Dry-Type Transformer: Oil-Free Safety for Diverse Applications

Dry-type transformers are transformers in which the core and windings are not immersed in insulating liquid. With the core advantages of being oil-free, fire-resistant and eco-friendly, they have become indispensable and important equipment in modern power distribution systems. Their main insulation media are solid materials such as air and epoxy resin, eliminating the risks of fire and leakage associated with oil-immersed transformers.

Structurally, dry-type transformers mainly consist of a silicon steel core and epoxy resin cast coils. Insulation cylinders are placed between the high-voltage and low-voltage coils to enhance electrical insulation, and all fasteners for component connections are locking-proof. The core windings are categorized into concentric and interleaved types, with the concentric type widely used due to its simple manufacturing. Based on different insulation methods, common dry-type transformers are mainly divided into two categories: resin-encapsulated dry-type transformers and impregnated dry-type transformers. Resin-encapsulated dry-type transformers feature high mechanical strength, strong short-circuit withstand capability, excellent moisture and corrosion resistance, low partial discharge and long service life. Impregnated dry-type transformers boast a high insulation heat resistance class, superior fire performance, and do not produce dense smoke when burned at high temperatures.

Their core characteristics are prominent:First, safety and environmental friendliness: no toxic gas emissions, flame-retardant and self-extinguishing, with no requirement for separate fire protection spacing.Second, convenient operation and maintenance: low losses, low operating noise, eliminating maintenance tasks such as regular oil sample testing, achieving essentially maintenance-free operation.Third, strong adaptability: small size, light weight, easy installation and commissioning, capable of operating in harsh environments such as high humidity. Equipped with a comprehensive temperature monitoring and protection system, it can automatically monitor winding temperature and realize functions including fan start/stop, alarm and tripping.Fourth, energy efficiency: capable of long-term rated operation under natural air cooling, and output capacity can be increased by 50% under forced air cooling, flexibly meeting short-term overload demands.

In terms of application scenarios, dry-type transformers are mainly suitable for important places with high fire protection requirements and dense personnel, such as high-rise buildings, underground structures, airports, theaters, subways, commercial centers, and communication & information centers. They are also widely used in fire and explosion-proof locations in large industrial and mining areas, such as service transformers in thermal power plants, hydropower plants and nuclear power plants, as well as various scenarios where oil-immersed transformers are not applicable. Domestic independent supply of dry-type transformers has been basically achieved in national and major projects, and the proportion of 10kV dry-type transformers in distribution networks is increasing year by year.