Oil immersed transformer, with a core made of stacked silicon steel sheets, undergoes annealing treatment to restore its magnetic conductivity to its pre processing level. This product has low no-load loss, low no-load current, low noise, superior mechanical and electrical performance, and is stable and reliable. It is the preferred product for transformer replacement.
The iron adopts a stepped core joint, which reduces no-load loss and no-load current. The high and low voltage windings adopt a continuous axial oil passage, and U-shaped pads are used between the wire cakes to balance the winding axis and increase the mechanical strength of the winding.



Core indicators | Unit | Parameter |
HV Rated Voltage | kV | 11/11.5 |
LV Rated Voltage | kV | 0.415 |
Rated Frequency | Hz | 50 |
Rated Capacity | kVA | 200–2500 |
Tap Range | % | ±5 OR ±2×2.5 |
Connection Group | — | Dyn11 |
Short‑circuit Impedance | % | 4.0–5.0 |
1min PF Withstand Voltage | kV | 38 |
Lightning Impulse Withstand | kV | 75 |
Standards | — | MS IEC 60076 |

Oil immersed transformer is a power transformer that uses transformer oil as insulation and cooling medium.
It is the most widely used type of transformer in the power system, with excellent insulation performance, good heat dissipation effect, strong overload capacity, stable operation and other characteristics.
1、 Core performance: excellent insulation, efficient heat dissipation, strong overload capacity;
2、 Structural design: Mature technology, reliable sealing, suitable for outdoor use;
3、 Installation and operation: easy to operate, low maintenance cost, suitable for engineering applications;
4、 Cost and Scenario: High cost-effectiveness, full capacity coverage, adaptable to multiple scenarios;
Excellent cost performance ratio: Under the same capacity, the manufacturing cost of oil immersed transformers is 30% to 50% lower than that of dry-type transformers, and there is no need for additional power consumption for heat dissipation. The energy consumption cost for long-term operation is also lower, making it the economical choice for box type substations.
Wide capacity coverage: The rated capacity can range from 30kVA (small capacity American box transformer) to 3150kVA and above (large capacity European box transformer), meeting the full scenario needs of Malaysia from light load distribution in residential areas to heavy load distribution in industrial parks.
Core adaptation scenarios:
Outdoor power distribution: European/American box type substations, outdoor pole mounted transformers, floor standing distribution transformers;
Medium to large capacity power distribution: industrial parks, oilfield terminals, commercial plazas, urban public power distribution;
Distribution in harsh environments: salt spray areas along the coast of Malaysia, high temperature and humidity areas, and industrial areas with less dust.
Strong localization adaptability: For the tropical climate of Malaysia, 45 # high ignition point transformer oil can be selected (with better temperature resistance and prevention of high-temperature oil leakage), combined with anti condensation and anti UV design, which can operate stably in an environment of -10 ℃~+50 ℃ for a long time.
Advantages and Limitations: Oil-immersed Transformer vs Dry-type Transformer
| Comparison Dimension | Oil-immersed Transformer | Dry-type Transformer |
| Insulation & Heat Dissipation | Excellent insulation performance, high heat dissipation efficiency, and strong overload capacity | Insulation depends on air, poor heat dissipation, and weak overload capacity |
| Cost | 30%~50% lower manufacturing cost, low operation and maintenance cost | High manufacturing cost; regular insulation inspection required, resulting in high operation and maintenance cost |
| Service Life | 20~30 years (hermetically sealed type) | 10~15 years (conventional type) |
| Outdoor Adaptability | Strong protection performance, suitable for outdoor high temperature, salt spray and rainy conditions | Weak protection performance; additional protective box required for outdoor application |
| Capacity Coverage | Full capacity coverage from 30kVA to 3150kVA and above | Mostly 30~1250kVA, extremely high manufacturing cost for large capacity |
| Fire Safety | Flammable oil medium, potential fire risk in case of internal short circuit; special fire prevention measures required | Incombustible insulation material, good fire safety performance, no fire spreading risk |
| Installation & Mobility | Relatively heavy due to oil tank and dielectric oil; forklift/crane required for transportation and installation, low mobility | Light weight, convenient for transportation and installation, high mobility |
| Environmental Impact | Risk of oil leakage for non-hermetically sealed type, which may cause environmental pollution (avoidable by hermetically sealed type) | No medium leakage, green and environmentally friendly, no pollution risk |
| Applicable Scenarios | Outdoor power distribution, medium and large capacity power distribution, industrial and municipal power distribution | High-rise buildings, basements, densely populated areas, clean indoor power distribution |