Reason analysis
According to the investigation, the areas where the overhead lightning protection wire dropped are all located in areas with high winds. According to experience, there are two reasons for the lightning protection wire dropping due to the wear of the suspension clamp:
(1) Due to the effect of wind, relative movement between the hull of the suspension clamp and the hanging plate occurs, and the hanging plate swings at a small angle around the hanging shaft of the hull. Because the hanging plate is thin, its swinging effect is like a blade cut and groove marks appear, which causes the force section of the hull hanging shaft to become thinner and smaller. When the groove marks reach a certain level, under the weight of the lightning protection wire, the wire clamp If the hull of the ship falls from the suspension clamp, the lightning protection line is dropped and the grounding accident occurs;
(2) The suspension cable clamp is too large or the lightning cable is not tightly pressed. The lightning cable and the cable clamp hull produce relative movement under the action of wind, causing the lightning cable to wear; under the action of wind or strong lightning current, it will be broken. Or burn the lightning protection wire, causing the lightning protection wire to fall off from the suspension clamp, and an accident similar to the above occurs.
Preventive measures
(1) The hanging plate of the hull hanging shaft of the hanging clamp is fixed by a bolt. There is a flat gasket in the bolt. The gasket covers the connecting part of the hanging shaft. If the gasket is not opened, it is difficult to find the hull hanging shaft. Therefore, when inspecting the degree of wear of the hanging shaft, you must remove the plug and open the gasket. At the same time, you should also pay attention to temporary measures to prevent the lightning cable from falling during the inspection.
(2) In order to prevent the abrasion of the lightning conductor, the size of the suspension clamp should be selected according to the cross section of the lightning conductor. During the construction, the aluminum tape of the lightning conductor at the clamp should be wrapped and the lightning conductor should be pressed tightly.
(3) In the line design, there are only requirements for the load of the fittings, and no inspection is required for other strength parameters. Therefore, in areas with strong wind and high wind deviation, when selecting suspension clamps for line design and construction, you should consider choosing wear-resistant clamps (such as various alloys) and suspension clamps with wind-proof components.
(4) In ordinary line maintenance work, especially the annual overhaul of the line, it should be carried out in strict accordance with the regulations and specifications, and all types of suspension clamps should be opened and inspected as required.
The inspection of line suspension clamps is a link that is often overlooked in line maintenance. While strengthening the construction technology and material selection, it is also necessary to strengthen ordinary maintenance and management, and set up accounts for the pole sections that are prone to suspension clamps. , Shorten the inspection cycle of the wire clamp, and increase the inspection items of the hanging wire clamp in the daily inspection.