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The SZ13 series 6–10 kV oil-immersed transformers are key power transmission and distribution components within medium-voltage power systems, serving an important function in voltage conversion and power distribution. Their primary role is to step down higher-voltage electricity—typically originating from 35 kV or above transmission networks—to the 6–10 kV medium-voltage range for safe distribution to industrial facilities, commercial complexes, and residential areas. Conversely, they can also step up low-voltage power generated by small-scale sources (such as industrial self-supply generators) to the 6–10 kV level for grid interconnection.
This voltage regulation process ensures that electrical energy is delivered to end-users safely, efficiently, and reliably while reducing transmission losses and contributing to the stability of the overall power supply system.
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Product model |
Loss level |
Special purpose or special structure |
Rated capacity kV.A |
System nominal voltage kV |
Special usage environment |
Energy efficiency level |
| D-Single-phase S-Three-phase F-Air cooling Z-On load voltage regulation |
11 13 14 20 22 |
M-Fully sealed M.RL-Fully sealed three-dimensional coil iron core |
GY-Plateau TA-Tropic TH-Humid tropical zone |
NX3 NX2 NX1 |
Our company manufactures three-phase oil-immersed distribution transformers featuring an advanced body insulation design that significantly enhances short-circuit withstand capability. The core is constructed from premium cold-rolled silicon steel laminations. For the high-voltage winding, we utilize high-grade oxygen-free copper wire arranged in a multi-layer cylindrical configuration. All fasteners receive specialized anti-corrosion treatment. The unit incorporates a corrugated, fully-sealed tank. This product is characterized by high efficiency and low losses, leading to substantial savings in power consumption and operational expenses. It delivers notable social benefits and is recognized as a nationally-promoted high-tech product.
Reliable structure
Building upon conventional designs and proven technology, our company has implemented numerous enhancements, including:
① The use of spiral coils with longitudinal oil ducts for superior internal cooling.
② Enhanced effective support at the coil ends, providing increased resilience against short-circuit currents.
③ The adoption of innovative lifting and core positioning systems to ensure greater reliability during long-distance transport and operation.
④ A variety of other unique and robust structural features designed to serve our customers.
⑤ Models with higher performance ratings, which embody a more advanced level of technical sophistication.
⑥ A fully-sealed tank structure that isolates the transformer from the atmosphere. This prevents and retards oil degradation and insulation moisture absorption, boosts operational reliability, and eliminates the need for maintenance under normal operating conditions.
High quality materials
All raw materials undergo stringent quality inspections, and their manufacturers are rigorously assessed in compliance with the ISO9000 national standard.
① We select oxygen-free copper wire with lower resistivity, which then undergoes additional surface treatments to achieve a smoother finish free of burrs and sharp edges. This results in reduced load loss and more dependable transformer electrical performance.
② High-quality silicon steel sheets are selected. For higher performance levels, we use sheets with lower unit loss to minimize transformer no-load loss.
③ High-grade laminated wood insulation components are employed, ensuring they remain crack-free and immovable even under short-circuit current stress.
④ Deep-filtered transformer oil is selected, featuring lower levels of water, gas, and impurities for more reliable transformer operation.
⑤ Premium rubber sealing materials are used to effectively resist aging and prevent any leakage.
Normal usage conditions
Altitude: Not exceeding 1000m;
Ambient Temperature: Maximum temperature: +40°C; Average temperature of the hottest month: +30°C; Maximum yearly average temperature: +20°C; Minimum outdoor temperature: -25°C.
Power Supply Voltage: The waveform should approximate a sine wave. For three-phase transformers, the three-phase supply voltage should be substantially symmetrical.
Installation environment: No obvious pollution in the installation environment; Ground acceleration caused by earthquake ag: Horizontal direction below 3m/s², vertical direction below 1.5m/s²
Special usage conditions
Any special service conditions falling outside the normal parameters specified above must be clearly stated during the inquiry and order placement process.
| Rated capacity
kV.A |
Voltage combination and tap range | Connection
group |
No-load loss kW | Load loss kW | No-load
current % |
Short-circuit
impedance % |
||
| High
voltage kV |
High voltage tap
range % |
Low
voltage kV |
||||||
| 200 | 6 6.3 10 10.5 |
±4×2.5 | 0.4 | Dyn11 Yyn0 |
0.30 | 2.90 | 0.8 | 4.0 |
| 250 | 0.35 | 3.42 | 0.72 | |||||
| 315 | 0.42 | 4.10 | 0.72 | |||||
| 400 | 0.51 | 4.95 | 0.64 | |||||
| 500 | 0.60 | 5.89 | 0.64 | |||||
| 630 | 0.77 | 7.26 | 0.48 | 4.5 | ||||
| 800 | 0.90 | 8.89 | 0.48 | |||||
| 1000 | 1.00 | 10.4 | 0.48 | |||||
| 1250 | 1.25 | 12.3 | 0.4 | |||||
| 1600 | 1.54 | 14.7 | 0.4 | |||||
| 2000 | 1.82 | 18.6 | 0.32 | 5.0 | ||||
| 2500 | 2.10 | 21.6 | 0.32 | |||||
Note: When the average load rate of the transformer is between 35% and 40%, the highest operating efficiency can be obtained by using the loss values in the table.