Since 1979, China's transformer industry has set a new loss reduction target for small and medium-sized transformers, and started to design energy-saving and low-loss transformers. The joint design was completed in 1981, and the prototype was made in 1982. The no-load loss of 10kV class SL7 transformer shall be reduced by about 40%, and the load loss shall be reduced by more than 10%, which is called low voltage power transformer
or energy-saving transformer
Lower loss are the main measures of the core material is cold rolled grain oriented silicon steel sheet, silicon steel sheet performance is good, the unit loss is small, and improve core production process, which uses 45 ℃ by core juncture, thus greatly reduce no-load current, core not punching at the same time, use sticky tape binding structure, improve the utilization rate of core and silicon steel sheet don't have to do paint processing, use of silicon steel sheet itself insulation insulation membrane, reduce the gap between the silicon steel sheet. When the silicon steel sheet is sheared, burr is strictly avoided to make the core seam smooth and tight, so as to achieve the goal of reducing no-load loss and no-load current. As the utilization rate of the core is improved, the volume of the core is reduced and the coil is reduced, thus the load loss is reduced.
With the continuous improvement of the manufacturing process of low voltage power transformer, the transformer performance parameter standard is constantly refreshed. At present, the implementation is the newly issued GB/ t6451-2008 "technical parameters and requirements of oil-immersed power transformer", which is the release of the technical standard, that is to announce the formal completion of the transition from S7 to S9 of the 6, 10/kV distribution transformer technical standard, and the subsequent prohibition of production and sales of S7 and S8.