10kV Class Oil Immersed Transformer S11

Structure and Working Principle of Oil-Immersed Transformer | Features, Standards & Applications

An oil-immersed transformer is a widely used power device in transmission and distribution networks. Classified by its insulation structure, it features oil-immersed coils that effectively reduce heat and enhance electrical insulation. Its design ensures long-term reliability and stability in industrial and utility applications.

Basic Structural Components

The main components of an oil-immersed transformer include the core, windings, and bushings. The magnetic core provides a pathway for magnetic flux, while the windings—made of insulated conductor coils—generate electromagnetic induction. The thickness of the winding insulation increases proportionally with the rated voltage. Bushings serve as the interface connecting internal windings to external power systems such as substations.

Working Principle of Oil-Immersed Transformers

In operation, the core and windings are fully immersed in insulating oil, which provides both cooling and electrical insulation. The oil circulates naturally through convection, flowing around the windings and core. For lower power ratings, heat is dissipated through the tank wall. For larger transformers, cooling is enhanced using air-cooled radiators to maintain stable operating temperatures.

Purpose and Application Fields

Oil-immersed transformers are designed for ground-mounted, pedestal-mounted, or pole-mounted outdoor installations. They offer excellent performance across power distribution networks, renewable energy systems, small industrial facilities, and regional substations. Their high capacity helps minimize energy loss, reduce operational costs, and ensure stable power delivery.

The insulating oil also acts as a coolant, improving the durability of the internal windings and enhancing the overall electrical performance of the transformer.

Main Features

Enhanced Short-Circuit Strength: The three-phase oil-immersed transformers manufactured by our company adopt a new insulation structure to improve short-circuit resilience.

Premium Materials: The magnetic core is made of high-quality cold-rolled silicon steel sheets. The winding uses multilayer cylindrical or foil structures with anti-loosening fasteners to ensure long-term stability.

High Efficiency & Low Loss: Optimized electromagnetic design significantly reduces losses, lowers energy consumption, and minimizes operating costs. It is recognized as a national high-tech energy-efficient product.

Applicable Standards

GBT 6451-2015: Technical parameters and requirements of oil-immersed power transformers

GB 1094.1-2013: Power transformers – Part 1: General rules

GB 1094.2-2013: Power transformers – Part 2: Temperature rise

GB 1094.5-2008: Power transformers – Part 5: Ability to withstand short circuit

GBT 1094.7-2008: Load guidelines for oil-immersed power transformers

Regular Service Conditions

Elevation is below 1000 m above sea level.

Ambient temperature conditions:

Maximum ambient temperature: +40°C

Maximum daily average temperature: +20°C

Minimum outdoor ambient temperature: –25°C

Performance parameters