Overhead lightning protection line disconnection caused by wear of suspension clamps and prevention

1. Proposal of the problem

As shown in Figure 1, the suspension clamp is composed of a wreck body, a pressure plate and a U-bolt of malleable cast iron. It is hung by two steel plate stamping and hanging plates, and the hanging plates are mounted on the hanging shafts on both sides of the hull. In the use of the illustrated suspension clamp line, there have been many ground faults caused by the suspension of the overhead lightning rod caused by the suspension wire clamp wear problem. Such faults are usually permanent accidents, and lightly cause tripping and power failure. However, it may blow the wire or the lightning protection line, which brings difficulties to the repair of the line and seriously threatens the safety of the power grid.

Figure 1 Suspension clip shape

2, the cause analysis

According to the survey, the area where the overhead lightning protection line is dropped is in the area with large wind power. The reason for the loss of the lightning protection line due to the wear of the suspension line clamp is two:

(1) Due to the action of the wind, the relative movement between the hull and the hanging plate of the suspension clamp is generated, and the hanging plate swings around the hull hanging axis at a small angle. Because the hanging plate is thin, the swinging effect is like the groove mark under the cutting of the blade, which causes the force cross section of the hull hanging shaft to become smaller and smaller. When the groove mark reaches a certain degree, under the weight of the lightning protection line itself, the wire clamp The hull is dropped from the suspension clamp, and the lightning strike line is grounded;

(2) The suspension clamp is too large or the lightning protection line is not pressed. The lightning protection line and the line clamp hull generate relative motion under the action of the wind, causing the wear of the lightning protection line; under the action of wind or strong lightning current, scraping Or the lightning protection line is blown, causing the lightning protection line to fall off from the suspension clamp, and an accident similar to the above occurs.

3, preventive measures

(1) The hanging plate on the hull hanging shaft of the suspension clamp is fixed by the bolt. The bolt has a flat gasket. The gasket covers the connection part of the hanging shaft. If the gasket is not opened, it is difficult to find the hull hanging shaft. Wear condition, therefore, when checking the degree of wear of the hanging shaft, the bolt must be removed and the gasket opened. At the same time, during the inspection, special measures should be taken to prevent the lightning protection line from falling.

(2) In order to prevent the wear of the lightning protection line, the size of the suspension clamp should be selected according to the section of the lightning protection line. In the construction, the aluminum strap of the lightning protection line at the clamp is tightly packed according to the process requirements, and the lightning protection line is pressed tightly. .

(3) In the circuit design, only the load of the metal fitting is required, while the other strength parameters are not required to be inspected. Therefore, in areas with strong winds and large winds, when designing and constructing suspension clamps for line design, consideration should be given to selecting wear-resistant clamps (such as various alloys) and suspension clamps with wind-proof components.

(4) During the normal line maintenance work, especially the overhaul inspection of the line should be carried out in strict accordance with the regulations. The suspension clamps of all types should be opened and inspected according to the regulations.

The inspection of the line suspension clamp is a link that is often overlooked in the maintenance work of the line. While strengthening the construction process and material selection, it should also strengthen the ordinary maintenance management, and set up the account for the pole segments that are prone to wear of the suspension clamp. , shorten the inspection cycle of the clamps, and increase the inspection items of the suspension clamps during daily inspections.