In recent years, with the development of urban construction, power transformers installed in buildings, low-rise railways, airports and other places with high fire protection requirements require the use of oil-free equipment. In order to meet the fire requirements, non-oil-filled transformers came into being. Early working parts, such as windings and iron cores, were exposed to air. In order to solve the problem that the fiber insulation material of the transformer winding reduces the insulation level due to moisture absorption, the transformer winding should be immersed in novolac and dried. In order to further improverice cooker transformerThe insulation level and solve the heat dissipation problem in its work, the winding form needs to increase the distance between the layers and the number of winding turns as the duct. Where necessary, a blower shall be provided for forced convection air cooling.
Nevertheless, the userice cooker transformerThe installation site must have good contact. If there is a ventilation system, the relative humidity of the air should not exceed 70%, and the ambient temperature should not exceed 40°C. Early dry-type transformers brought great inconvenience to operation and limited the development of high-power transformers. Voltage large capacity transformer products. At present, this kind of air-cooled dry-type transformer is only used for small products with special voltage lower than 500V.
Due to the market demand for disaster prevention transformers, in the 1960 s, the German TU company developed a dry-type transformer, which is made of high and low voltage winding steel wire and glass fiber reinforced epoxy resin. Epoxy resin has flame retardancy and self-extinguishing properties, greatly improvingrice cooker transformerdisaster prevention capacity. After the product was put on the market, it aroused great interest and was welcomed by users. Subsequently, many countries in the world have also developed or introduced patented technology, epoxy resin castingrice cooker transformerAlmost occupy the entire dry-type transformer market. China began to introduce epoxy resin cast dry-type transformer technology in 1979 to produce epoxy resin cast transformers.