Composite insulator end seal problems and solutions

Problem

At present, most of the domestically produced organic composite insulator end connection structures are wedge-connected, and some manufacturers adopt a foreign-style crimp connection structure. However, both the wedge type and the crimp type have problems in the sealing process of the joint between the end fitting and the core rod. Most domestic manufacturers use the sealant produced by Shanghai Special Rubber Factory. There are some hidden dangers in the process of manually applying sealant.

1) First, it is inevitable that the composite insulator slips between the mandrel and the metal fitting during long-term load operation (wedge type). When the sealant and the metal fitting have poor adhesion, the slight slip is enough to make the seal open. When the sealant is not elastic enough, the excessive slip can break the sealant.

2) Secondly, the domestic production of sealant is mostly room temperature silicone rubber, its anti-aging performance is not as good as high temperature vulcanized silicone rubber, in the case of corona in the end of the gold fittings, may lead to premature aging. For products of 110kV and below, the use of pressure equalizing rings, or the installation of pressure equalizing rings of 220kV and above will be even more dangerous.

3) Since the process of applying the sealant is manual application, there are some uncertain factors, the operation process is not easy to control, and it is not convenient to manage and control the product quality.

Solution

The gold fittings and the mandrel are directly molded together with high temperature vulcanized silicone rubber at the end of the composite insulator (see Figure 1). The new process has simple structure, easy production, safe and reliable use, avoids the quality defects existing in the above analysis, and improves the anti-aging performance. Because it is molded by high-temperature vulcanized silicone rubber, it also reduces the sealing process, reduces the interface, saves the sealant, improves the sealing performance, and solves the brittle fracture of the mandrel due to the poor sealing. problem. What is more gratifying is that after adopting this structure, under the same conditions, the dry arc distance and creepage distance are effectively increased, and the lightning surge voltage level is improved, which can be increased by more than 15% according to laboratory test results. In the multi-ray activity area and the vast mountainous area, this structure can improve the flashover voltage of the lightning strike and ensure the safe operation of the power grid.

The traditional composite insulator is sealed by manual sealing. The rubber compound used is room temperature vulcanized rubber. The anti-aging property is low. Especially in the harsh environment, the corrosion will make the sealant age faster, and the sealing process is difficult to control. The core rod is eroded to cause an accident; and the new sealing process can improve the safety factor of the composite insulator in the operation of the power grid, prevent accidents caused by poor sealing, and be more reliable in product quality!