CN102270825A - 500 kV or over 500 kV outdoor terminal of power cable - Google Patents

Abstract

The invention relates to a cable accessory of the electric power transmission system field of the power cable, more particularly to a 500 kV or over 500 kV outdoor terminal of a power cable. The outdoor terminal comprises a sleeve (1), an insulating compound (2), a stress cone (3), and a wrapping material (10). Besides, the terminal also includes an outlet hardware (6), an upper cover plate (7), a lower base plate (8), and a tail pipe (9). The stress cone (3) is installed in the sleeve (1) and is manufactured by liquid silicon rubber. Advantages of the invention are as follows that: (1), the performance is stable and reliable; the finished product yield is high and comprehensive cost is low. The liquid silicon rubber which is the material of the stress cone is produced by simple materials; the material quality is easy to control and the material viscosity is low; and the moulding manufacturability is good; (2), manufacturing technology is simple and the terminal is easy to make with low manufacturing cost. The liquid silicon rubber before vulcanization has low viscosity and good flowability as well as has excellent process moulding performance and needed moulding pressure is low. (3), product quality is good.

Description

500kV and above 500kV power cable outdoor terminal

technical field

The invention relates to a cable accessory in the field of power cable transmission system, in particular to an outdoor terminal of a power cable of 500kV or above.

Background technique

At present, in power cable transmission systems with voltage levels above 500kV and 500kV, cables are mostly XLPE insulated power cables, and outdoor terminals are used to connect XLPE insulated power cables and overhead lines to realize power transmission. transmission. With the construction of large-scale hydropower stations, pumped storage power stations, and UHV power grids, the use of outdoor terminals is increasing. In the power cable connection system of 500kV and above, outdoor terminals are important connectors. The reliability of outdoor terminals It directly affects the reliability of the transmission system.

In the outdoor terminals of power cables of 500kV and above, the stress cone of the commonly used outdoor terminal is a structural type of integral prefabricated insulation. The outdoor terminal of this structure includes casing, insulating agent, stress cone and wrapping material. It also includes outgoing fittings, an upper cover plate, a lower bottom plate and a tailpipe, and the stress cone is installed in the casing, and the stress cone is made of EPDM rubber. The main function of the stress cone is to uniform the electric field and enhance the insulation in the outdoor terminal when the cable insulation shielding is cut off. At the same time, it also provides the necessary pressing force on the surface of the cable to improve the overall insulation level of the terminal. The stress cone is Key components of outdoor terminals. Since the stress cone is made of EPDM material, the current outdoor terminals of power cables of 500kV and above have the following defects:

(1) It is difficult to control the material quality of the stress cone. The material of the stress cone is mainly a terpolymer of ethylene, propylene and non-conjugated diene. Various additives are added during the kneading process. The formula It is complicated and 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 stress cone is only about 60%.

(2) The manufacturing process is complicated, and the molding equipment required for processing the stress cone has a large pressure, a large volume, and high product manufacturing costs. When the EPDM material is processed into a stress cone, the structure of the equipment used for the rubber injection machine is shown in Figure 3. During production, the material EPDM rubber is placed in the barrel 21 and injected into the mold 23 through the injection mechanism 22. Inside, the mold 23 is composed of an upper mold 23-1 and a lower mold 23-2 that match each other. After heating, the material is vulcanized and formed into a stress cone in the cavity of the mold. 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 it requires a special large-scale rubber injection machine with a large tonnage and a large mold to perform rubber injection molding, and the materials used must be injected at one time. Therefore, the production of stress cones for outdoor terminals of power cables with 500kV and above requires rubber injection. The tonnage of the machine must reach more than 1,600 tons, and the single injection of more than 80 liters of glue can meet the requirements of the prefabricated stress cone. Such equipment has a large volume and high equipment cost, and the increase in equipment cost causes the entire production cost to be extremely high.

(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 of the product 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.

Although the existing outdoor terminals of power cables of 500kV and above have the above-mentioned defects, people have been unable to solve this technical problem for a long time.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide an outdoor terminal for power cables of 500kV and above with stable and reliable performance, high yield, simple manufacturing process, easy manufacturing, low cost, and good quality.

The technical solution to achieve the above purpose is: an outdoor terminal for power cables of 500kV and above, including casing, insulating agent, stress cone and wrapping material, as well as outlet fittings, upper cover plate, lower bottom plate and tail pipe, stress The cone is installed in the casing, and the stress cone is made of liquid silicone rubber.

Further, the stress cone is composed of conductors and insulators.

Further, the insulating agent is insulating oil or insulating gas.

After adopting the above-mentioned technical scheme, the present invention has many advantages because the manufacturing material of the stress cone of the key part is improved from EPDM rubber to liquid silicone rubber:

(1) Stable and reliable performance, high yield and low overall cost. The material quality of the stress cone is easy to control, the material of the stress cone is simple liquid silicone rubber, no need to mix separately, the formula is simple, and the quality of the material is easy to control; the material has low viscosity, good molding process, and the yield of the stress cone can reach 90%. Left and right, the performance of the product of the invention is more stable and reliable, the yield rate is high, time and energy are saved, and the overall cost is reduced by more than 40%.

(2) The manufacturing process is simple, the manufacturing is easy, and the manufacturing cost is low. Liquid silicone rubber is a type of silicone rubber compared to mixing type semi-solid silicone rubber and common room temperature vulcanized single-component silicone rubber. Liquid silicone rubber has lower viscosity and better fluidity before vulcanization, and the viscosity is only ternary. 1/10 of ethylene propylene rubber, with more excellent process formability, so the production process is simple, easy to manufacture, the required molding pressure is small, and there is no need for special large-scale rubber injection machines and large molds with high pressure for injection molding. Only ordinary injection equipment and molds can be used to complete the injection molding. For example, if a liquid silicone rubber two-component injection machine is used, the required pressure of the injection machine is only a few megabytes, which is the same as that of an EPDM rubber injection machine. 1/10, the glue injection machine can inject continuously, up to 400 liters at a time, the glue injection volume can meet the needs of stress cone production for outdoor terminals of power cables of 500kV and above, the equipment is small in size, the cost of equipment is greatly reduced, and the production equipment is easy to obtain , it is easy to make, so the manufacturing cost of the present invention is low.

(3) The product quality is good. Due to the low hardness of liquid silicone rubber, Shore A35~45, it has good adhesion to the surface of the cable, easy product installation, low product failure rate, mechanical properties of liquid silicone rubber air box after aging (aging condition: 135°C) ±3°C, 7d), compression set ≤ 15%, tensile strength change rate ≤ 10%, elongation change rate ≤ 10%, the material has good aging resistance and high temperature resistance, and the product is 100~ It can run for a long time under the environmental condition of 150 ℃, the product quality is good, and the application range is wide.

The present invention solves the complicated technical problem existing in the use of EPDM rubber in the prior art with a simple and ingenious technical solution, and solves this technical problem that people have been difficult to solve for a long time.

Description of drawings

Fig. 1 is the structural representation of the present invention with part 20 cables;

Fig. 2 is the structural representation of the injection machine when the stress cone of part 3 of the present invention is made of liquid silicone rubber;

Fig. 3 is a structural schematic diagram of the rubber injection machine when the stress cone of the existing part 3 is made of EPDM rubber.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Embodiment one

As shown in Figure 1, an outdoor terminal for power cables of 500kV and above includes a casing 1, an insulating agent 2, a stress cone 3 and a wrapping material 10, and also includes an outlet fitting 6, an upper cover plate 7, and a lower base plate 8 and the tail pipe 9, the stress cone 3 is composed of a conductor 3-1 and an insulator 3-2, and the insulating agent 2 is insulating oil. The stress cone 3 is installed in the casing 1, and the casing 1 is filled with insulating oil. The wrapping material 10 connected with the tail pipe 9 is wound under the stress cone 3. The stress cone 3 is made of liquid silicone rubber. .

Embodiment two

As shown in FIG. 1 , it is basically the same as the first embodiment, except that the insulating agent 2 is insulating gas, and the bushing 1 is filled with insulating gas.

As shown in Figure 2, when the stress cone 3 of the present invention is made, a liquid silicone rubber two-component glue injection machine is used. The tonnage of the glue injection machine is 100 tons. Put the material of the two-component liquid silicone rubber material of component A and component B in the two rubber barrels 24 of the injection machine, and inject the material into the material tube 27 through the injection pump 26 on the injection frame 25. After being mixed by the mixer 28, it is injected into the mold cavity in the mold 29, and the mold 29 is locked by the clamping mechanism 30, and finally the mold 29 is heated and vulcanized to form the integral prefabricated insulating part 1.

The present invention is not limited to the above-mentioned embodiments, and any technical solution formed by equivalent replacement or equivalent replacement falls within the protection scope of the present invention.

Claims (3)

1. a 500kV and above power cable outdoor terminal 500kV of 500kV and the above power cable outdoor terminal of 500kV, include sleeve pipe (1), insulating compound (2), stress cone (3) and wrapped material (10), also include outlet gold utensil (6), upper cover plate (7), lower shoe (8) and tail pipe (9), stress cone (3) is contained in the sleeve pipe (1), it is characterized in that: described stress cone (3) is made by liquid silastic.

2. 500kV according to claim 1 and the above power cable outdoor terminal of 500kV is characterized in that: described stress cone (3) is made up of electric conductor (3-1) and insulator (3-2).

3. 500kV according to claim 1 and the above power cable outdoor terminal of 500kV is characterized in that: described insulating compound (2) is insulating oil or insulating gas.

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