Environmental Protection And Development Trend Of High Voltage Electrical Appliances Manufacturers

“Kyoto Protocol” set forth in one of the six greenhouse gases sulfur hexafluoride (SF6) gas emissions into the atmosphere mainly through the power transmission and distribution equipment, especially high voltage switchgear, transformers, transformers and gas insulated transmission pipelines and other products are in the experimental research, manufacturing, transportation and operation and maintenance generated in the process.

SF6 gas in high voltage electrical products account for about the application of SF6 gas applications, 80%, while the SF6 gas switch device is currently leading the field of high voltage switch products, but also ultra high pressure and special high voltage switchgear applications and development of the main directions, so understanding of the environment changes and trends in the protection and control emissions of SF6 gas into the atmosphere to study the SF6 gas in the power switching devices for power switching applications of great significance to the development of equipment.

Atmospheric environmental protection situation December 11, 1997, 149 countries and regions, representatives, adopted the “Kyoto Protocol” provides for six greenhouse gases (GHG), which are: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons , sulfur hexafluoride. This Protocol was February 16, 2005 came into effect, which provides that during the period from 2008 to 2012, the main industrial greenhouse gas emissions by developed countries in 1990 on the basis of an average of 5.2%, of which the EU will be six kinds of greenhouse gases emission reductions of 8%, 7% reduction of United States, and Japan 6%, Canada 6% reduction, Eastern European countries, reduction of 5% to 8%; New Zealand, Russia and Ukraine do not have to cut emissions can be stabilized at 1990 levels; Protocol while allowing Ireland, Australia and Norway, respectively, compared with 1990 emissions increased by 10%, 8%, 1%; developing countries have emission reduction obligations.

China on May 29, 1998 signed the “Kyoto Protocol”, August 30, 2002 formally approved the “Kyoto Protocol”, although China has not provided herein emission reduction obligations, but experts predict that China’s C02 emissions will soon overtake the U.S. as the world’s first one, when the time will inevitably be to fulfill the “Kyoto Protocol” emission reduction provisions. In the “Eleventh Five Year” period made it clear that to fulfill the “Kyoto Protocol” obligation, so SF6 gas in other appliances, such as transformers, transformers, load switches, transmission pipelines, etc. The application and development of SF6 gas into the atmosphere should be considered the emissions, the study of more environment friendly enterprises to adapt to the economic development programs.

Characteristics of SF6 gas The study found that at atmospheric pressure under the uniform electric field strength of SF6 gas insulated air three times, although less than the insulating oil and the high vacuum state, but the increase of SF6 gas pressure, the insulation strength will be higher than that of insulating oil, and high vacuum. With air contrast study also found that, in the arc discharge cases, the air temperature gradient is relatively small, rough arc, SF6 gas, the overall temperature is lower, mainly concentrated in high temperature parts of the arc. Therefore, SF6 gas in the arc cut off very quickly after the cooling, insulation and resilience of good air about 100 times. SF6 gas on the environmental impact of SF6 gas molecular weight is 146, the air density is about 5 times. SF6 gases in the atmosphere to survive life is 3200 years. Therefore, SF6 gas is a very strong greenhouse gases. SF6 is a greenhouse gas CO2 to the atmosphere of 23900 times.

In addition, SF6 gas switch device in the process of breaking currents will produce arc, the arc will SF6 gas under high temperature decomposition, but also will produce metal vapor arc of contact, due to the presence of water in interrupter will be broken down, decomposed material will produce secondary reaction to form HF, S02, SOF2, SOF4, SO2F4 and other harmful substances. These substances will be corrosive internal metal components, if these substances emitted into the atmosphere on the person’s body can cause injury and stimulation.

Application and Development of SF6 Gas In 1953, the United States first SF6 gas used in 115kV load switch devices, in 1958, Westinghouse created a tank along the lines of the compressed air circuit breaker 220kV double pressure type SF6 circuit breaker. The principle of this circuit breaker through the SF6 gas from compressed gas cylinders (1.5MPa) the flow of low pressure gas chamber (0.3MPa) and the cooling breaking arc. With this double pyramid structure, also developed the ceramic pole SF6 circuit breaker. Followed by Europe and Japan on the SF6 gas switch device manufacturing technology research has made great progress and development. The emergence of SF6 circuit breaker is a high voltage power system circuit breaking in from the oil circuit breakers, compressed air circuit breaker technology has begun a series of technological advances of recent results.

It is with the oil circuit breakers, compressed air circuit breaker advantage is that a single fracture compared with the high voltage, arc quenching ability, breaking current, circuit breaker, light weight, operate small power, high reliability, low maintenance, avoiding the oil circuit breakers prone to fire breathing, fuel injection and other undesirable phenomena, in addition to structural diversification interrupter chamber (variable air pressure to open away from the ceremony, scheduled to open away from the pressure air type, self energy type and mixed type) and so on.

SF6 gas switch equipment, the continuous development of the structure of different types of products, such as the tank and ceramic column SF6 circuit breakers, GIS, HGIS, compound and so on. Including GIS, HGIS, and complex type can have a wide variety of product layout, these features allow the user in the design of power system substation, it can be selected according to different situations. Since 1979, China began to introduce, or with foreign countries to develop 72.5kV ~ 550kVSF6 high voltage switchgear, after decades of development, SF6 electrical appliances manufacturing enterprises increased year by year. Currently, domestic enterprises can produce medium voltage (12kV), high voltage (40.5kV ~ 252kV), EHV (363kV ~ 550kV), and ultra high voltage (800kV 1100kV) SF6 high voltage switchgear.

Because SF6 gas has excellent insulating and arc quenching performance of the electrical installations to achieve the economic oriented, low maintenance oriented operation and space saving, SF6 gas has also begun to high voltage transmission and distribution equipment in the transformer, transmission pipelines and transformer areas such as application development. At present, Japan is the country with the largest production of SF6 transformers, Mitsubishi, Toshiba, Hitachi, Fujitsu can produce.

SF6 transformers can be done at present levels of 500kV and 300MVA. I also have the domestic production 10kVSF6 transformers, some of them with foreign companies set up a joint venture and have the 110kV and above, SF6 transformer manufacturing capacity. In addition to high voltage SF6 gas circuit breaker in the transmission and distribution equipment, GIS, load switches, transformers, transformers and gas transmission pipeline is applied, there are a small part of the SF6 gas is used in sports shoes, scuba diving with breathing apparatus, medical field, thermal insulation glass windows, casting technology used to protect the gas, pneumatic tires, and military and other non electrical equipment.

As the world power industry development, especially in recent years, China’s sustained and rapid development of power industry in order to meet electricity demand, steady increase in grid construction and renovation, making the number of high voltage power transmission and transformation equipment, demand for an unprecedented growth, increased SF6 gas usage, but also an increase of SF6 gas into the atmosphere emissions. SF6 gas for electricity can be seen that the contribution of the building the greater the contribution to atmospheric greenhouse effect is also increasing.

SF6 gas emissions into the atmosphere means SF6 gas emissions to the atmosphere mainly through the power transmission and transformation equipment, pressure testing of new products, capacity, breaking test, factory test, transfer of equipment, transportation, installation, operation, equipment maintenance and so on. The United States during the period from 1998 to 2002 the production and processing of high voltage circuit breakers installed in the SF6 gas leakage rate were investigated. As a result, 10% of the circuit breaker leak may exist. Leakage reason: 73% occurred in the gas installation, 21% is due to worn and damaged casing, and 6% is due to leakage of gas containers.

SF6 gas emission reduction measures and development trend of SF6 electrical Direction of development of high voltage electrical products, especially the SF6 high voltage electrical products, should be to reduce emissions of SF6 gas to the atmosphere, the direction of the development of specific measures include: 1, raising the technological level of manufacturing process equipment, reducing the leakage rate of SF6 electrical equipment. 2, to promote the miniaturization of SF6 electrical equipment and reduce the volume of SF6 electrical equipment in order to reduce the use of SF6 gas. In order to significantly advance the miniaturization of GIS and non SF6 technology, Mitsubishi Electric Co., Ltd. to SF6 gas and thick film dielectric coated electrode composite insulation system as an object to study the insulating properties of high pressure areas. By using thick film dielectric coated together, can achieve curb the size of the metal electrode effect caused by the breakdown electric field decline; can reduce the electrode space, the largest gas field, to achieve device miniaturization. As far as possible a high degree of integration, layout and flexible composite electrical appliances or HGIS.

3, developing low pressure of the SF6 switchgear and SF6 gas mixture of electrical equipment. Countries in the world has been studying alternatives to SF6 gas for many years abroad on a variety of mixed gases (such as SF6 N2, SF6 CO2, SF6 CF4) in the PD characteristics of insulation breakdown characteristics of the study found that for the liquefaction temperatures were particularly low, non toxic and stable N2 gas, mixed with 20% of the SF6 gas and the non uniform electric field in the partial discharge starting voltage (PDIV) and dielectric breakdown voltage (BDV) has increased the possibility of, and, also found in high gas pressure, can get 100% SF6 gas with roughly the same insulating properties. So SF6 N2 is considered the preferred alternative to SF6 gas. At present, the world’s first hybrid gas insulated high voltage lines N2 SF6 in Geneva completed. ABB has developed LTB 72.5 kV a 145kV GCB and HPL72.5 300B1 type GCB can be used either pure SF6 gas can also be used SF6 N2 gas mixture. When using SF6 N2 mixed gas, at 20 ? Rated air pressure 0.7MPa (absolute), it can be used in 50 ?, while in pure SF6 gas 0.5MPa (absolute), the only for 40 ?. Toshiba also N2 SF6 mixed gas circuit breaker is studied.

4, in the equipment manufacturing and equipment maintenance during the use of advanced SF6 gas recovery unit, the recovery through a variety of filters to remove the SF6 gas in the water, oils, dust, and other elements resultant decomposition. Achieve SF6 gas recycling.

5, in the medium voltage (12kV 40.5kV) areas, use of non electrical SF6 and vacuum switchgear, high voltage (40.5kV ~ 252kV) fields to the special high voltage (800kV 1100kV) areas, to develop a vacuum circuit breaker (VCB), to upgrade technology and equipment to reduce manufacturing costs VCB, vacuum switchgear to achieve a large number of high pressure area so that active rejection vacuum circuit breaker (VCB) of high voltage oriented research work, to achieve high voltage of VCB and EHV oriented.

6, protection of atmospheric environment, and foster awareness of emission reduction. Japan is the use of SF6 gas more countries, in order to implement the “Kyoto Protocol” on SF6 gas emission reduction obligations, NEC Business Association, the Japanese electric industry to achieve this goal will be taken positive action. Japan SF6 gas reduction measures is to establish a check curb emissions, to replace SF6 gas insulated equipment curb emissions, recycling system, and has taken action to improve the SF6 gas management system. Germany’s high voltage switching equipment industry is also very well developed. Annual use of SF6 gas is about 1000t. In order to achieve reduction of SF6 gas emission targets, October 19, 2005, the power to run industry and electrical equipment manufacturing industry associations and Solvay Fluor GmbH (SF6 gas manufacturing) companies and the German Environment, Nature Conservation and Nuclear Reactor Safety for further provisions of the Federal Ministry of have reached a consensus on their own obligations.

7, to carry out the Clean Development Mechanism (CDM), to achieve reduction of SF6 gas.

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