Aerial cables are a way of installing lines for outdoor use, leaning on poles. Aerial cables are usually bare conductors with multiple stranded wires.
Due to the good heat dissipation conditions of the cable, its load capacity is between a 30 and a 40% greater than that of an insulated cable of the same section. This represents a significant reduction in the cost of the line.
Airlines are low cost, low investment, easy to install, to maintain and repair. But it is susceptible to environmental damage (As the rain, Snow, wind, the rays, etc.).
Failures in overhead conductors
(1) On the distribution lines, las Airlines They are arranged horizontally and the distance between the lines is small.
If the same file distance within the arc of the cable is not the same, the oscillation of each cable when strong winds blow is not the same.
This will cause the cables to collide with each other causing a short circuit between phases.. So in construction you should pay attention to the tension of the cable and equalize the chord of the three phase conductors. When the line is checked, if this problem is found, must be resolved quickly.
(2) Tree branches or metal objects falling on the line can also cause a short circuit between phases or even break the cable..
Besides, Excessively tall vehicles passing under the line can also cause a short circuit in the line or an accident. Therefore, a certain distance should be left between the crossed lines.
(3) Due to long-term erosion by moisture, the atmosphere and harmful gases, overhead cables are prone to rust and damage.
Los steel wires and lightning rods are the most prone to corrosion. If during the inspection it is detected that the cable is severely corroded, must be replaced quickly.
Failures in overhead cable insulators
(1) Porcelain line insulators can cause contamination of the porcelain part due to the influence of harmful components in the air.
When encountering wet weather, the dirty part absorbs moisture and causes the conductivity to increase. This will increase power loss and easily cause electric shock accidents..
(2) Unqualified porcelain insulators or aged insulators installed in the line are susceptible to cracking due to flashover under the action of working frequency voltage.
In this sense, Porcelain insulators with flashover marks found during inspection should be replaced in a timely manner.. The new replaced porcelain insulator must pass a tensile strength test.
(3) The porcelain insulator part is damaged by external forces and cracks or breaks occur.. This insulator must be replaced, since otherwise it will cause insulation degradation and flashover accidents..
Failures in overhead cable poles and accessories
(1) Due to the influence of soil and humidity, The decay of wooden posts often causes them to fall.
Therefore, if wooden posts are used, anticorrosive measures must be taken, such as covering asphalt or adding stakes.
(2) Cement posts suffer external collisions, such as car or tractor crashes, etc.
(3) The cable is under uneven tension, which causes the pole tower to lean. At this point the pole must be tightened by adjusting the line.
(4) At the place of driver vibration, the screws of the cable accessory Airplanes can easily fall and accidents can occur..
Therefore, during inspection and maintenance, It is necessary to carefully check whether the contact between the different parts of the accessories is good..
This information is provided by ZMS Cable Group, a professional manufacturer of various cables and related accessories. If you have any questions, Contact us.