The Birth Of New Dry Type Transformers On Production Development
With the development of urban construction in recent years, power transformers installed in buildings, low-speed railways, airports and other places with high requirements for fire protection require the use of oil-free equipment. In order to meet the fire protection requirements, non-oil-filled transformers - dry-type transformers came into being. The working parts of the early dry-type transformers, such as windings and iron cores, were exposed in the air. In order to solve the problem that the fibrous insulating materials of the transformer windings reduce the insulation level due to moisture absorption, the transformer windings should be soaked and dried in phenolic varnish as a whole. In order to further improve the insulation level of the transformer and solve the problem of heat dissipation in the operation of the transformer, the winding form of the transformer winding needs to increase the distance between layers and turns of the winding as an air duct. When necessary, the transformer should also be equipped with a blower to force convection air cooling to dissipate heat.
Nevertheless, it is also required that the transformer installation site must have good links when used. If there is a ventilation system, the relative humidity of the air should not exceed 70%, the ambient temperature should not exceed 40 ℃, and so on. The early dry-type transformers brought great inconvenience to the operation work and restricted the development of high-voltage and large-capacity transformer products. At present, this air-cooled dry-type transformer is only used in small transformers with a voltage level below 500V and special purposes.
Due to the market demand for disaster-proof transformers, in the 1960s, German TU company developed a dry-type transformer with high and low voltage windings of steel wires and glass fiber reinforced epoxy resin. Epoxy resin has the characteristics of flame retardancy and self-extinguishing, which greatly improves the disaster prevention ability of transformers. After the product was put on the market, it aroused great interest of users and was welcomed by users. Subsequently, many countries in the world have successively developed or introduced patented technology for production, and epoxy resin cast dry-type transformers have almost occupied the entire dry-type transformer market. my country began to introduce epoxy resin casting dry-type transformer technology in 1979 to produce epoxy resin casting transformers.
