load. It has the effect of strengthening line longitudinal strength and limiting line accident range. It may also be used as tension stringing tower in installation and reconditioning.
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Transposition Tower
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It’s used at parts of line, at which lead wire phase shall be changed. It has two types as linear type and tension type.
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Large Span Tower
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It’s used at places, at which line striding across river, lake or strait. When the across span is large (normally above 1000M) or tower is high, selection of wire and design of tower shall be specially considered to form a separate strain section. Large span tower has complex structure. It has large steel consumption and high amount of investment. And currently composite construction tower, steel tube tower or concrete-cylinder-steel-cross-arm compounded tower are mostly applied inland.
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Terminal Tower
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Terminal tower is normally applied as the first outlet base tower of power plant or substation. The characteristic of this kind of terminal tower is that it shall withstand big relay difference of lead wire and earth wire.
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