The Three-Phase Oil-Immersed Sealed Distribution Transformer represents a high-performance line of fully sealed, three-phase, oil-immersed distribution transformers designed for 35kV grid applications where reliability and low maintenance are paramount. Engineered with an Off-Circuit Tap Changer (OCTC) for stable voltage adjustment and manufactured in strict compliance with Chinese National Standards GB1094 and GB/T6451, this transformer is built for long-term, trouble-free operation. Its sealed tank design and robust construction make it an ideal choice for utilities and industrial power distribution systems.
Product Features
• Fully Sealed, Maintenance-Reduced Design
The innovative "M" (fully sealed) construction in the model code indicates a maintenance-free design that effectively isolates the internal oil and insulation from the external environment, significantly extending service life and reliability.
• Stable Voltage Regulation
Equipped with a reliable Off-Circuit Tap Changer (OCTC) offering an adjustment range of ±2x2.5%, allowing for manual or electric fine-tuning of the output voltage when de-energized to maintain optimal power quality.
• Exceptional Mechanical Robustness
The core and winding assembly is secured with a unique three-point (top, middle, bottom) positioning system with special anti-loosening and anti-vibration measures. This ensures structural integrity during transport and operation, often eliminating the need for core inspection upon installation.
• Leak-Proof & Durable Construction
The tank is fabricated from high-quality steel plates for superior mechanical strength. All gaskets and seals utilize advanced, long-lasting acrylate rubber compounds that resist aging, guaranteeing an effective, long-term seal against oil leakage.
• Tiered High-Efficiency Performance
Offered in multiple energy efficiency levels (Grade 1, 2, 3 as per standards), allowing customers to select the optimal balance between initial investment and long-term operational cost savings based on specific load profiles.
Specifications & Parameters
| Category | Specification / Description |
| Model Code | S [Design No.] M - [Rated Capacity (kVA)] / [Rated Voltage (kV)] Example: S13-M-10000/35 |
| Type | Three-Phase, Oil-Immersed, Double-Winding, Fully Sealed (M) Tank |
| Rated Voltage | 35 kV (Primary Side) Voltage Regulation Off-Circuit Tap Changer (OCTC): ±2×2.5% |
| Rated Capacity Range | From 3,150 kVA to 31,500 kVA (Standard range as per table) |
| Standards Compliance | GB1094 (Power Transformers), GB/T6451 (Technical Parameters &Requirements) |
| Cooling Method | ONAN (Oil Natural Air Natural) |
Key Performance Data (Efficiency Tiers for 35kV Series)
The table below outlines the guaranteed no-load and load loss values for different efficiency grades. Short-circuit impedance is designed as per requirements (e.g., 7%, 8%, 10% for various capacities).
| Rated Capacity (kVA) | Efficiency Grade 1 |
Efficiency Grade 2 |
Efficiency Grade 3 |
|||
| No-Load Loss (kW) | Load Loss @75°C (kW) | No-Load Loss (kW) | Load Loss @75°C (kW) | No-Load Loss (kW) | Load Loss @75°C (kW) | |
| 3150 | 1.7 | 20.7 | 2.0 | 20.7 | 2.4 | 21.9 |
| 5000 | 2.4 |
28.2 | 2.8 | 28.2 | 3.5 | 29.7 |
| 10000 | 4.8 | 40.8 | 5.7 | 40.8 | 7.0 | 43.0 |
| 20000 | 7.9 | 71.6 | 9.4 | 71.6 | 11.5 | 75.5 |
| 31500 | 11.1 | 100.8 | 13.1 | 100.8 | 16.2 | 106.4 |
Packaging, Warranty & Certifications Packaging：
The transformer is shipped as a fully assembled unit. The main tank is sealed and filled with dry, inert gas (nitrogen) for protection during transit. It is securely mounted on a heavy-duty steel skid base designed for roll-on/roll-off and heavy-lift transport. Detachable coolers and accessories are individually packed in robust wooden crates.
Warranty：
We provide a standard 12-month warranty from the date of successful commissioning or 18 months from the date of shipment, whichever occurs first. This warranty covers defects in materials and workmanship under normal operation and service.
Certifications & Testing：
Our manufacturing quality management system is certified to ISO 9001. The product is designed, tested, and produced in strict accordance with GB1094 and GB/T6451 standards. Each unit undergoes comprehensive routine tests, including turns ratio, winding resistance, impedance voltage, no-load & load loss measurement, and dielectric withstand tests. Complete test reports are provided.
