Integral prefabricated joints for power cables of 500kv and above

Abstract

The invention relates to a cable accessory in the field of a power cable transmission system, in particular to an integral prefabricated joint for a power cable with 500kV and over 500kV. The integral prefabricated joint for the power cable with 500kV and over 500kV comprises an integral prefabricated insulator (1), a sealant (2), a metal protection cover (3) and a conductor connecting piece (4);the integral prefabricated insulator (1) is arranged outside the conductor connecting piece (4); the sealant (2) is arranged outside the integral prefabricated insulator (1); the metal protection cover (3) is arranged outside the sealant (2); the integral prefabricated insulator (1) comprises a stress cone (1-1), a shielding tube (1-2), an insulator (1-3) and an outer shield (1-4); and the integral prefabricated insulator (1) is made from liquid silicon rubber. The integral prefabricated joint has the advantages of stable and reliable performance, high yield, low integrated cost, simple manufacturing process, low manufacturing cost, and good product quality.

Description

technical field [0001] The invention relates to a cable accessory in the field of power cable transmission system, in particular to an integral prefabricated connector for power cables of 500kV and above. Background technique [0002] At present, in the power cable transmission system with a voltage level of 500kV and above, the cables are mostly XLPE insulated power cables, and the joints are used for the connection between XLPE insulated power cables and cables to realize the transmission of electric energy. . With the construction of large-scale hydropower stations, pumped storage power stations, and UHV power grids, the use of joints is increasing. In power cable connection systems of 500kV and above, joints are the weakest link and are prone to failure. The rate accounts for more than 70% of the entire cable connection system, and the reliability of the joint directly affects the reliability of the power transmission system. Joints are divided into insulated joints an...

AI Technical Summary

Problems solved by technology

[0004] (1) It is difficult to control the quality of the material for making the overall prefabricated insulation. The material of the overall prefabricated insulation is mainly a terpolymer of ethylene, propylene and non-conjugated dienes. There are various additives in the mixing process In addition, the formula is complicated and it is difficult to control the quality of the material; the viscosity of the material is high, the molding process is poor, and the yield of the overall prefabricated insulation is only about 60%

[0005] (2) The production process is complicated, and the molding equipment required for processing prefabricated insulating parts is under great pressure, bulky and high in production cost

Because the viscosity of EPDM rubber after plasticization is very high and its fluidity is poor, it needs tens of megabytes of pressure to inject it into the cavity. During the injection process, the cavity and equipment need to withstand very high pressure. Due to the molding mold The volume is very large, and a special large-scale rubber injection machine with a large tonnage and a large mold are required for rubber injection molding, and the materials used must be injected at one time. Therefore, the overall prefabricated insulating parts of the overall prefabricated joints of power cables of 500kV and above are produced. The tonnage of the required rubber injection machine should reach more than 1,600 tons, and the single injection of more than 80 liters can meet the requirements. Such equipment is large in size and high in equipment cost, and the increase in equipment cost makes the entire production cost extremely high.

[0006] (3) Due to the high hardness of EPDM rubber, Shore A60~70, the adhesion to the surface of the cable is poor, resulting in difficulty in product installation and an increase in product failure rate, and the air box of EPDM rubber is aging Post-mechanical properties (aging conditions: 135°C±3°C, 7d), compression set ≤ 15-25%, tensile strength change rate ≤ 20-30%, elongation change rate ≤ 20-30%, material The aging resistance and high temperature resistance are poor, and the product must be operated under the environmental conditions of ≤100°C, the use is limited, and the scope of application is narrow

[0007] Although the existing 500kV and above 500kV overall prefabricated connectors for power cables have the above defects, people have been unable to solve this technical problem for a long time

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