Introduction
Because the liquid high -temperature sulfide silicon rubber has excellent insulation performance and good processing performance, its liquidity performance is very good. Use this material processing cable terminal to control the cone and the overall pre -production intermediate connector. Flows smoothly to every small narrow area of the inner cavity of the mold.
There are two major categories used by theocytic power cable accessories of 10kV and above voltage levels in China: the first category is the attachment of the cold shrinkable cable, and the second category is the prefabricated cable attachment.
More than 95%of the cold -shrinkable cable accessories are made of silicone rubber materials. About 80%of the prefabricated cable accessories are made of silicone rubber materials.
1. Cold cable accessories
Cold shrinkable cable attachments are the high elasticity of silicon rubber materials, and high -temperature sulfide silicon rubber is used to sulfide into a tubular component of various structured pipe components. When the inner diameter of the component is expanded to about 3 times, the special plastic support piping is placed in the tubular components to keep the silicon rubber pipe components expand. These expansion status parts become a component of the clue cable accessories.
During the on -site installation, the components of these expansion states are put into the processed cable end or connector, and the internal support pipes (bar) are removed, and the silicon rubber part is automatically shrinking and tightly pressed on the cable insulation. That is, it is a cable attachment. Because it is the elastic retreat of silicone rubber at normal temperature, rather than heating shrinking with fire like heat shrinking cable attachments, it is commonly known as cold shrinking cable accessories.
Cold cable accessories have an important requirement for silicone rubber. After two years of expansion and storage, they can still be reset, and they can still shrink and press on the cable insulation.
Introduction to high -pressure cable terminals
110-220kv cross-linked polyethylene is a classic product of the insulation cable terminal. It is a porcelain sleeve (or composite sleeve) cable terminal. The cable terminal is characterized by super insulation performance; good weather resistance; long-term operation history Essence
3.1 Tube -type high -voltage cross -linking cable terminal structural characteristics
① Put the specific shape of the prefabricated rubber electrical stress control cone on the insulation of the cable with the external shielding of the cable;
② Use the semiconductor rubber material and the combination of the semi -conductive rubber material with a specific curve inside the cone and the combination of insulating rubber materials to improve the distribution of the end of the cable;
③ Relying on the elasticity of the prefabricated rubber stress cone material, the basic constant interface pressure is applied to the power field strength at the end of the cable.
3.2. Core components of high -pressure cross -linking cable terminals
Prefabricated electrical stress control cone shape features:
Rubber electrical stress control cone is an effective way to control the end -end electric field of the cable:
The pre -shielding of a specific shape of the prefabricated electrical stress control cone with a specific shape of an insulating rubber and conductive rubber combined by an insulating rubber and conductive rubber is set at the outside of the cable. The distribution of electric fields at the end of the cable can be effectively controlled to prevent the cable terminal from discharge.
Third, liquid silicon rubber processing high -pressure cable attachment core components can improve product quality
1. In the early days, people used the electrical stress control cone and the intermediate joint of the meter -C rubber processing electrical stress. The disadvantage is that the materials are relatively hard and difficult to install. Second, the process performance in the process of processing products is not good. The quality control between the interface between the insulation rubber and the conductive rubber is difficult. Due to the poor liquidity of the materials, the border transition surface is not neat, and it will form a convex or depression, a set, a suit, a suit. A air gap state will be formed on the insulation of the cable. Third, there are serious hidden quality hazards: there are reports that the 220kV trifuna ethylene rubber insulating intermediate joint generates the sudden cracking of rubber insulation parts during operation and causes discharge breakdown. In addition, the 220kV trifuna ethylene rubber insulating intermediate joint is also cracking during normal pre -expansion during normal pre -expansion. The reason is that the elongation of the ethylene rubber is low, which directly reduces the mechanical strength of the intermediate joint.
2. In the past 10 years, due to the emergence of new silicon rubber materials, cable accessories manufacturing companies have adopted the electrical stress control cone and the overall prefabricated intermediate joint of the silicon rubber manufacturing cable terminal. The processing performance of solid high temperature sulfide rubber has greatly improved compared with the BMM rubber.
In recent years, the emergence of liquid high -temperature silicon sulfide rubber has provided basic conditions for us to create high -performance cable terminals with electrical stress control cone and overall pre -production intermediate joint.
3. Because liquid high -temperature sulfide sulfide rubber has excellent insulation performance and good processing performance, its liquidity performance is very good. It is used for this material processing cable terminal. Rubber can smoothly flow to every small narrow area of the inner cavity of the mold. It can maintain accurate R curved surface transition between the conductive cone (conductive pipe), form a neat interface interface, and adhere to the conductive cone (conductive pipe) tightly, good combination, and adhesion between insulation silicon rubber and conductive silicon rubber. The closer the interface, the smaller the interface, the smaller the air gap, the more the interface electrical properties between the two between the two are better.
4. The product of liquid silicone rubber electrical stress control cone and the middle joint compared with the EPR (Sanyuan Ethyl Ciber Rubber) products, which have the following advantages:
① During the installation of cable attachment products, there will always be a certain unevenness after the cable insulation surface is treated.
The gaps in the insulation interface of the ethylene rubber products and the cable insulation interface are not easy to make up, which will reduce performance.
The material of the liquid silicone rubber products is soft. After the set, the gap of the interface can be filled, which can make up for electrical defects caused by incomplete contact.
② The diameter of the EPR cable accessories and the outer diameter of the cable is about 5mm, while the diameter delegation that can be allowed to allow the sub -rubber cable accessories can reach more than 10mm. Disposal has the following advantages:
A. It can make up for electrical defects due to incomplete contact.
b. It can make up for changes in the insulation outer diameter caused by temperature changes. C. It can make up for the gap caused by the curved cable.
③ When the rubber cable attachment is used, due to deformation, a stress relaxation phenomenon is generated. Silicon rubber has a stress relaxation ability that can withstand 10 times than EPR.
EPR decreased by 20%after 30 years. Even if the diameter of silicon rubber was nearly twice as much as possible, the stress relaxation after 30 years was basically unchanged.
5. We will take the electrical stress control cone sleeve processing of liquid high -temperature sulfide silicon rubber processing on the special test equipment for testing. It is found that it can improve the local discharge starting voltage of the product.
Fourth, the requirements and discussions of the electrical cable attachment to silicon rubber materials
1. The attachment to the power cable is a relatively special product. The product should bear the high -electric field generated by the cables at the interior of the cutting outlet during the operation of the cable. Short -term short -circuit temperature 250 ℃).
2. The power cable terminal is generally installed outdoors. After the installation, the product is exposed to the atmosphere. In summer, the sun must be afforded and the ice and snow must be affected in winter; Voltage.
3. Special requirements for Silicon Rubber
China’s 10-35kV power cable accessories are very large. At present, the largest use of the cold-shrinkable cable is currently used. Prefabricated products are very small due to inconvenient installation.
Cold cable accessories have an important requirement for silicon rubber: after two years of expansion and storage, it can still be reset after two years, and it can still shrink and tighten the pressure on the cable insulation. This special requirement is a challenge to our development of silicon rubber technicians.
