Silicone rubber is divided into high temperature vulcanization (HTV) and room temperature vulcanization (RTV). The latter is also 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 adhesive, potting material or mold. The thermal vulcanization type has the largest amount, and is also divided into methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the largest amount and product brand), and methyl vinyl phenyl silicone rubber PVMQ (low temperature resistance, radiation resistance). ), and others include eye silicone rubber, fluorosilicone rubber, etc.
As an electrical insulating material, hot vulcanized silicone rubber is mainly used to make the shed sheath of composite insulators, the jacket of zinc oxide arrester, the climbing shed (anti-fouling shed) and the high-voltage insulating parts such as the shed sheath of the wall bushing , silicone rubber jacket, arrester jacket, power jacket, drop-out arrester jacket, drop-out switch jacket, drop-out fuse jacket, transformer jacket, disconnect switch sheath, protective cover.
1. Application of silicone rubber jacket
According to the data, the silicone rubber composite jacket has been widely used in my country's power transmission and transformation equipment manufacturing industry in recent years, such as zinc oxide arresters of 330kV and below, pillar insulators of 252kV and below, current transformers of 126kV and below, and suspension insulators. And in many aspects, the performance is better than that of the electric porcelain bushing, which greatly promotes the development of the electric power industry and improves the safety of electricity use.
Main advantages
(1) The silicone rubber jacket is formed by high temperature injection molding, which is not broken, the interface quality is reliable, the core body is protected, and the required creepage distance is provided. The use of silicone rubber insulators in 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 the pollution flashover resistance of the insulation. Operating in a harsh environment, the hydrophobicity of the silicone rubber surface can be temporarily weakened or lost due to partial discharge in the high-intensity field area and contamination on the surface of the umbrella cover, but the hydrophobicity of the surface can be automatically restored after a few hours.
(3) The silicone rubber composite sleeve has excellent high and low temperature resistance (working temperature is -50 degree to 150 degree ), aging resistance (resistance to ultraviolet radiation and ozone), and tracking resistance.
(4) The composite casing has excellent electrical insulation properties. The creepage distance of the composite insulating bushing can be reduced by 1/4 compared with the creepage distance required for the same level of porcelain insulation, and on products of the same height, the creepage distance of the composite bushing can be much higher than that of the porcelain insulating bushing. .
(5) The composite bushing is light in weight, easy to transport, convenient for installation and construction, etc. At the same time, it can reduce the quality of high-voltage circuit breaker and other components.
(6) The mechanical properties are stable and reliable. There is no dangerous accident such as rupture and explosion, which better protects other operating equipment.
(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 Insulating jacket
With the development of industry and the increasingly serious environmental pollution, the insulation protection of power system substation, especially the insulation protection of old substations, is becoming more and more important. In substations, pollution flashovers, condensation flashovers, ice-covered trips, short-circuits of small animals, and personal casualties caused by bare busbars often occur.
The use of heat-shrinkable materials for comprehensive insulation protection of substations can reduce the occurrence of such accidents, improve the reliability of power supply systems, and is of great significance to the safe operation of power systems. However, when heat-shrinkable materials are used to transform power system equipment, it is necessary to carry out It is extremely inconvenient to dismantle the equipment when the power is cut off, and the insulating sleeve is not tightly connected to the special-shaped joint, so it is difficult to be fully enclosed, and as the temperature of the busbar increases, its service life will be severely attenuated and decreased. Due to the serious 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 environment is prone to aging, deformation and damage, and has a short service life. It is inconvenient to replace the casing, and the cost is high.
In order to better eliminate the above deficiencies, silicone rubber insulating sheaths have begun to be deeply applied to substations. In 2008, Tangshan Power Supply Company carried out full insulation treatment of dry-type reactors with silicone rubber, and the insulation effect is excellent. Deal with the dry-type air-core reactor equipment in transit, so as to prevent small animals from entering the equipment interval and cause the reactor to be damaged.
The artificial short-circuit test proves that the reactor can effectively avoid the interphase short-circuit fire accident caused by the climbing of small animals after full insulation treatment.
3. Characteristics of silicone Rubber Insulating jacket
(1) The silicone rubber insulating coating has strong flame retardancy. Insulation materials for power equipment are required to be flame retardant. This product is mainly composed of rubber-plastic blended polymers, and flame retardants with excellent performance are added to make its flame retardancy reach FV-0 level, which meets the flame retardant requirements of power systems.
2. Good aging resistance of silicone rubber insulating jacket. The service life of the silicone rubber insulating sheath can reach more than 20 years, which greatly reduces the cost of recoating, the time of power outage and the economic loss caused by the outage.
(3) The silicone rubber insulating sheath has excellent thermal conductivity, which can effectively reduce the temperature of the busbar during operation, improve 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.
(4) The construction is convenient and fast. The time during the construction of the power system is very limited, which requires the construction work to be simple and fast. The silicone rubber insulating sheath and the busbar are bonded with a 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. The above construction operations can be completed. In addition, the insulating protective covering layer can be manufactured in a factory or constructed on site, thereby saving costs and improving sealing performance.
5. Good insulation of silicone rubber insulating jacket. When the power equipment is running, arcs are inevitably generated in the rectifier cabinet. Because the silicone rubber insulating sheath has excellent insulation, it can greatly improve the insulation withstand voltage level of the busbar in the power distribution cabinet and reduce the air shock. Short-circuit faults caused by wear, insulation and voltage reduction, so as to avoid short-circuit accidents between busbars caused by small animals climbing, and ensure the safe operation of power grid equipment.
4. Notices for use
(1) There are special-shaped components in the 10kV busbar, connecting busbar, switchgear, and it is necessary to solve and formulate the insulation treatment method for the special-shaped components;
(2) As a new type of product, silicone rubber insulating sheath has no relevant maintenance standards and process standards for the time being.
(3) During the manufacture, application and operation of silicone rubber, it is strictly forbidden to contaminate oil on it, especially those using dodecylbenzene. If there is oil contamination, it should be wiped clean in time, otherwise it will affect the quality of the silicone rubber surface.
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 its related technical problems will better guide the design, construction and operation of power equipment, which has far-reaching significance.