Causes and preventive measures of the hottest line

2022-08-02
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Line fault causes and hardness preventive measures for the work hardening zone around the indentation

overhead lines erected in the open air have been affected by natural conditions and the surrounding environment for many years, so there are many accidents. Patrol inspection and maintenance should be strengthened during operation to prevent accidents

1 line fault causes

(1) influence of natural factors:

① influence of strong wind: excessive wind force inclines the suspension insulator string, increases the sag, reduces the air insulation gap, and is prone to phase to phase short circuit and wire burnout accidents. When the wind force exceeds the mechanical strength of the pole and tower, the pole and tower will be inclined, damaged, the conductor will vibrate, jump and touch the wire, which may cause short circuit and quick tripping of the circuit breaker

② influence of rain: drizzle will cause flashover and discharge of dirty insulators and damage insulators. The torrential rain will cause the river to surge, flash floods and landslides, causing pole collapse and disconnection

③ lightning impact: in thunderstorm season, the line is struck by lightning, and lightning overvoltage causes insulator flashover, burn or breakdown explosion, resulting in circuit breaker tripping

④ effect of heavy fog: in heavy fog weather, the relative humidity of the air is high, the flashover voltage of the insulator along the surface decreases, causing flashover, discharge and damage to the insulator. In serious cases, breakdown flashover occurs, which will cause a large area of power failure

⑤ heavy snow impact: in severe storm and snow weather, the conductor stress and load increase, and pole fall and wire break accidents are easy to occur; When the ice disappears and the snow melts, the insulator is prone to flashover

⑥ icing effect: when serious icing occurs on the line conductor, the conductor will be broken. When the icing falls off, the conductor will jump or even flashover

⑦ temperature effect: the conductor has the property of thermal expansion and cold contraction, and the conductor tension changes with the temperature. When the temperature is high in summer, the conductor is stretched and sag becomes larger, which is easy to cause discharge and grounding short circuit accidents at the crossing

⑧ impact of pollution flashover: in the area where the overhead line passes, due to the smoke exhaust of the factory, salt fog brought by the sea breeze, dust floating in the air and dust blown by the strong wind, it gradually accumulates and attaches to the surface of the insulator, causing insulator flashover and large-area power failure

⑨ corona effect: the phenomenon of free discharge in the air around the conductor under the action of strong electric field

(2) influence of surrounding environment and foreign objects:

① the lines in different areas are affected by environmental conditions, and the lines in the chemical industry area are prone to flashover discharge due to pollution

② the lines in cities and towns are easily affected by foreign objects such as antennas, kites, flagpoles, etc

③ in rural areas, livestock are often tied to the pole, and scratching on the pole will shake the pole, which is easy to cause short-circuit accidents

④ the line near the river channel is vulnerable to scouring

⑤ the roadside line is vulnerable to collision by vehicles, and the boom of the offline crane touches the line, causing phase to phase short circuit or even disconnection

⑥ the woods are close to the line and fall down on the road in case of strong wind, resulting in pole falling and line breaking accidents. The treetops under or on both sides of the power line are easy to touch the conductor, resulting in grounding, spark or short circuit

⑦ crow may cause line grounding or short circuit accidents by nesting and stopping on poles and towers, flying or fighting between conductors, and shooting birds near conductors

⑧ overvoltage will be generated when the circuit breaker is pulled and closed during line shutdown and power transmission, which will damage the insulator

2 preventive measures

(1) grasp the seasonal and environmental characteristics and take corresponding anti accident measures:

① pollution prevention: clean the insulators in time. Before the heavy fog season or the rain and snow season with a temperature of about 0 ℃, pay close attention to the testing and cleaning of the insulators to prevent flashover accidents on the insulator surface caused by leakage current

② lightning protection: before the thunderstorm season, the test, inspection and installation of lightning protection equipment shall be done well, and the resistance of the grounding device shall be tested on schedule and the damaged insulation wire shall be replaced

③ heatstroke prevention: before the arrival of high temperature season, the sag of each phase conductor shall be checked to prevent accidents due to the increase of temperature sag

④ cold prevention: before the arrival of the severe cold season, attention should be paid to the existence of these problems, so that China's plastic machinery industry can not meet the horizontal line sag of foreign plastic machinery as soon as possible. If it is too tight, it should be adjusted to prevent line breakage

⑤ antifreeze: in heavy snow season, pay attention to the snow and ice on the conductor, and timely remove the snow and ice on the conductor to prevent wire breakage

⑥ wind prevention: before the wind season, the stay wire and pole foundation shall be reinforced, the sag of each phase conductor shall be adjusted, and the sundries around the line and nearby trees shall be cleaned to avoid accidents caused by branches touching the conductor

⑦ flood control: before the arrival of flood season, various measures shall be taken to prevent pole collapse for the pole foundation instability caused by scouring near the river and excavation nearby

⑧ bird prevention: bird damage prevention is a highly seasonal task in power line maintenance. Bird prevention windmills, bird prevention rings, reflectors, bird prevention needle plates, etc. are installed to scare birds and prevent them from nesting and perching on poles (towers)

⑨ corona prevention: spherical accessories shall be installed at both ends of low-precision bus and jumper, and the clamp nail cotter pin sealing device shall be used at the connection between tension clamp and insulator bowl head to reduce the exposure of parts with small radius of curvature of high-voltage equipment to the air and prevent corona

(turn on the plotter switch 2) strengthen the line patrol to ensure the healthy operation of the line:

① regular patrol: generally, the patrol shall be conducted once a month. When there are many bird damage accidents in spring and the peak power consumption for drought resistance and waterlogging drainage in summer, the patrol times can be appropriately increased with the change of seasons

② special patrol inspection: in case of sharp climate change (strong wind, rainstorm, dense fog, conductor icing, etc.), natural disasters (earthquake, flood, forest fire, etc.) and major political program activities, the number of patrol inspection shall be increased as a special case

③ fault patrol inspection: in case of line fault, tripping or grounding, patrol inspection shall be organized in time

④ night patrol inspection: in order to check whether there are flashover, heating (red), sparks and other phenomena at the joints of line insulators and conductors, it is best to conduct patrol inspection every six months at the peak load at night without moonlight

3 conclusion

in order to ensure the healthy operation of the line, in addition to full consideration in the design and installation, it is necessary to strengthen the line patrol inspection, regular maintenance, operation and maintenance management, seriously implement the anti accident measures, assign full-time personnel to be responsible for line patrol and protection, organize training and assessment from time to time, improve the professional skills and strengthen the hearts of employees; The line patrol inspection personnel shall conduct patrol inspection as required, check the health status of the line, find out the existing defects and problems, so as to formulate the maintenance plan, eliminate the accident in the bud, and ensure the safe, economic and reliable operation of the line

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