Our 10kV Oil-Immersed Distribution Transformers are the backbone of modern power grids, engineered to deliver exceptional reliability and energy efficiency. Available in capacities from 25kVA to 2500kVA, these transformers are designed for 10kV (and 11kV) medium-voltage networks, stepping down power for industrial, commercial, and residential use.
The S11 and S13 series represent the pinnacle of oil-filled technology. Featuring a fully encapsulated (hermetically sealed) design, these units eliminate the need for an oil conservator, significantly reducing maintenance requirements and preventing oil aging. With a core built from high-permeability grain-oriented silicon steel, our transformers offer significantly lower no-load losses compared to traditional models.
High-Efficiency Core (S11/S13): Utilizing high-quality cold-rolled grain-oriented silicon steel with a 45° full-miter joints design to minimize no-load loss and noise levels.
Hermetically Sealed Construction: The corrugated tank design acts as a heat radiator and expansion element. Being fully sealed from the atmosphere prevents oxygen and moisture from entering, extending the oil and insulation life to 30+ years.
Superior Thermal Performance: High-grade mineral insulating oil provides excellent dielectric strength and efficient heat dissipation, ensuring stable operation even under continuous peak loads.
Compact & Low Noise: The optimized winding structure and rigid tank assembly significantly reduce vibration and electromagnetic noise, making them suitable for urban residential installations.
Robust Short-Circuit Withstand: High-strength structural steel and specialized winding techniques ensure the transformer can withstand the mechanical stresses of sudden external short circuits.
| Feature | Detailed Specifications |
| Rated Capacity | 25kVA to 2500kVA |
| Primary Voltage (HV) | 10kV / 10.5kV / 11kV |
| Secondary Voltage (LV) | 0.4kV / 400V / 415V |
| Vector Group | Dyn11 / Yyn0 (Customizable) |
| Cooling Method | ONAN (Oil Natural Air Natural) |
| Tap Range | ±5% or ±2x2.5% (Off-Circuit Tap Changer) |
| Efficiency Standard | S11 / S13 (Tier 1 & Tier 2) |
| Standards Compliance | IEC 60076, CE, ISO9001 |
Urban & Rural Grids: Reliable secondary distribution for metropolitan residential blocks and agricultural electrification.
Industrial Parks: Providing stable power for factories, mining sites, and manufacturing plants with high inductive loads.
Commercial Infrastructure: High-efficiency power supply for shopping malls, hospitals, and high-rise office towers.
Renewable Energy Sites: Stepping down voltage for auxiliary power systems in large-scale solar and wind farms.
Maintenance-Free Operation: The fully encapsulated design means no oil testing or top-ups are required under normal operating conditions, drastically reducing O&M costs.
Eco-Friendly & Low Loss: The S13 series provides up to 30% reduction in no-load losses compared to the S11, significantly lowering the total cost of ownership through energy savings.
Quality Assured Components: We use high-purity oxygen-free copper for windings and premium-grade porcelain or resin bushings for HV/LV terminals.
Comprehensive Testing: Every unit undergoes a full battery of routine tests, including turns ratio, winding resistance, insulation impedance, and full-load loss verification before dispatch.
Q: What is the main difference between S11 and S13 models?
A: The S13 is the upgraded version with superior core materials and winding techniques, resulting in lower energy losses (approx. 25-30% less no-load loss) and a quieter operation compared to the S11.
Q: Can these transformers be used in tropical or high-altitude regions?
A: Yes. We can customize the cooling fins, oil grade, and bushing creepage distances to suit high-ambient temperatures or altitudes above 1000m.
Q: Do you offer Off-Circuit or On-Load Tap Changers (OLTC)?
A: Our standard distribution models feature an Off-Circuit Tap Changer (OCTC) with ±2.5% or ±5% adjustment. For projects requiring active voltage regulation, we can integrate an OLTC on larger kVA units.


The three-phase oil-immersed distribution transformer produced by our company adopts a new insulation structure to improve the short-circuit resistance. The core is made of high guality cold emulsion silicon steel sheet. The high voltage winding is made of high quality oxygen-free copper wire and adoptsmulti-layer cylinder structure.All fasteners are specially loose-proof.
The product has the high efficiency,the low loss characteristic, may save the massive electricity consumption and the operation expense,the social benefit is remarkable,isthe national promotion high and new technology product.










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Product name
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Dry-type Electric Transformer
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Place of origin
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Zhejiang,China
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