Live working mode and safety protection of the hot

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Live working mode and safety protection of distribution lines

6 ~ 10kV distribution network is a power infrastructure directly facing users. From the 1960s to the early 1980s, live line operation of power distribution was promoted in China, but due to many problems in operation mode, safety protection equipment, operation steps and backup safety protection, this operation was stopped in some areas. At present, in order to improve the reliability and economy of power distribution operation, all power supply units have attached great importance to the live working of power distribution. Many units have set up or reorganized work teams, and the live working of power distribution will face a new development period. In order to ensure the safety of live working personnel and equipment, it is necessary to conduct in-depth analysis and Research on the safe operation mode, human protective equipment and operation requirements of live working in power distribution

1 live working mode of distribution line

live working of distribution line can be classified according to insulation mode or insulation tools used

1.1 classification by insulation method

1.1.1 indirect operation method

is an operation method with insulation tools as the main insulation and insulation wearing appliances as the auxiliary insulation

this operation method refers to the method that the operator keeps a sufficient safe distance from the live body and works through insulating tools. Moreover, all parts of the human body are kept away from the electrified body and the grounding body through insulating protective appliances (insulating gloves, insulating clothes, insulating boots), and the human body is not at ground potential. Therefore, this operation method should not be mistakenly called ground potential operation method

1.1.2 direct operation method

refers to the method that operators directly approach the live body with the help of the insulating arm or insulating ladder of the aerial work vehicle, and all parts of the human body wear insulating protective equipment for direct operation. This operation method should not be called equipotential operation method in name, because when working with insulating gloves, human body and electrified body are not equipotential

in live line operation of distribution lines, whether direct operation method or indirect operation method is adopted, if it is divided according to the human potential of operators, it belongs to intermediate potential operation method

1.2 according to the classification of insulation tools used

in the live line operation of distribution lines, it is divided according to the main insulation tools used. The frequently used operation methods are as follows:

1.2.1 operation method of insulating tools on the pole

operators climb the pole to the appropriate position through pole climbing appliances (foot buttons, etc.), fasten safety belts, and maintain a safe distance suitable for the system voltage, Then the insulating rod with different tool accessories at the end shall be used for operation. When this operation method is adopted, first, the longitudinal insulation protection between the electrified body and the ground is composed of insulating tools, insulating gloves and insulating boots, in which the insulating tools play the role of main insulation and the insulating boots and insulating gloves play the role of auxiliary insulation; Second, the horizontal insulation protection between electrified bodies and people or between electrified bodies of different phases is composed of insulation shield and insulating clothes, so as to avoid phase to phase short circuit or phase to ground short circuit caused by excessive range of human action. The characteristic of this operation method is that it is not limited by traffic and terrain conditions, and it can be operated at the pole position that cannot be reached by the overhead insulated bucket truck. However, the mobility, convenience and air operation range are not as good as those of insulated bucket trucks. The on-site monitoring and management personnel shall mainly monitor the safe distance between human body and electrified body and the minimum effective length of insulating tools. Before operation, they shall strictly check the electrical insulation strength and mechanical strength of the tools used

1.2.2 operation method of insulated platform

insulated platform is usually composed of insulated herringbone ladder, one legged ladder, insulated car body, etc. The operators can operate through insulating tools with the quick connection method between rings, or through insulating gloves with the direct method. The insulating platform plays the role of main insulation between phases

whether it is indirect method or direct operation method, in general, insulation shielding and isolation tools should be used to shield or isolate the charged bodies of adjacent phases before operation on the repaired phase. At the same time, operators should wear a full set of insulation protective equipment. When working directly through insulating gloves, protective gloves against abrasion or puncture shall be put on the rubber insulating gloves

1.2.3 operation method of insulated bucket truck

the insulated bucket truck is used for live line operation, which has the advantages of convenient lifting, strong mobility, large operation range, high mechanical strength, good electrical insulation performance, etc. Insulated bucket trucks for live working have been developed in European and American countries since the 1930s, and have been widely used in live working of power transmission and distribution lines by the 1950s. The insulating arm of the insulated bucket truck is made of glass fiber reinforced epoxy resin material and wound into a cylindrical or rectangular cross-section structure. It has the advantages of light weight, high mechanical strength, good insulation performance and strong hydrophobicity. It provides insulation protection for the human body that can greatly improve the mechanical performance during live line operation. Some insulating buckets are single-layer buckets and some are double-layer buckets. The outer bucket is generally made of epoxy FRP, and the inner bucket is made of polytetrafluoroethylene. The insulating bucket shall have high-strength electrical insulation, and form the longitudinal insulation between the phase and the ground together with the insulating arm, so that the leakage current of the whole vehicle is less than 500 Ω. At the same time, during operation, if the insulating bucket touches two-phase conductors at the same time, surface flashover shall not occur

the positioning of the working platform of the insulated boom truck can be directly operated by the operators in the upper platform of the insulated boom, controlled by the personnel on the lower bridge, and hydraulically controlled at the upper and lower parts of some working trucks. The operation platform has the function of horizontal and vertical rotation, and can move horizontally or vertically parallel to wires or poles. Live working with overhead insulated bucket truck for power distribution is a convenient and flexible operation method. 4) the size of the initial crack in the ceramic body is equivalent to the mm level microstructure. It has a wide range of applications and low labor intensity

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