What are the characteristics and advantages of oil-immersed transformers? Why choose an oil-immersed transformer?

Oil-immersed transformers are conventional power conversion devices that rely on insulating oil for both heat dissipation and insulation. Their core characteristic is “using oil as the medium.” Their key advantages include suitability for large-capacity applications, low cost, and high stability. The primary reason for choosing them lies in their practical value in outdoor and heavy-industrial environments.

I. Core Features

The core medium is insulating oil: The transformer interior is filled with specialized insulating oil, which not only helps dissipate heat from the iron core and coils but also isolates electrical current and prevents short circuits.

Equipped with a sealed oil tank: All core components are enclosed within a sealed oil tank, and the exterior is fitted with cooling tubes (or fins) to facilitate the circulation and cooling of the insulating oil.

Suitable for high-capacity applications: The structural design is optimized for increased capacity, easily accommodating several thousand kilovolt-amperes—unlike dry-type transformers, which are limited by capacity.

Oil leakage and moisture prevention are essential: Although the fuel tank has a sealed structure, its sealing performance should be closely monitored during long-term use to prevent oil leaks and contamination. Additionally, it’s important to protect the tank from rain and moisture.

II. Key Advantages

High thermal efficiency: Insulating oil has significantly better thermal conductivity than air, enabling it to quickly dissipate the heat generated during equipment operation. This allows the equipment to operate at full load for extended periods without easily experiencing overheating failures.

More cost-effective: The manufacturing process is relatively mature, and the material and production barriers are lower. At the same capacity, the price is 20% to 50% lower than that of dry-type transformers, and large-scale adoption can further reduce costs.

Wide capacity coverage: We can manufacture equipment ranging from several hundred kilovolt-amperes to tens of thousands of kilovolt-amperes, meeting the heavy-load power supply demands of large-scale factories, urban distribution networks, and other similar applications. This makes our equipment the mainstay for high-capacity power supply.

High stability: The sealed structure effectively blocks external factors such as dust and moisture, and the internal components are resistant to aging. With regular maintenance, the service life can reach 20 to 30 years—far longer than that of some dry-type transformers.

Low maintenance costs: Apart from regularly checking the quality of the insulating oil (to ensure it hasn’t deteriorated or exceeded the allowable moisture content) and replacing seals, virtually no additional maintenance is required on a daily basis, resulting in minimal operation and maintenance workload.

III. The Core Reasons for Choosing Oil-Immersed Transformers

Outdoor open-space scenarios: In open areas such as wilderness, suburbs, and industrial parks, there’s no need to worry about fire risks (as they’re kept away from flammable materials), and there’s ample space for installing fuel tanks and cooling systems, making these setups highly adaptable.

High-capacity power supply requirements: In scenarios such as large-scale factories, mines, hydropower stations, and urban main distribution networks that demand high-power supply, only oil-immersed transformers can meet the requirements of "high capacity + long-term stable operation."

Cost-control requirements: For projects with limited budgets and a focus on cost-effectiveness, oil-immersed transformers offer lower procurement and operation & maintenance costs under the same power supply capacity, thereby reducing overall investment in power infrastructure.

Adaptation to Harsh Environments: In high-temperature and dusty environments, sealed tanks protect internal components, and the stability of the insulating oil ensures that the equipment operates reliably—making it more durable than equipment with open-air cooling systems.

IV. Supplementary Notes 

Although oil-immersed transformers offer certain advantages, they also have limitations: there is a risk of oil leakage and contamination, so they cannot be used indoors or in areas with high population density (such as residential communities or shopping malls) or in flammable and explosive environments. They must be installed separately in transformer rooms or outdoor racks, occupying more space than dry-type transformers. However, in scenarios where they are appropriately suited, these limitations can be mitigated through standardized installation practices—such as setting up oil-containment pits—without compromising their core value.