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Overview
The SZ□-35KV Oil-Immersed Transformer is a highly efficient, on-load voltage regulating transformer designed for power systems operating at 35kV and below. Operating under a frequency of 50Hz, this transformer is a key component in medium and small-sized substations. It provides reliable power distribution for industrial, agricultural, and lighting applications.

Manufactured with precision and built using advanced domestic and international technology, the SZ□-35KV transformer incorporates optimized design techniques and modern materials. This results in a more compact structure, enhanced electric and mechanical strength, and superior heat dissipation performance.
Standards Compliance
This transformer complies with national and international quality standards ensuring safety, durability, and efficient operation.
Operating Conditions
- Altitude: ≤1000m
- Ambient Temperature:
- Maximum: +40℃
- Monthly Average: +30℃
- Yearly Average: +20℃
- Installation Conditions:
- Maximum inclination: <3°
- Free from significant dust, corrosive gases, and flammable vapors
Structural Features
1. Iron Core
The iron core is fabricated using high-grade cold-rolled silicon steel sheets. The core design incorporates:
- Fully biased multi-stage joints
- Non-punch hole wind cores
- Stainless steel stays and epoxy glass tape reinforcement
This structure minimizes energy losses and reduces operational noise, ensuring long-term performance.

2. Coil Design
The winding conductors are manufactured from high-purity oxygen-free copper wires, available as enameled wire or paper-wrapped flat copper wire. The coil structures include:
- Drum type
- Spiral type
- Improved spiral
- Continuous winding
- Staggered layout
This design ensures uniform distribution of magnetic flux and prevents hot-spot formation.
3. Oil Tank
The oil tank is available in:
- Barrel-type or shielded construction
- Corrugated plates or electroplated radiators for cooling
Instead of wheels, the base is welded to meet national gauge standards for stable, fixed installation.
4. Safety & Protection Devices
Based on customer and standard requirements, the transformer can be equipped with:
- Pressure relief valve
- Gas relay
- Signal thermometer
- Oil conservator
- Oil sample valve
- Oil filter system
These features ensure system integrity during overvoltage or fault conditions.
Technical Specifications
SZ9-35KV Transformer Technical Data
Rated Capacity (kVA) | H.V (kV) | Tapping Range | L.V (kV) | Connection | No-load Loss (W) | Load Loss (W) | No-load Current (%) | Impedance (%) |
---|---|---|---|---|---|---|---|---|
2000 | 35 | ±3×2.5 | 6.3/10.5 | Yd11 | 2900 | 20200 | 0.9 | 6.5 |
2500 | 3400 | 22700 | 0.9 | |||||
3150 | 35-38.5 | 4100 | 26000 | 0.8 | 7 | |||
4000 | 4900 | 30700 | 0.8 | |||||
5000 | 5800 | 36000 | 0.75 | |||||
6300 | 7000 | 38700 | 0.75 | 8 | ||||
8000 | Ynd11 | 9900 | 43000 | 0.7 | ||||
10000 | 11600 | 50600 | 0.7 | |||||
12500 | 13800 | 59900 | 0.7 | |||||
16000 | 16200 | 73000 | 0.7 | |||||
20000 | 19500 | 84600 | 0.7 | |||||
25000 | 22500 | 100200 | 0.7 | 10 | ||||
31500 | 26400 | 124000 | 0.6 |
SZ11-35KV Transformer Technical Data
Rated Capacity (kVA) | H.V (kV) | Tapping Range | L.V (kV) | Connection | No-load Loss (W) | Load Loss (W) | No-load Current (%) | Impedance (%) |
2000 | 35 | ±3×2.5 | 6.3/10.5 | Yd11 | 2300 | 19240 | 0.8 | 6.5 |
2500 | 2720 | 20640 | 0.8 | |||||
3150 | 35-38.5 | 3230 | 24710 | 0.72 | 7 | |||
4000 | 3870 | 29160 | 0.72 | |||||
5000 | 4640 | 31200 | 0.68 | |||||
6300 | 6.3/6.6/10.5 | Ynd11 | 5630 | 36770 | 0.68 | 7.5 | ||
8000 | 7870 | 40610 | 0.6 | |||||
10000 | 9280 | 48050 | 0.6 | |||||
12500 | 10940 | 56860 | 0.56 | 8 | ||||
16000 | 13170 | 70320 | 0.54 | |||||
20000 | 15570 | 82780 | 0.54 |
SZ13-35KV Transformer Technical Data
Rated Capacity (kVA) | H.V (kV) | Tapping Range | L.V (kV) | Connection | No-load Loss (W) | Load Loss (W) | No-load Current (%) | Impedance (%) |
2000 | 35 | ±3×2.5 | 6.3/10.5 | Yd11 | 2300 | 19200 | 0.5 | 6.5 |
2500 | 2720 | 20600 | 0.5 | |||||
3150 | 35-38.5 | 3230 | 24700 | 0.5 | 7 | |||
4000 | 3870 | 29100 | 0.5 | |||||
5000 | 4640 | 34200 | 0.5 | |||||
6300 | 5630 | 36700 | 0.5 | 8 | ||||
8000 | 6.3/6.6/10.5 | Ynd11 | 7870 | 40600 | 0.4 | |||
10000 | 9280 | 48000 | 0.4 | |||||
12500 | 1090 | 56800 | 0.35 | |||||
16000 | 1310 | 70300 | 0.35 | |||||
20000 | 1550 | 82100 | 0.35 | |||||
25000 | 1830 | 97800 | 0.3 | 10 | ||||
31500 | 2180 | 716000 | 0.3 |
Frequently Asked Questions
1. What is the purpose of an oil-immersed transformer in modern power systems?
Oil-immersed transformers provide efficient insulation and superior heat dissipation, making them suitable for medium-voltage networks and industrial applications.
2. How does the SZ□-35KV transformer support voltage regulation?
The SZ□-35KV transformer features on-load voltage regulation capability, allowing it to adapt to grid voltage fluctuations in real time without service interruption.
3. What makes this transformer energy-efficient?
With advanced materials, optimized coil and core designs, and reduced no-load and load losses, this transformer significantly improves overall energy efficiency.