Silicone rubber (English name: Silicone rubber), divided into thermal vulcanization type (high temperature vulcanized silica gel HTV), room temperature vulcanization type (RTV), of which room temperature vulcanization type is divided into polycondensation reaction type and addition reaction type. High temperature silicone rubber is mainly used to manufacture various silicone rubber products, while room temperature silicone rubber is mainly used as an adhesive, potting material or mold. The hot vulcanization type has the largest amount, and the hot vulcanization type is divided into methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the most amount and product brand), and methyl vinyl phenyl silicone rubber PVMQ (low temperature resistance, radiation resistance) ), there are other silicone rubber, fluorosilicone rubber and so on.

Thermally vulcanized silicone rubber is used as an electrical insulation material, mainly for making composite insulator umbrella sheaths, zinc oxide arrester jackets, climbing umbrella skirts (anti-fouling umbrella skirts), and high-voltage insulation components such as wall sleeve umbrella skirt sheaths , Silicone rubber sheath, arrester sheath, power sheath, drop arrester sheath, drop switch sheath, drop fuse sheath, transformer sheath, isolating switch sheath, protective cover.

1. Application of silicone rubber jacket

According to data, in recent years, silicone rubber composite jackets have been widely used in my country’s power transmission and transformation equipment manufacturing industry, such as zinc oxide surge arresters of 330kV and below, pillar insulators of 252kV and below, current transformers of 126kV and below, and suspension insulators, and they have been widely used in many aspects. The performance is better than the electric porcelain bushing, which greatly promotes the development of the electric power industry and improves the safety of electricity use.

The main advantage:

(1) The silicone rubber jacket adopts high temperature injection molding, which is not broken, has reliable interface quality, protects the core, and provides the required creepage distance. [Use of silicone rubber insulators on power equipment]

(2) The silicone rubber jacket has good hydrophobicity. The water is attached to the surface of the insulating jacket in the form of water droplets, without forming a conductive water film layer, which improves its insulation resistance to pollution flashover. Running in a harsh environment, due to the partial discharge of the high-strength field area and the surface area of ​​the umbrella cover, the hydrophobicity of the silicone rubber surface can be temporarily weakened or lost, but the hydrophobicity of the surface can be automatically restored after a few hours.

(3) The silicone rubber composite casing has excellent resistance to high and low temperature (working temperature is -50 to 150°C), anti-aging (resistance to ultraviolet radiation and ozone), and resistance to tracking.

(4) The composite bushing has excellent electrical insulation properties. The creeping distance of composite insulating sleeves can be reduced by 1/4 compared with the creeping distance of porcelain insulation of the same level, and on products of the same height, the creeping distance of composite sleeves can be much longer than that of porcelain insulating sleeves. .

(5) The composite casing is light in weight, easy to transport, convenient in installation and construction, etc., while reducing the quality of high-voltage circuit breakers and other components.

(6) The mechanical performance is stable and reliable. No dangerous accidents such as fracture and explosion occurred, and other operating equipment was better protected.

(7) The production process is simple, the product qualification rate is high, the production energy consumption is low, and the production process has little environmental pollution.

2. Silicone rubber insulation sheath

With the development of industry, environmental pollution has become more and more serious. The insulation protection of power system substations, especially the insulation protection of old substations, is becoming increasingly important. Personal injury and death accidents caused by pollution flashover, condensation flashover, icing tripping, short-circuiting of small animals, and bare busbars in substations occur from time to time.

The use of heat-shrinkable materials for the comprehensive insulation protection of substations can reduce the occurrence of such accidents, improve the reliability of the power supply system, and is of great significance to the safe operation of the power system. However, when the heat-shrinkable materials are used to transform the power system equipment, they need to be It is extremely inconvenient to disassemble the equipment during power outage, and the insulation sleeve is not tightly connected to the special-shaped joints, which makes it difficult to be fully enclosed. As the temperature of the busbar rises, its service life will be severely attenuated and decreased. Due to the severe moisture absorption of the heat source, the insulation performance of the insulating material is further damaged, which may lead to breakdown discharge. In addition, the casing used in the open air is prone to aging, deformation and damage, short service life, inconvenient replacement of the casing, and high cost.

In order to better eliminate the above shortcomings, silicone rubber insulating sheaths have begun to go deep into the application research of substations. The domestic Tangshan Power Supply Company launched the full insulation treatment of dry-type reactors using silicone rubber in 2008. The insulation effect is excellent. The dry-type hollow reactors are insulated on-site, which proves that the insulation treatment process is advanced and easy. Deal with the dry-type air-core reactor equipment in transit, so as to prevent small animals from entering the equipment interval and causing reactor damage.

The man-made short circuit test proved that the reactor can effectively avoid the interphase short circuit fire accident caused by the climbing of small animals after the full insulation treatment.

3. Silicone rubber insulation sheath characteristics

(1) Silicone rubber insulation coating has strong flame retardancy. Insulating materials for power equipment are required to be flame-retardant. This product is based on rubber-plastic blended polymers and added with excellent flame-retardants to make it flame-retardant to FV-0, meeting the flame-retardant requirements of the power system.

(2) The silicone rubber insulation sheath has strong aging resistance. The service life of the silicone rubber insulating sheath can reach more than 20 years, which greatly reduces the cost of overcoating, the time of power outage and the economic loss caused by power outage.

(3) The silicone rubber insulating sheath has excellent thermal conductivity, which can effectively reduce the temperature of the busbar during operation, increase the current carrying capacity of the busbar, and solve the aging and cracking of the heat shrinkable sleeve due to the rise of the busbar temperature. problem.

(4) The construction is convenient and fast. The time in the power system construction process is very limited, which requires simple and fast construction work. The silicone rubber insulating sheath and the busbars are bonded with silicone rubber adhesive. The silicone rubber adhesive is applied by brushing, and then the silicone rubber insulating sheath can be directly covered. No special tools are required. Generally, one person The above construction operations can be completed. In addition, the insulating protective covering layer can be manufactured in the factory, and can be constructed on site, which saves costs and improves sealing performance.

(5) The silicone rubber insulating sheath has strong insulation. When the power equipment is running, arc is unavoidable in the rectifier cabinet. Due to the excellent insulation of the silicone rubber insulating sheath, it can greatly improve the insulation withstand voltage level of the busbar in the power distribution cabinet, and reduce the air breakdown and insulation drop. The short-circuit failure of the power grid can avoid the short-circuit accident between the busbars caused by the climbing of small animals and ensure the safe operation of power grid equipment.

4. Attention in use

(1) There are special-shaped components in the 10kV bus (busbar), connecting busbar, and switch cabinet, and it is necessary to solve and formulate insulation treatment methods for the special-shaped components;

(2) As a new type of product, silicone rubber insulating sheath has no relevant maintenance standards and process standards.

(3) During the manufacture, application and operation of silicone rubber, it is strictly forbidden to contaminate the surface with oil, especially those using dodecylbenzene. If there is oil, it should be wiped clean in time, otherwise it will affect the quality of the surface of the silicone rubber. .

5. Conclusion

With the needs of power development, in-depth research on the insulation properties of silicone rubber, further improving the comprehensive performance of silicone rubber insulation materials, and solving related technical problems will better guide the design, construction and operation of power equipment, which has far-reaching significance .