(1) Core Manufacturing Technology
Enterprises primarily improve their core production techniques by upgrading their shearing equipment. Currently, core manufacturing technology has undergone the following changes:
① Adoption of the "yoke-insertion" process for core limbs. Compared to conventional methods, this process significantly reduces the time required for stacking core limbs and improves the overall quality of the core assembly. This technique is particularly well-suited for the automated production of distribution transformer cores.
② Application of multi-step lap joints. In recent years, design practices have gradually shifted from traditional single-step lap joints to multi-step lap joints in order to minimize no-load losses at the core joints. Many transformer manufacturers have adopted a localized step-lap joint approach; this not only reduces the transformer's no-load losses by over 15% but also lowers noise levels by 3% to 4%.
③ Core Laminate Processing Technology. In the early 1970s, transformer manufacturers across China utilized domestically produced silicon steel slitting lines, coupled with simple cross-cutting lines assembled from multiple individual shears.
(2) Winding Manufacturing Technology
The specialized winding assembly process was developed in the 1990s. Currently, this process has gained increasing favor among transformer manufacturers and has been rapidly adopted throughout the industry.
(3) Insulation Processing Technology
In the 1980s, as product voltage levels and capacities increased-along with the expansion of required testing protocols-insulation processing gradually evolved into a distinct discipline, separate from general metalworking. Modern gantry-type CNC machining centers have now enabled the fully automated processing of insulation components.
(4) Insulation Drying and Oil Treatment Technology
Oil-immersed transformers utilize an oil-paper insulation structure. The core processes involved are the drying treatment of the insulation materials and the vacuum dehydration of the transformer assembly. Vapor-phase drying: In the mid-1980s, Chinese transformer factories pioneered the introduction of vapor-phase drying equipment from Switzerland. In recent years, a new type of "built-in" kerosene evaporator has been developed; compared to traditional "external" evaporators, each design presents its own distinct advantages and disadvantages. Transformer oil treatment: Entering the 1980s, with the introduction of advanced oil filtration equipment from Europe and North America, China's oil purification technology achieved significant advancements. Most enterprises have now adopted the advanced vacuum spray oil purification method, which demonstrates exceptional efficacy in removing impurities and moisture.
(5) Energy-Saving Technologies
Tracing the evolutionary trajectory of energy-saving transformer technologies, transformers have undergone a series of generational upgrades-spanning the S6, S7, S9, and S11 series. Currently, the S9 series of energy-efficient products constitutes the market mainstream, while the market share for the S11 series is steadily expanding. During the market rollout of the S11 series, its selling price averaged 14.2% higher than that of the S9 series; consequently, price remains a primary factor influencing the widespread adoption and promotion of S11 transformers. Although the new S9 products currently dominate the market, the demand for S11-type products is gradually rising alongside economic growth-particularly among users within rural power grids, where transformer load factors tend to be relatively low. The S11-type stacked-core transformer was designed and developed based on the mature technological foundation of the new S9 series; while maintaining product reliability, it delivers significantly enhanced performance metrics. Compared to traditional stacked-lamination transformers, the S11 wound-core distribution transformer offers distinct advantages, including raw material conservation, energy efficiency, improved power supply quality, reduced noise levels, and a high degree of manufacturing automation.
