An oil immersed transformer is a type of transformer where the core and windings are fully submerged in insulating oil. The oil serves two critical purposes: providing high dielectric strength for electrical insulation, and efficiently dissipating heat generated during operation.
Compared to dry-type transformers, oil immersed units offer superior cooling, higher overload capacity, longer service life, and more compact footprint for the same power rating. They are widely used in medium- and high-voltage applications, from distribution networks to large industrial substations.
Xinhong Electrical is a professional manufacturer of high-quality oil immersed transformers, offering rated capacities from 30kVA to 30000kVA and voltage options from 6kV to 35kV.
The working principle is based on electromagnetic induction. When AC current flows through the primary winding, it creates a magnetic flux in the iron core. This flux induces a voltage in the secondary winding. The transformation ratio is determined by the turns ratio between primary and secondary windings.
In an oil filled transformer, the insulating oil continuously circulates, carrying heat away from the core and windings to the tank walls or radiators, keeping the transformer within safe operating temperatures.
High thermal efficiency – Oil provides excellent heat dissipation, allowing higher continuous ratings
Excellent insulation properties – Mineral or ester oil increases dielectric strength between live parts
Strong overload capability – Can handle peak loads better than dry-type transformers
Long operational life – With proper maintenance, decades of reliable service
Compact design – Smaller footprint than equivalent dry-type units
Oil immersed distribution and power transformers are used in:
Utility substations and grid stations
Industrial plants and heavy machinery
Renewable energy integration (solar, wind)
Outdoor pad-mounted installations
Commercial and residential power distribution
When choosing a suitable oil type transformer for your project, consider:
Load power – Select rated capacity (kVA) based on actual load, especially for motor or peak loads
Voltage requirements – Input and output voltage levels (e.g., 11kV/0.4kV)
Installation environment – Ventilation, moisture, dust, and corrosive gases
Maintenance and lifespan – Choose a reliable manufacturer with proven quality
Safety features – Overload and short-circuit protection, pressure relief devices
Xinhong Electrical offers customizable oil immersed transformers with multiple connection symbols (Dyn11, Yyn0), wavy oil tank design (no separate conservator needed), and advanced safety devices such as pressure relief valves and temperature monitoring.
Energy-efficient design – High-quality silicon steel sheets reduce losses
Flexible customization – High-voltage options: 6kV, 6.3kV, 10kV, 10.5kV, 11kV, 20kV, 22kV,30kV,33kV,35kV; low-voltage: 400V, 415V, etc.
Certified quality – ISO9001, CCC, CE, IEC verified
Global service – Comprehensive after-sales and technical support
The oil immersed transformer remains the most reliable solution for medium- to high-voltage power systems. Whether for grid modernization, industrial expansion, or renewable energy projects, choosing a high-performance transformer from a trusted manufacturer is essential.
Xinhong Electrical provides durable, efficient, and cost-effective oil immersed transformers tailored to your specific needs. Contact us today for a custom solution.
