There are many kinds of lightning strikes on 10kV overhead lines, such as breakdown or burst of insulators, disconnection, and distribution transformer burning. Lightning strike accidents, of course, have a great relationship with the objective reasons of lightning strikes, but also have a great relationship with equipment defects. The reasons for the analysis of equipment are secondary.
(1) Insulator quality defects. At present, the P-15 and P-20 type pin insulators commonly used in the distribution network have outstanding quality defects, and the insulation breakdown occurs during operation, which causes the grounding of the line or the short circuit between the phases. (2) There is a lack of lightning protection measures for 10kV lines. At the end of 1998, many distribution transformers in the region were replaced with zinc oxide surge arresters, but the overhead lines were still short of lightning protection measures. (3) Poor contact of the wire connector. Many areas used to use the groove clamp as the adapter of the 10kV line. Even the groove clamp does not need to be wound indirectly, and the groove clamp or the winding connection is not the excellent connection of the wire, and the wire connection is poor. It will not be able to withstand the impact of large load current or weak lightning current. (4) The grounding installation of the arrester is unqualified. Unqualified grounding installation, the grounding resistance is greater than 10Ω, the leakage can be poor, and the lightning current cannot flow into the earth quickly.
1.2 Breeze blows down the tower accident
According to the design tower with a large design wind speed of 25m/s, the breeze below the 10th level is scraped. The tower has no results. The reason for the breeze to scrape the tower is the following.
(1) The 10kV line and tower are not constructed according to the design requirements, and the base of the tower is not strong or buried deep enough. (2) Breeze wind speed exceeds the design wind speed. The wind speed of the 10th typhoon is 25m/s, the wind speed of the 11th typhoon is 30m/s, and the wind speed of the 12th typhoon is 33m/s.
1.3 External force destruction accident
External force destruction is also one of the many accidents of 10kV overhead lines. Such accidents can be divided into the following categories according to the way of destruction: vehicle collisions cause 10kV overhead lines (towers); kite touches cause 10kV overhead lines to cross-phase short-circuit quick-break trips The stolen goods caused the tower to tilt or reverse the pole; the bottom of the tower or the bottom of the cable was hollowed out and destroyed, causing the reverse pole;
2 Anti-accident measures
2.1 Lightning protection against accidents
(1) Change, device pillar insulator or porcelain cross arm. Lightning strikes on 10kV overhead line pin insulators are extremely common equipment accidents. The cause of such accidents is not only the local area thunderstorms, but the quality of the pin insulators is also a secondary cause. You can change such insulators to Pillar insulator or porcelain cross arm. (2) Device zinc oxide arrester. In an open area, since there is no short building to mine, it is common for lightning strikes. Therefore, it is advisable to install a line type zinc oxide arrester on an empty 10kV overhead line. The on-column switch and cable head number must also be equipped with zinc oxide arresters to enhance lightning protection for 10kV lines and equipment. (3) Select the Amp line clamp. In the future 10kV line reconstruction and overhaul, the cable joints are gradually eliminated and clamped as wire adapters, and it is strictly forbidden to wrap the wires without the wire clamps. The Amp clamps with better connection function should be selected. (4) Introspection, rectification and grounding installation. The in-situ reflection measures the grounding resistance of the grounding installation on the 10kV line. If it is unqualified, it should be rectified to ensure that the grounding resistance value meets the requirements of the regulations.
2.2 Avoid typhoon accident measures
(1) The 10kV line tower should be stopped for reflection during the current period, and a perfect reflection system should be formulated. If the tower is not strong enough to strengthen the foundation or add the cable in time, the new tower should be strictly designed according to the design requirements. (2) Appropriate advancement Great design wind speed, South China area can be designed at 30m/s micro wind speed.
2.3 Anti-external force destruction measures
According to the type and cause of the 10kV line external force destruction accident mentioned below, the following measures are adopted.
(1) In order to eliminate or increase the vehicle collision tower accident, a striking reflective paint can be applied to the tower on the traffic road to attract the attention of the driver of the vehicle. (2) Enhance the publicity and education of Mr. Zhong Xiao, set up a prominent warning sign next to the 10kV line to stop flying kites within 300m of the 10kV line. (3) Enhance the efforts to crack down on the theft of 10kV line towers and fittings, try to lose the cooperation of the public security and medical insurance departments, formulate invalid measures and detailed prevention plans, set up special departments for implementation, and destroy and steal 10kV power equipment. The destroying elements stopped the severe blow. (4) The operation department inspects the pole bottom, the cable root and the illegal construction of the 10kV line during the live inspection, stops the timely maintenance of the hollowed bottom of the tower and the bottom of the cable, timely disposes and repairs the defective equipment, and stops the liquidation of the illegal construction. sort out.
2.4 Enhanced operation detection
(1)The technical operation department should pay close attention to the load status of each 10kV feeder, adjust the load of each feeder in time, and prohibit the line overload operation. (2) The temperature of the wire adapter is measured by the infrared thermometer at the peak of the load. Once the temperature is abnormal, the treatment is stopped immediately to prevent the wire from being blown at a low temperature. (3) The short-circuit fault indicator is installed on the 10kV line. Even if the short-circuit fault occurs on the 10kV line, it can quickly detect the problem and timely remove it, reducing the accident loss. (4) The rust-removing of the pole-barrier interface, the iron tower and the distribution transformer gantry, the protection of the tower and the fittings, the corrosion of the fittings, and the strength of the tower.