1.1.2 Development of Live Working and History of T...
1.Live Working of Lines in the United States
The first country in the world to carry out live working is the United States.In 1913,the first live working was carried out in Ohio.At that time,the ground potential method was adopted,and tools for live working were made of wood.Dry wooden rod,due to its good insulation performance,could fully withstand the phase-to-ground voltage.Although tools made at that time were rough and cumbersome,they were the pioneer of live working after all.With the continuous increase of voltage level,it was necessary to have a live operating bar with stronger insulation performance to meet the requirements.The plastic sheathed wooden pole was first introduced and applied in live working by Chance Company in the United States,and then came the reinforced synthetic resin pipe mixed with glass fiber which had the characteristics of high voltage-withstand strength and uniform electric field distribution.Soon afterwards,it was widely used in live working of transmission line.At present,various power companies in the United States have been engaged in live working overhaul and maintenance projects for transmission lines,and many power companies have also carried out live line patrol and live maintenance projects with helicopters.Fig.1-13 is the equipotential operation with helicopter carried out in the United States.
Fig.1-13 Equipotential Operation with Helicopter Carried out in the United States
2.Live Working of Lines in Japan
In Japan,live working on transmission lines is relatively few,and the proportion of live working on distribution lines is large.At the same time,Japan puts forward higher requirements for the reliability of power supply of distribution network,which require to gradually realize complete non-interruption operation.Compared with the past,Japan's live working has gradually moved towards automation,intelligentization and mechanization.It is the first country in the world to carry out research and application of live working robots.In the early 1990s,four Japanese electric power companies developed live working robots with hydraulic mechanical arms and used them in the maintenance of distribution network system.In order to improve the reliability of power supply and support the overall popularization of non-interruption operation,Japan had developed a series of mechanized operation tools and equipment which were continuously promoted and applied,including tools and supporting facilities needed for direct or indirect live working such as high-voltage generator locomotive,live washing transformer trolley,low-voltage non-interruption switching device,and accident point detection vehicle used in emergency accidents.The use of these mechanized tools and instruments for live working reduces labor intensity and improves work efficiency to a certain extent;Fig.1-14 is the live working carried out by robots in Japan.
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Fig.1-14 Live Working Carried out by Robots in Japan
3.Live Working of Lines in Russia
In the 1930s,Russia(Soviet Union)began to carry out live working of transmission lines.In the 1940s,the new method of equipotential operation was applied and popularized on a large scale;in the mid-1950s,live working had been used in most of line emergency repair work.
A complete and reasonable operation method has been developed for live working of 330-750kV transmission line in Russia.Considering the reliability of operation,transmission line is equipped with tools and instruments for live working suitable for high voltage and intense electric field operation.Its live working mainly includes insulation test,insulator string replacement,conductor repair,anti-corrosion paint coating of overhead line and live equipment,etc.,which are in the forefront of the world in live working.In addition,Russia is also actively engaged in research on live working technology of 1150kV line and has in-depth research on safety protection of live working of 1150kVAC transmission line.
4.Live Working of Lines in Britain and France
In the middle of the 20th century,Britain began to use operating poles for live working,typically those for measuring voltage distribution of insulator string,etc.The research on live working of transmission line began till 1965.At that time,France also set up technical committees and experimental research institutes for live working that mainly researched principles of live working,safety regulations of live working,equipotential working methods,indirect working methods with tools,etc.;its operation items included live replacement of insulator strings,replacement of cross arms,replacement of anti-vibration devices.80%of work on UHV transmission line is done by equipotential operation method,and work on lines with voltage level above 400kV is jointly done by indirect operation method and equipotential operation method with insulating tools.At present,live working in Britain and France is mainly used on distribution line,while that on transmission line is relatively few.This is mainly because transmission line has many backup devices,and Britain and France do not need to build large trans-regional transmission network due to geographical area and energy distribution.