20kV Class Oil Immersed Transformer S11

ZTELEC Oil-Immersed Transformer | High-Efficiency Power Distribution Solution

ZTELEC YuGuang Electric Technology (Zhengzhou) Co., Ltd — Oil-Immersed Transformer

The oil-immersed transformer is a widely used power equipment designed with a structure similar to conventional transformers. Its defining feature is the oil-immersed insulation system, which effectively reduces heat buildup and enhances long-term reliability. This makes it an essential component in modern power distribution networks and substations.

Core Structure and Working Principle

An oil-immersed transformer consists of three key elements: the core, the winding, and the bushing. The iron core provides a magnetic path, while the windings generate the magnetic field and are insulated using high-quality barriers and shields. The insulation thickness increases with voltage levels to ensure operational safety. Bushings serve as the interface connecting the windings to the substation.

During operation, both the core and windings are fully immersed in insulating oil. The oil circulates naturally through the internal channels and around the core assembly, providing efficient cooling and electrical insulation. Smaller-capacity units dissipate heat through the tank surface, while larger-capacity models rely on air-cooled radiators.

Applications of Oil-Immersed Transformers

Oil-immersed transformers can be installed on the ground, poles, or platforms, making them suitable for a wide range of outdoor environments. They deliver outstanding performance in power transmission networks, distribution systems, renewable energy installations, and small to medium industrial operations.

Thanks to their high capacity and excellent efficiency, these transformers help reduce power loss, save energy, and lower operational costs. The insulating oil enhances cooling performance, protects the internal components, and improves transformer longevity.

Main Features

The fully sealed oil-immersed transformer uses a complete oil-filled enclosure. The corrugated tank design accommodates oil expansion through its own elasticity, eliminating the need for an oil conservator and providing a maintenance-free structure widely adopted in power distribution systems.

High-quality cold-rolled oriented silicon steel sheets are used in the iron core, manufactured using advanced automatic cross-cutting and step-lap technology. This optimizes magnetic flux distribution, reduces vibration, and minimizes noise and core loss.

The coils are wound with high-strength enameled or paper-covered wires in a cylindrical or cake-type structure. This ensures balanced ampere-turn distribution, enhanced insulation strength, and strong resistance to short-circuit forces.

The transformer body adopts an anti-loosening mechanical structure with locknuts and a non-hanging core design to ensure stability during long-distance transportation.

The corrugated oil tank replaces the need for an oil conservator. Its ability to expand and contract with oil volume changes isolates the internal components from external moisture and air, slowing insulation aging and significantly improving reliability.

The transformer is equipped with a remote monitoring thermometer and a pressure relief valve, providing enhanced operational safety and real-time status monitoring capability.

Performance parameters