China Oil-Immersed Cooling Transformer - Reliable Power Supply Solution from Trusted Suppliers & Factory for Industrial Use
Product Specification
Basic Information
| Item | Specification |
| Product Model | Example: S11-M-500/10, S13-R-1000/20, S15-H-2500/35 (S=Three-Phase; 11/13/15=Efficiency Class; M/R/H=Structural Type; Capacity kVA/HV kV) |
| Rated Capacity（Sn） | 30kVA~5000kVA (ONAN: 100% rated capacity; ODAF: 130%; ODWF: 160%) |
| Phase/Frequency | Three-Phase (standard); 50Hz/60Hz (±1% tolerance, customizable for 400Hz special use) |
| Connection Group | Dyn11 (default for distribution), Yd11 (for power transformer); Yyn0 (optional) |
| Cooling Type | ONAN (Oil Natural Air Natural) / ODAF (Oil Directed Air Forced) / ODWF (Oil Directed Water Forced) |
Operating & Environmental Conditions
| Parameter | Details |
| Ambient Temperature | -25℃~40℃ (standard); -40℃~45℃ (low-temperature/high-temperature models with modified oil). |
| Altitude | ≤1000m (derate 5% at 1500m, 10% at 3000m, 15% at 4000m). |
| Humidity | ≤90% @25℃ (no condensation); ≤50% @40℃. |
| Seismic Resistance | GB 50260-2013 / IEC 60076-11, 7-degree intensity (0.15g acceleration); 8-degree optional. |
| Protection Class | IP23 (outdoor, dust/rainproof) / IP20 (indoor). |
Losses & Impedance (Typical Values by Efficiency Class)
| Efficiency Class | Parameter | 500kVA/10kV Example | Test Condition |
| S11 (IEC IE1) | No-Load Loss (Po) | ≤810W | Rated voltage/frequency |
| Load Loss (Pk) | ≤5200W | Rated current, 75℃ | |
| S13 (IEC IE2) | No-Load Loss (Po) | ≤650W (20% lower than S11) | Rated voltage/frequency |
| Load Loss (Pk) | ≤4800W | Rated current, 75℃ | |
| S15 (IEC IE3) | No-Load Loss (Po) | ≤520W (36% lower than S11) | Rated voltage/frequency |
| Load Loss (Pk) | ≤4500W | Rated current, 75℃ | |
| All Classes | Short-Circuit Impedance (Uk%) | 4%~6% (10kV); 6%~8% (35kV) | 75℃, ±10% tolerance |
| No-Load Current (Io%) | ≤1.0% (30~250kVA); ≤0.6% (≥315kVA) | Rated voltage |
ⓘ Efficiency Compliance: GB 20052-2024 Class 2 (S11/S13) / Class 1 (S15); IEC 60076-11 IE1/IE2/IE3
Example S13-500/10 Key Specs
| Item | Value |
| Rated Capacity | 500kVA |
| HV/LV Voltage/Current | 10kV/28.87A; 0.4kV/721.7A |
| No-Load/Load Loss | ≤650W / ≤4800W |
| Short-Circuit Impedance | 4.5% |
| Cooling Method | ONAN |
| Core Material | 30Q130 Silicon Steel |
| Protection Class | IP23 |
ⓘ Customizable for special voltages (e.g., 6.3kV, 13.8kV), high-altitude (≥3000m), or explosion-proof (Ex d IIB T4) requirements. All parameters verified by SGS/Intertek.
Advantages
Leveraging the high thermal conductivity of insulating oil, the transformer efficiently transfers heat generated by internal coils and cores to the tank and external radiators, enabling stable operation even under high load or long continuous working conditions, preventing overheating-induced damage.
Insulating oil enhances electrical insulation between internal parts, effectively isolating air, moisture, and dust. This reduces the risk of leakage or short circuits, making the transformer highly reliable in humid, dusty, or harsh industrial environments.
The oil-immersed structure allows the transformer to withstand short-term overloads such as sudden power surges in industrial production or peak civilian electricity use. Its ability to absorb and dissipate excess heat quickly minimizes performance degradation and avoids unexpected shutdowns.
The sealed oil tank protects internal components from external corrosion, dust, and mechanical wear. High-quality insulating oil maintains stable performance over time, slowing the aging of coils and insulation materials. The design life typically exceeds 20 years.
The sealed structure reduces exposure to external contaminants, lowering the need for frequent internal cleaning or part replacement. Routine maintenance only involves periodic checks of oil level, oil quality, and tank tightness—simplifying operations and cutting long-term costs.
Due to its excellent insulation and heat dissipation, the Oil-Immersed Transformer is widely used in high-voltage power grids, large industrial plants, and infrastructure projects. It meets strict voltage resistance standards, ensuring safe and efficient high-power transmission.
Product Display
Application
I. Power System: Core Equipment for High-Voltage Transmission & Distribution
As a cornerstone of power grids, the Oil-Immersed Transformer is indispensable for voltage conversion and power transmission, especially in:
High-voltage power transmission networks: Used in long-distance power transmission between regional power grids (e.g., from power plants to central substations). Its excellent insulation and heat dissipation enable stable operation under high voltage (110kV, 220kV, or even 500kV) and large current, minimizing energy loss during long-distance transmission.
Substation voltage transformation: Installed in primary and secondary substations, it steps down high-voltage power from transmission lines to medium/low voltage (10kV, 0.4kV) for subsequent distribution to industrial users and residential areas, matching the voltage requirements of different end-users.
Urban & rural distribution networks: For areas with high power demand or large coverage (e.g., suburban industrial zones, rural townships), it adapts to fluctuating loads and harsh outdoor conditions, ensuring reliable power supply to scattered users.
II. Industrial Sector: Reliable Power Supply for Heavy-Duty Operations
Its ability to withstand high loads and harsh environments makes it a top choice for industrial scenarios with continuous, high-intensity power needs:
Heavy industry & manufacturing: Applied in steel mills, chemical plants, and machinery factories, it powers high-power equipment (e.g., blast furnaces, chemical reactors, production lines). Its strong overload capacity copes with sudden power surges during peak production, while its sealed structure resists dust, corrosive gases, and mechanical vibrations.
New energy power generation supporting: Used in solar photovoltaic (PV) and wind power plants as "step-up transformers". It boosts the low-voltage electricity generated by PV panels or wind turbines to high voltage, enabling efficient integration into the national power grid—critical for large-scale new energy utilization.
III. Civil Infrastructure & Large-Scale Buildings
For civil scenarios requiring stable, long-term power supply and low maintenance, it is widely adopted in:
Large commercial & public buildings: Installed in shopping malls, hotels, hospitals, and airports, it provides continuous power for air conditioning, elevators, lighting, and medical equipment. Its long service life (over 20 years) and low maintenance needs reduce operational costs for building managers.
Data centers: Data centers operate 24/7 with high power density. The Oil-Immersed Transformer's efficient heat dissipation reduces the load on the cooling system, while its stable power supply prevents downtime of servers and data storage devices.
Transportation hubs: Used in high-speed rail stations, subway systems, and ports, it supports the power needs of signal systems, traction power (for trains), and logistics equipment. Its resistance to temperature fluctuations and humidity ensures reliable operation in outdoor or semi-outdoor installations.
IV. Special Harsh Environments
Its robust sealed structure and corrosion resistance make it suitable for challenging conditions:
Mining & oilfields: In underground mines or remote oilfields, where environments are humid, dusty, or exposed to corrosive substances, the transformer's insulation oil and sealed tank protect internal components from damage, ensuring power supply for mining machinery or oil extraction equipment.
Remote off-grid systems: For isolated areas (e.g., mountainous villages, island communities) with independent power systems powered by small hydropower or diesel generators, the transformer's low maintenance requirements and long lifespan reduce the need for frequent on-site repairs, ensuring stable daily power.
Frequently Asked Questions
What is the difference between S11, S13, and S15 efficiency classes?
S11, S13, and S15 represent increasing levels of energy efficiency. S11 (IEC IE1) is the standard class; S13 (IEC IE2) offers approximately 20% lower no-load losses than S11; and S15 (IEC IE3) achieves up to 36% lower no-load losses than S11. Higher efficiency classes reduce long-term energy consumption and operating costs, and comply with stricter standards such as GB 20052-2024 and IEC 60076-11.
What cooling types are available and how do they affect capacity?
Three cooling methods are available: ONAN (Oil Natural Air Natural) supports 100% of rated capacity; ODAF (Oil Directed Air Forced) increases usable capacity to 130%; and ODWF (Oil Directed Water Forced) supports up to 160% of rated capacity. The choice depends on the application environment, available cooling infrastructure, and load requirements.
Can the transformer be used at high altitudes or in extreme temperatures?
Yes. For altitudes above 1000m, derating is applied: 5% at 1500m, 10% at 3000m, and 15% at 4000m. For extreme temperatures, special low-temperature models (down to -40℃) and high-temperature models (up to 45℃) are available using modified insulating oil. Custom configurations for high-altitude environments (≥3000m) can also be specified.
What voltage customization options are supported?
Beyond standard voltages (e.g., 10kV, 35kV), the transformer supports customization for special primary voltages such as 6.3kV, 13.8kV, and other non-standard values. Connection groups including Dyn11, Yd11, and Yyn0 are available. Frequency options include 50Hz, 60Hz, and 400Hz for special applications. All custom configurations are verified by SGS or Intertek.
What industries and applications are these transformers best suited for?
Oil-Immersed Transformers are suitable for a wide range of applications including high-voltage power transmission networks, industrial facilities (steel mills, chemical plants, manufacturing), new energy power generation (solar PV and wind farms), large commercial and public buildings, data centers, transportation hubs, and special environments such as mining sites, oilfields, and remote off-grid communities.
What maintenance is required and how long is the service life?
Routine maintenance is minimal and involves periodic inspection of oil level, oil quality, and tank tightness. The sealed structure significantly reduces internal contamination and the need for frequent part replacement. The design service life of these transformers typically exceeds 20 years, making them a cost-effective long-term investment for power infrastructure.