250KVA 6.6KV Oil Immersed Transformer

The 250KVA 6.6KV Oil Immersed Transformer is a low-loss distribution transformer developed by GUANGBIAN based on the S11 series, designed to improve energy efficiency and reduce no-load losses for industrial and utility power systems. It is optimized for different regional grid conditions, including voltage fluctuation, climate, and load variation, ensuring stable operation in diverse environments.

The transformer steps down 6.6KV to 400V/415V, suitable for industrial and commercial power distribution. It supports copper and aluminum windings for different efficiency and cost requirements, and uses an ONAN oil-immersed cooling system to ensure reliable heat dissipation and continuous operation under load.

It is widely applied in:

● Medium voltage distribution networks (6.6KV systems)

● Industrial manufacturing facilities

● EPC and infrastructure power projects

● Commercial substations and utility grids

Compared with dry-type transformers, oil-immersed units provide:

● Higher overload tolerance

● Better thermal stability

● Longer operational lifespan

● Stronger resistance to short-circuit conditions

Key Features & Advantages

High Efficiency & Low Loss Design

The transformer is engineered with optimized core material to reduce no-load losses and improve energy efficiency. This helps reduce long-term operational electricity costs for industrial users.

Strong Short-Circuit Resistance

The winding structure is mechanically reinforced to withstand frequent grid fluctuations and short-circuit conditions, ensuring stable operation in unstable power environments.

Flexible Winding Options

● Copper winding: higher efficiency, better conductivity, longer lifespan

● Aluminum winding: cost-effective solution for budget-sensitive projects

Excellent Heat Dissipation

The ONAN cooling system allows natural oil circulation, ensuring stable temperature control without additional auxiliary cooling systems.

Long Service Life

Designed for a 20–30 year operational lifespan, making it suitable for long-term infrastructure investment projects.

Technical Document 

Operating Environment

Temperature Conditions:

Long-term Operating Ambient Temperature: -25℃ ~ +45℃.

Maximum Operating Ambient Temperature: Not exceeding +50℃.

Storage and Transportation Temperature:

-40℃ ~ +60℃.

Humidity Conditions:

Relative Humidity: ≤95% at 25℃

Altitude Requirements:

Rated Altitude Adaptation Range: ≤1000 meters

Why 6.6KV System Matters?

The 6.6KV medium voltage system is commonly used in industrial and regional distribution networks where moderate capacity and stable voltage control are required.

Compared with higher voltage systems such as 11KV:

● Lower insulation stress on equipment

● More suitable for medium-scale industrial loads

● Better cost efficiency in compact distribution networks

This makes the 6.6KV transformer an ideal solution for localized power distribution systems.

Our Factory

Sheet metal workshop

Foil winding workshop

Winding workshop

Winding oven workshop

Transformer assembly workshop

Transformer commissioning workshop

FAQ

1.What is a 250KVA 6.6KV Oil Immersed Transformer used for?

It is used for medium-scale power distribution in industrial plants, commercial buildings, and utility systems.

2.What is the difference between 6.6KV and 11KV transformers?

6.6KV transformers are typically used for smaller or medium industrial loads, while 11KV systems are used for larger distribution networks.

3.Can the transformer be customized?

Yes, we provide OEM customization including winding material, vector group, and structural design.

4.Is copper winding better than aluminum?

Copper winding offers higher efficiency and better durability, while aluminum is more cost-effective.