Power transformers are one of the important equipment in the system of transmission, transmission, change and distribution. Its performance and quality are directly related to the reliability and operation efficiency of power system operation.
First, the power transformer varieties
(1) distribution transformers China's small and medium-sized distribution transformers were initially insulated oil for the development of insulating media; into the 20th century, 90 years, dry-type transformers in China have a very rapid development.
(1) oil-immersed distribution transformers S9 series distribution transformers, S11 series distribution transformers, roll core distribution transformers, amorphous alloy core transformers. In order to make the operation of the transformer more complete, reliable, easier maintenance, more widely meet the needs of users, in recent years, oil-immersed transformer with a sealed structure, the transformer oil and the surrounding air completely isolated, thereby improving the reliability of the transformer. At present, the main sealed form of air-sealed, nitrogen-sealed and full oil-filled seal type. The full oil-filled sealed transformer market share is getting higher and higher, it changes in the volume of insulating oil, by the corrugated tank wall or expansion of the radiator to compensate for the elastic deformation.
(2) <0> <0> Because of the simple structure, easy maintenance, and fire, flame and other characteristics, China from the late 1950s that began production, but nearly 10 years before the start of mass production. There are many types of dry-type transformers, mainly impregnated insulated dry-type transformers and epoxy-insulated dry-type transformers.
(2) box-type transformer box-type transformer with a small footprint, can reach the load center, reduce line losses, improve power supply quality, flexible selection, beautiful appearance and other characteristics, the current 10Kv, 35kV power grid in a large number of applications. China's current use of box-type transformers, mainly Continental box change and American box change, the former transformer as a separate component, that is, high-voltage power part, distribution transformers, low-voltage power distribution part of the three. The latter structure is divided into two parts, the front part of the wiring cabinet, the rear part of the transformer fuel tank, winding, core, high pressure load switch, plug-in fuse, backup current limiting fuse and other components are placed in the tank body. At present, some manufacturers have moved the coil core transformer to the box transformer, so that the volume and quality of the box transformer have been reduced to achieve a high efficiency, energy saving and low noise level.
(C) high-voltage, ultra-high voltage power transformer At present, China has a 110kV, 220kV, 330kV and 500kV high pressure, high pressure transformer production capacity. Ultra-high voltage transformer insulation medium is still the main insulating oil, according to the needs of power grid development, transformer production technology is constantly improving. SF6 gas insulation high voltage, ultra high voltage transformer is being researched and developed.
Second, the level of manufacturing Overall, China's power transformer technology in the international 20th century, the level of the early 90s, a small amount of the world in the late 1990s the level of the 1990s, compared with foreign advanced countries, there are still some gaps.
1, the core material In the 20th century, 70 years, Wuhan Iron and Steel Company in the introduction of digestion and absorption of Japanese cold-rolled silicon steel sheet manufacturing technology to produce cold-rolled silicon steel sheet on the basis of the 20th century, 90 years and the introduction of Japan's high magnetic grain to cold rolled silicon steel (HI-B) manufacturing technology, to create a better energy-saving power transformer core material.
In the development of distribution transformer core with amorphous alloy materials, China in the early 1990s by the original mechanical department, the original metallurgical department, the original power department, the State Planning Commission, the State Economic and Trade Commission, the former National Science and Technology Commission formed a special work Group, the amorphous alloy core material and amorphous alloy core transformer design and manufacturing process carried out in-depth study, the development of amorphous alloy core material basically reached the original plan indicators, and in 1994 trial out the voltage 10kV, capacity 160 ~ 500kVA distribution transformer, the power users try to show that the basic requirements to achieve practical.
2, tooling equipment Before the 1980s, China's transformer equipment, technical level, the overall is relatively low, in addition to winding equipment has a professional production plant production, the rest are mostly self-made enterprises relatively simple equipment, Only a few have a simple iron core processing line. Into the 20th century, 80 years, the transformer industry began to introduce advanced foreign key equipment, such as core slitting line, low-frequency electric drying system. To the 20th century, 90 years, due to the strong promotion of dry-type transformers, the introduction of a number of epoxy casting equipment and foil winding machine, several large-scale production plant also introduced the insulation processing center, so that China's transformer production tooling equipment level improve. Some domestic special equipment manufacturers through digestion and absorption, but also the development of vertical and horizontal production lines and other special equipment, these domestic special equipment, its function and the main technical parameters of the basic or close to the international level, to ensure that China's transformer products, improve the transformer technology Performance, improve production efficiency has played a crucial role.
3, the transformer process design for nearly 20 years, 110kV and below the voltage level of the oil-immersed transformer for a lot of optimization design, has gradually replaced the 64,73,79,86 and other standards, the current implementation of the 20th century, the late 90's 99 standard, the formation of a new series of energy-saving transformers, so that further reduce the loss, replacing the production of high energy consumption products. In 1998 the country has further clarified that the 64 series and 73 series old transformers operating in the grid must be eliminated and that the S7 transformers produced in accordance with the 1979 standard must also be discontinued. 1998 ~ 2001 urban and rural power grid construction and transformation in the implementation of the S9-type distribution transformers, in line with the 1999 national standards. Beginning in 2000, in the two network construction and transformation also used a coil core transformer.