1. What Is an Oil Immersed Transformer?
An oil immersed transformer is the most widely used power distribution transformer for outdoor substations, rural power grids, industrial parks and large-scale photovoltaic power plants. Different from cast resin dry type transformers, it adopts mineral insulating oil as the medium for heat dissipation and insulation.
The core structure consists of silicon steel sheet iron core, copper winding, transformer oil tank, heat radiating fins, conservator, explosion-proof tube and temperature monitoring components. Transformer oil fills the entire tank, which plays two core roles: isolating high and low voltage windings to avoid breakdown short circuits, and transferring the heat generated during operation to the external radiator for natural cooling.
As a mature power conversion device, oil immersed transformers convert high-voltage grid electricity (10kV/20kV) into low-voltage 0.4kV power for daily production and electricity consumption. After decades of technical iteration, this product has stable performance, mature production technology and lower overall cost, occupying a dominant position in outdoor power distribution projects worldwide.
2. Core Advantages of Oil Immersed Transformers
2.1 Excellent Heat Dissipation & Stable Long-Term Operation
Mineral oil has far better heat conduction performance than air cooling of dry type transformers. When the transformer runs under full load, the hot oil circulates naturally inside the tank, and the heat is quickly dissipated through the external corrugated radiators. Even under continuous 24-hour full-load operation in high-temperature summer environments, the winding temperature can be effectively controlled, with low risk of overheating damage.
This feature makes oil immersed transformers the preferred choice for large power consumption scenarios that require long-term uninterrupted power supply, such as industrial manufacturing bases, mining areas and centralized photovoltaic power stations.
2.2 Lower Unit Cost & Higher Cost Performance
Under the same capacity standard, oil immersed transformers save a lot of epoxy resin casting materials and fully sealed protective shells compared with dry type transformers. The simple production process greatly reduces raw material and processing costs. For customers with limited project budgets and outdoor installation conditions, oil immersed transformers can cut procurement costs by 20% to 35% on average.
For large-capacity transformers above 2500kVA, the cost gap is more obvious. Most grid engineering contractors and power station investors will prioritize oil immersed distribution transformers to control the overall project investment.
2.3 Strong Overload Capacity & Wide Power Range
Our factory produces oil immersed transformers covering a complete capacity range from 10kVA to 30000kVA, supporting short-term overload operation within a safe range. When industrial equipment is started in batches or photovoltaic power generation peaks, the transformer can bear instantaneous power surge without shutdown protection.
In contrast, dry type transformers have stricter overload limits and are more sensitive to sudden load changes, which is not suitable for projects with unstable power load fluctuations.
2.4 Simple Maintenance in Dry Outdoor Environments
For outdoor open-air substations, industrial zones and remote rural power grids with low population density, oil immersed transformers have lower daily maintenance thresholds. As long as regular oil quality testing and dust cleaning of radiators are carried out every 1–2 years, the service life can reach more than 30 years. There is no need to build special fire-proof distribution rooms, and it can be directly installed on outdoor concrete platforms to save civil construction investment.
3. Main Application Scenarios of Oil Immersed Transformers
3.1 Outdoor Power Grid & Rural Distribution Network
National and regional public power grids widely adopt oil immersed transformers for village-level power distribution. Most rural areas have wide outdoor installation space, low fire control requirements and scattered power loads. Low-cost oil immersed transformers can meet the daily electricity demand of residents and small agricultural processing factories.
3.2 Large Industrial Parks & Manufacturing Factories
Heavy industry factories, chemical plants, textile workshops and mining enterprises have high total power demand and long continuous production hours. High-capacity oil immersed transformers can stably supply power for production equipment, water pumps and air compression systems, adapting to all-day full-load operation.
3.3 Photovoltaic & Wind Energy Power Stations
New energy power stations such as ground photovoltaic bases and wind farms are almost equipped with oil immersed box transformers. The outdoor open layout of power stations matches the installation characteristics of oil immersed transformers, and the strong heat dissipation capacity can cope with power generation peaks under strong sunlight.
3.4 Remote Infrastructure Projects
Highway service stations, remote signal base stations, mountain water conservancy projects and suburban logistics parks all choose oil immersed transformers. These projects are far from densely populated areas, with loose fire safety restrictions and higher requirements for cost control and continuous power supply.
4. Difference Between Oil Immersed Transformer and Dry Type Transformer
Many overseas buyers confuse the two types of transformers during procurement. Here is a clear comparison to help you select the right product according to project conditions:
- Fire safety: Dry type transformers use flame-retardant epoxy resin, suitable for indoor underground parking lots, shopping malls and charging stations; oil immersed transformers contain flammable oil, only for open outdoor areas.
- Installation space: Dry transformers need independent fire-proof distribution rooms; oil transformers can be placed outdoors directly without special rooms.
- Budget difference: Oil immersed transformers have obvious price advantages for medium and large capacity; dry type products cost more for fire protection and sealing technology.
- Operation noise: Dry type transformers have lower running noise, suitable for residential and medical buildings; oil immersed transformers have slight oil circulation noise, suitable for non-residential outdoor areas.
- Maintenance cycle: Dry transformers basically have zero daily maintenance; oil immersed transformers need regular oil inspection and replacement every few years.
5. Standard Technical Parameters of Our Oil Immersed Transformers
As a power equipment manufacturer with 15 years of production experience, all our oil immersed transformers strictly comply with IEC 60076 international standards and CE certification requirements, supporting global grid voltage customization:
- Rated capacity: 10kVA ~ 30000kVA
- Input voltage: 10kV, 20kV, 33kV customizable
- Output voltage: 0.4kV standard, supporting special voltage matching
- Cooling mode: ONAN (natural oil circulation air cooling), ONAF (forced air cooling)
- Loss grade: Low loss, ultra-low loss energy-saving type to reduce long-term power consumption cost
- Protection accessories: Standard conservator, pressure relief valve, temperature sensor, oil level gauge
We support customized size, shell color, brand logo and internal wiring scheme to meet the tender requirements of different countries and engineering projects. All finished transformers pass full load temperature rise, insulation resistance and short-circuit resistance tests before delivery, and can provide complete test reports for third-party inspection.
6. Why Choose Our Factory’s Oil Immersed Transformers?
- Strict raw material control: We adopt high-purity oxygen-free copper windings and high-permeability cold-rolled silicon steel sheets, effectively reducing no-load loss and improving energy efficiency.
- Independent R&D energy-saving technology: Our ultra-low loss transformer series can cut power loss by more than 15% compared with ordinary models, helping customers save long-term electricity operating costs.
- Complete supporting matching service: We can supply supporting medium voltage switchgear, low voltage cabinets and box type substation shells together with oil immersed transformers to realize one-stop power distribution solution supply.
- Global after-sales support: We provide remote technical guidance for installation, operation and maintenance, and supply spare parts such as sealing rings and temperature sensors for long-term use.
- Flexible OEM & ODM service: For overseas distributors and engineering companies, we accept private label customization, parameter adjustment and packaging optimization to help you develop local market business.
