After 1958 began to design on the basis of imitation products.Shenyang transformer factory and huatong switchgear factory successfully produced l0kV epoxy resin casting current transformer, which replaced the imitation su products.At the same time, a new series of oil - immersed insulation transformers are formed.

60 s, shenyang transformer research institute has organized many times the national unified design, completed the 0.5 kV dry-type current, voltage transformer, l0V pouring insulation current, voltage transformer, 35 kV oil-immersed unique edge current, voltage transformer, 110 kV oil-immersed insulation current, voltage transformer is a new series of design, manufacture, improve the technical performance of products, and make our products more in line with the needs of China's domestic market.

After 1970, the overall technical level of transformers in China has been greatly improved, and the varieties are increasing day by day.Shenyang transformer factory successfully trial-produced 330kV and 500kV oil-paper insulated current transformer successively.Xi 'an electric power capacitor factory also successfully trial-produced 500kV capacitive voltage transformer.

The transformer manufacturers also continue to improve and improve the products, China has the international transformer industry at that time the highest voltage level of product manufacturing capacity.

So far, China has produced various specifications of current and voltage transformers of 0.5kV ~ 500kV voltage grade, with the maximum current reaching 25000A, and formed a relatively complete series.Also designed and manufactured a variety of special purpose transformer, such as zero sequence transformer, mine transformer, if frequency transformer and so on.Xi 'an high voltage switchgear factory successfully trial-produced ~ 100kV dc current transformer in 1987, and put into operation on zhoushan dc transmission line.

With the development of urban power supply system, China began to develop the use of SF6 composite appliances.In 1973, the 110kV SF6 composite electrical appliance developed by xi 'an high voltage switchgear factory was put into operation at danjiangkou hydropower station in hubei province.The 110kV SF6 gas-insulated voltage transformer and current transformer, which are matched with the combined electrical appliances, were successfully manufactured in Shanghai transformer factory in 1979, and later 220kV SP6 gas-insulated voltage transformer and current transformer were successfully manufactured.

In order to further improve the level of transformer technology, China began to introduce advanced transformer manufacturing technology from abroad.In 1979, shenyang transformer factory introduced the manufacturing technology of 500kV oil-immersed insulated current transformer from France alstom company.In 1984, Shanghai transformer factory introduced the manufacturing technology of 72.5kv-500kv SP6 gas insulated transformer from German WB company and lokv-35kv casting insulated transformer from Swiss BBC company.After that, tianjin transformer factory, shenyang transformer factory and jiangxi transformer factory successively introduced manufacturing technology of casting insulation transformer from abroad, and Beijing transformer factory also introduced manufacturing technology of Siemens oil-immersed insulation transformer.

In 1993, Shanghai MWB transformer factory established Shanghai MWB transformer co., LTD as a joint venture with Germany MWB.The imported 72.5kv ~ 750kV independent SF6 gas transformer manufacturing technology was manufactured in China and put into operation in 1995.In 2000, Shanghai transformer factory and TRENCH group expanded the joint venture and introduced HAEFELY35kV ~ 550kV oil-insulated current transformer, oil-insulated voltage transformer, capacitive voltage transformer, casing and reactor manufacturing technology.

The introduced SF6 gas insulated current transformer and oil-immersed insulated current transformer are the newest and most advanced inverted structures in the world.The introduced SP6 gas insulated voltage transformers and oil-immersed insulated voltage transformers all adopt single-grade iron core structure, eliminating the defects of the cascade iron-core structure voltage transformers manufactured over the years.These products are advanced in technical performance and reliable in operation.

In 1964, China formulated the first professional and industrial standard of ct products, JB572 ~ 575-196&, but it was only translated based on the Soviet union's national standard, FOCT.In 1975, according to the actual technical level of the transformer industry required by the development of China's power system, the professional standard jb572-575-1964 was revised and upgraded to the national standard gbl207-1975 voltage transformer and gbl208-1975 current transformer.In 1986, the national standards were revised to gbl207-1986 voltage transformer and gbl208-1987 current transformer, equivalent to IEC standards 185 and 186.In 1997, the national standards were revised to gbl207-1997 voltage transformer and gbl208-97 current transformer, which adopted IEC standards iecl85:1987 and IEC 186:1987.

In 2002, the new standards iec60044-1 current transformer and iec60044-2 voltage transformer were revised according to the new IEC standards.The application for the new IEC standard for transformers in China was finalized in 2003 and will be issued soon.

The development process of transformer manufacturing is from sporadic manufacturing to specialized production to large-scale production. The product quality has been continuously improved over the years, and basically meets the requirements of transformer product quality classification standard.From the late 1970s to the early 1980s, the transformer industry has carried out three large-scale industrial quality inspection, which has promoted the improvement of product quality and management level of each enterprise.

In the 1990s, the international quality management requirements were stricter and more standardized, and is0-9000 quality management procedure document was promulgated and implemented.Some main manufacturers in the transformer industry have passed the certification of iso-9000 "quality management procedure file".

Scientific research work is the fundamental of product technology progress and product quality improvement in each industry.After the scale and quantity of the transformer manufacturing industry in China are formed, it is very important to carry out scientific research on the basis of the continuous improvement of the standard and the quality problems in the manufacturing and operation of the products.Shen bian has organized industry forces to study and tackle the problems of industry coexistence.Successively for casting insulation transformer partial discharge, oil-immersed transformer insulation products of partial discharge, internal moisture content, gas content and influencing factors on the quality of the transformer, such as dielectric loss by focusing on industrial strength analysis of its causes, preventing methods and explore the detection period, etc., after many years of research and practice, made a big harvest, partial discharge dedicated testing equipment is developed.Some production enterprises have used it with computer, but the precise calculation, quantitative and positioning measurement still need to be further studied.

Automatic detection, display and output devices have been widely used abroad for the error t

esting of mutual inductors.Some units have also developed automatic data display and output devices by themselves, and have professional manufacturing units, which provide suitable testing means for the construction of transformer production line.At present, these devices have been widely used in most professional transformer manufacturers.