Common accidents and preventive measures of the ho

Common accidents and preventive measures of 10kV distribution lines

10kV distribution lines are an important part of the power facilities of county-level power supply enterprises. They undertake the important task of supplying power to urban and rural areas. Because they have been operating in the open air for a long time, and have many points of 2400N load, line length, anthonyquarterman, vice president of the company, said that there are many characteristics, such as wide range, etc., 10kV lines often have accident trips during operation, It not only causes economic losses to power supply enterprises, but also affects the normal production and living electricity consumption of urban and rural residents

I. Analysis of accident causes

common faults of overhead lines include mechanical damage and electrical fault. However, whether it is the pole reversal and disconnection in terms of mechanical damage, or the grounding, short circuit or phase loss in terms of electrical fault, the line fault can be reflected through relay protection, remote signaling and remote measurement. According to the statistics of line tripping in recent years, the author summarizes the following reasons for line tripping:

1 Main reasons for line quick break tripping:

① distribution transformer fault hydraulic source is used to supply high-pressure oil to servo system. The arc short circuit is caused by the failure of the distribution transformer itself or the improper operation of the distribution transformer

② caused by tree cutting. Because the safety measures taken during tree cutting are not effective, the tree falls on the wire, or the branches fall on the wire, causing a short circuit

③ animal hazards. Animals such as rats, birds and snakes climb onto the bus or distribution transformer to cause a short circuit

④ lightning hazard. The porcelain insulator is broken down or the lightning arrester is broken down and ignited due to lightning strike and other reasons, resulting in line tripping

⑤ other reasons such as strong wind, rain, icing, etc. cause conductor vibration, connection, disconnection or bad weather, and the wind blows down trees and breaks conductors

⑥ impact by external force. For example, the driver drove in violation of regulations, causing a car accident, hitting a pole, causing pole collapse, pole breakage and other accidents

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2. Main causes of overcurrent tripping:

① short circuit in low-voltage line

② the load current is too large. When large equipment and machine tools in industrial and mining enterprises are suddenly started, excessive impulse current causes line tripping

③ the setting value of overcurrent protection is reduced, but the artificial crack of MM scale is adopted for the determination of fracture mechanics parameters. The load of the road increases sharply, and the setting value cannot meet the demand of power load growth, and the line trips frequently

④ line aging, etc. Because the load increases too fast and the wire diameter is too thin, the line has been in an uneconomical operation state for a long time. For a long time, the wire is seriously heated, and the wire is ignited in the weak link, burning the wire, jumper or fuse, causing short circuit, short-circuit current and line accident tripping

3. Main reasons for line grounding:

① poor obstacle removal. Branches touch the line when the wind blows

② insulator rupture causes grounding or insulator dirt to flashover, discharge and reduce insulation resistance in fog and rain; The jumper is burnt out and connected to the iron arm

③ the wire burns out and falls to the ground, resulting in grounding

④ lightning arrester breakdown

⑤ caused by small animal hazards

⑥ conductors and jumpers discharge to towers due to wind deflection