Analysis on safety protection measures for live li

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Analysis of safety protection measures for live line work

live line work can be divided into indirect work method, intermediate potential work method and equipotential work method according to the potential of human body. Indirect operation method refers to that people are at ground potential and work on live bodies through insulating tools instead of hands; Intermediate potential operation method refers to the operation method of using insulating tools to contact live bodies when the human body is insulated from the ground; Equipotential operation method refers to that when the human body is insulated from the ground, the staff directly work on the live body, etc. this operation method is also called direct operation method

I. Basic requirements for live line work safety

1. The current through the human body must be limited to less than 1 Ma of the safe current

2. The intensity of high-voltage electric field must be limited to a value that is not harmful to personal safety and health

3. The distance between the working personnel and the charged body should ensure that there will be no flashover discharge in case of various overvoltages in the power system. The safety distance between the person and the electrified body shall not be less than the value specified in the safety work regulations of electric power industry

4. Live line operators must participate in strict technical training, and can only work after passing the examination. Special personnel shall be assigned to supervise the operation

5. For complex and difficult live line work, it is necessary to conduct on-site investigation, prepare corresponding operation process plans and strict operation procedures, and take reliable safety technical organization measures

6. Live line work should be carried out in good weather

(II) safety technical requirements when working with insulated operating rods and insulating tools

when working with insulated operating rods on live line 2. The test material cutting method adopted should not change the characteristics of the part of the test material used to provide subsequent heat treatment samples. The operator is at ground potential or intermediate potential, and maintains a certain safe distance from the live body, and uses various insulating tools to work. In terms of safety, this method mainly requires that the insulation strength of the insulation tools used must be greater than the maximum overvoltage that may occur in the system on the basis of meeting the safety distance

most general insulating tools are equipped with metal parts. For example, the commonly used operating rod, for the sake of the representative of domestic experimental machine manufacturers, Jinan experimental machine factory adapts to different voltage levels and is convenient to carry. It is usually assembled from 2 to 3 sections, and there are generally metal joints between them. Different operating heads are installed at the end of the operating rod according to different work needs. For example, the hooks for push-pull disconnectors or drop-out fuses are gradually accelerated with the pace of urbanization in China, and various metal instruments for spring pins are taken from Paul Gallen of NCC and Christian wolfsberger of Engel. When calculating the length of insulating rod, the length of metal parts must be subtracted. Generally, the length of the insulating tool after subtracting the metal part is called the effective length. The effective length of insulated load-bearing tools and insulated ropes shall not be less than the value specified in the safety work regulations of electric power industry

when using indirect operation method and intermediate potential operation method, special attention should also be paid to the problem of electrostatic induction in safety technology. During operation, the distance between the personnel and the charged body is relatively close, and they often move in the high-voltage electric field. Due to the stray capacitance between the charged body and the ungrounded body and the earth, capacitor charging occurs. When workers are insulated from the ground, once a part of the human body touches the tower, frame or other grounding objects, or contacts the conductor insulated from the ground, personal electric shock will occur, causing casualties

(III) safety technology of low-voltage live line work

1. Low voltage live line work should be supervised by a specially assigned person and tools with insulating handles should be used. When working, stand on a dry insulating object and wear insulating gloves and safety helmet. You must wear long sleeved clothes to work, and it is strictly forbidden to use files, metal rulers, brushes with metal objects and other tools

2. When high and low voltage are erected on the same pole and working on the low-voltage live line, the distance from the high-voltage line should be checked first, and measures should be taken to prevent accidental contact with the high-voltage live equipment. When the low-voltage live wire is not insulated, the staff shall not cross it. When working on low-voltage distribution devices, insulation and isolation measures to prevent phase to phase short circuit and single-phase grounding shall be taken

3. Before putting on the pole, distinguish the phase line and zero line, and select the working position. When disconnecting the conductor, disconnect the phase line first and then the zero line. When lapping conductors, the sequence is reverse. The human body should not touch two thread ends at the same time

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