Development and safety analysis of live working in

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Analysis on the development and safety of live working in high voltage distribution

the economic benefits created by live working include calculable and difficult to calculate. The calculable part can be summed up in two forms: direct benefit and social benefit. The direct benefits are obtained by the power sector; Social benefits are due to more power supply to factories and mining enterprises, so that manufacturers and local finance get more benefits. The benefits that are difficult to calculate are reflected in reducing power supply accidents, improving power supply reliability, eliminating adverse political effects, and facilitating people's lives.

1. The benefits that are difficult to calculate are shown in the following aspects:

(1) live line operation can eliminate equipment defects in a more timely manner than power-off operation, thus reducing or avoiding the time of equipment "running with faults" and reducing the accident rate

(2) under the condition that China's power supply equipment is generally lack of sufficient standby equipment, power failure operation is bound to destroy the mutual standby state of power supply equipment and reduce the level of safe operation

(3) widely carrying out live line work will effectively reduce the total number of equipment power outages every year, thus greatly reducing the "misoperation accidents" in equipment switching operation, the "accidental pole landing and electric shock" and "accidental grounding" in power outage operation

(4) live line operation is not constrained by time, and it can realize the planned arrangement of the whole year to complete the maintenance tasks, so as to avoid the large Corps operations that often occur in power outage operations, and reduce the invalid working hours and costs of human and material resources in the round-trip assembly process. Up to now, due to the sophisticated tools, exquisite operation technology, skilled technology and other factors, the maintenance efficiency of more than 50% of the projects has exceeded the level of power outage maintenance

II. Working environment of high-voltage power distribution live line work

1. The working place is located in the urban area, with noisy environment, bucket truck noise, etc

2. There are many accidents of distribution line equipment, frequent operations, and many line abnormalities

3. Complex lines, multi circuit and high and low voltage common pole erection

4. The distribution line equipment is seriously rusted

5. The distance between phases and to the ground of the distribution line is small

6. Work at height

therefore, the difficulty and labor intensity of its operation will be greater than that of live line operation with high voltage level due to its working environment

III. live working mode

due to the reasons of tools, equipment and protective appliances, the previous live distribution work mostly used shielding clothes, using overhead insulated bucket trucks or ground potential for indirect operation. According to the safety distance determined by the regulations, the on-site environment and the structural conditions of electrical equipment of power distribution live line work, it can be seen that in order to ensure safety, indirect work should be the main work in power distribution live line work. Now, with the development of live working technology at home and abroad, the performance and indicators of insulating clothing are getting better and better, and the insulation protection tools are also more reliable and portable. In particular, foreign insulating tool products are better than domestic products. Basically, all units use foreign insulating clothing and insulating protective equipment. In addition, many portable electric hydraulic maintenance tools abroad have greatly reduced the labor intensity of operators. Therefore, at present, full insulation operation method is mostly adopted

you need to carefully adjust the scale position of the fastening screw. Insulation operation method is a professional term we often hear. Through practice, we doubt this title, which is still dangerous to some extent. Therefore, I am willing to discuss with colleagues. The word "full insulation" itself has a certain absolute nature, and producers at the grass-roots level often recognize it as "absolutely safe or safe", which is very dangerous. The falling edge of the full pulse corresponds to the concept of insulation at the zero crossing point of the rising edge of the alternating load waveform. It refers to the concept that after wearing insulating clothes and using insulating protective appliances to form insulation with the grounding body on the insulated bucket truck, the operators wearing insulating clothes directly repair or install live equipment, or after installing the insulating platform on the tower, Operators wear insulating clothes and protective equipment and stand on the platform insulated from the grounding body to work on live equipment. No matter which state it is, its insulation property is relative. The real safety is to establish a correct safety thought, behavior and strict rules and regulations to reflect, and cannot mechanically abide by some tools to ensure safety

the method of dew condensation on the light pipe due to air saturation in high-voltage power distribution, especially 10kV, from the application point of view, whether it is the work on the pole or the work using the insulated half boom, according to the actual working methods and tools used, it can not be distinguished by the simple ground potential, equipotential, intermediate potential, direct and indirect methods, but should be regarded as the comprehensive nature of the possible use of more than one method. At the same time, we must comprehensively consider the actual structural characteristics of the line, the complexity of electrical equipment and the safe air distance. During operation, in addition to the safety insulation protection of human body, we should organize effective insulation shielding, isolation and other measures for live electrical equipment and non live grounding body components according to their actual performance characteristics, so as to form a variety of scientific and reasonable guarantees on the operation site

IV. characteristics and existing problems of live working in high-voltage distribution

1. Safety must be considered in live working in high-voltage distribution first.

the voltage of high-voltage distribution network is lower than that of transmission, the air spacing between three-phase conductors is small, and the distribution facilities are dense, which makes the range of live working personnel narrow, and the operators work within the limited scope of operation activities, plus the invisibility of high voltage and the operators work at heights of poles, Operators often have some dangerous behaviors, and it is easy to touch other power facilities at different potentials. Therefore, if the safety measures in production are not comprehensive, the operation mode is not standardized, and the tools are not used at the right time, it is easy to have single-phase grounding, phase to phase short circuit, and even personal injury and death accidents

2. Improper safety protection measures

safety protection measures are one of the important measures to ensure the safety of production personnel in live line operation. Therefore, the first important measure of safety protection is to use good insulating tools to isolate or shield live bodies and grounding bodies during operation; Second, operators should wear a full set of qualified insulation protective equipment. The problem is that there are some problems in the insulation protective clothing produced by our country at present, so most of them use products from abroad. Among these products, there are many kinds. When selecting enough devices, special attention should be paid to the electrical parameters provided by them, and they should be reasonably selected and used correctly according to the purpose. We believe that the correct method of use depends on the live working mode adopted, and its insulation and auxiliary insulation objects are determined according to the mode. For example, when indirect operation method (i.e. ground potential method) is adopted, the insulation tool is the main insulation, and the insulation protective equipment worn by the operator is the auxiliary insulation; If the insulated platform on the pole method or the insulated bucket truck direct operation method is adopted, the insulated platform and insulated bucket truck are the main insulation at this time, and the insulation tools of the operators are auxiliary insulation. In the direct operation method, it is very important for people to wear a full set of insulating clothes as backup protection. Its advantages are: first, it can shield the electrified body, and protect the personal safety of operators when the isolation is incomplete or the shielding device falls off accidentally; Second, if the insulation shielding tool itself has insulation defects or accidental electrical damage, it can still prevent the human body from touching two-phase and single phase to ground at the same time, resulting in phase to phase or automobile and aviation enterprises are constantly looking for materials that are more durable or can withstand higher stress. In short, the layout principle of insulation protection measures must be to make the operators in relative phase, relative ground and human body to ground in relatively good insulation and isolation conditions. Therefore, for insulating clothing or insulating isolation tools, not only high breakdown voltage, but also high surface flashover voltage and small surface leakage current are required

live line operation of high-voltage distribution will once again be promoted to a climax in China. Due to the fierce momentum and the objective problems mentioned above, it will inevitably lead to the lax allocation of production and technical personnel, the lack of rationality and scientificity of the allocation of tools and instruments, especially the live line production management, which is prone to some loopholes. In such a state, it is difficult to avoid live line operation without accidents

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