S9 Type Oil-Immersed Power Transformer of 35 kV – General

Overview

The S9 type oil-immersed power transformer of 35 kV is a widely applied high-voltage distribution transformer designed for reliable power transmission and distribution in utility and industrial networks. It features mature technology, stable performance, and proven operational reliability, making it suitable for long-term continuous operation under various environmental conditions.

As a traditional oil-immersed transformer, the S9 series uses high-quality insulating oil for both cooling and insulation, ensuring efficient heat dissipation and strong dielectric performance. It has been extensively deployed in substations, industrial facilities, and rural electrification projects.

Main Characteristics

The S9 type transformer adopts optimized electromagnetic design and advanced manufacturing processes to ensure dependable performance.

Key characteristics include:

• Reliable oil-immersed insulation system

• Strong dielectric strength for 35 kV networks

• Stable temperature rise under rated load

• Robust mechanical structure with high short-circuit resistance

• Proven long-term operational stability

These features make the S9 type transformer suitable for harsh operating environments.

Core and Winding Structure

The S9 series uses a high-quality laminated silicon steel core with low hysteresis loss and low magnetization current.

Design highlights include:

• Step-lap core structure to reduce no-load losses

• High-strength copper or aluminum windings

• Uniform electric field distribution

• Secure clamping system to withstand short-circuit forces

The optimized core and winding design contributes to efficient energy transfer and mechanical durability.

Oil-Immersed Insulation System

Transformer oil plays a critical role in the S9 type power transformer.

Functions of the oil include:

• Electrical insulation between live parts

• Effective heat dissipation from windings and core

• Protection against moisture and oxidation

The oil tank is sealed or conservator-type, ensuring stable oil quality and long service life.

Cooling Method

The standard cooling method for the S9 type oil-immersed power transformer of 35 kV is ONAN (Oil Natural Air Natural).

Cooling system advantages:

• Simple and reliable structure

• No external power required

• Stable temperature control under normal operating conditions

For higher capacity transformers, forced cooling options can be provided if required.

Electrical Performance

The S9 type transformer is designed to meet distribution system requirements at the 35 kV voltage level.

Performance features include:

• Stable voltage regulation

• Acceptable no-load and load losses

• High insulation reliability

• Strong overload capability within specified limits

These characteristics ensure consistent and safe power supply.

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Safety and Environmental Considerations

Although oil-immersed transformers involve flammable insulating oil, the S9 series incorporates multiple safety measures.

Safety considerations include:

• Robust tank design to prevent oil leakage

• Pressure relief devices

• Reliable sealing structure

• Optional fire-protection accessories

Proper installation and maintenance significantly reduce environmental and fire risks.

Typical Applications

The S9 type oil-immersed power transformer of 35 kV is widely used in:

• 35 kV substations

• Industrial power distribution systems

• Mining and heavy industry facilities

• Rural and urban power networks

• Power plants and grid interconnection points

Its adaptability makes it suitable for both indoor and outdoor installations.

Installation and Maintenance

Oil-immersed transformers require regular inspection to ensure safe operation.

Maintenance highlights:

• Periodic oil testing and filtration

• Inspection of bushings and seals

• Monitoring of oil temperature and oil level

• Routine electrical testing

With proper maintenance, the S9 type transformer can achieve a long service life.

Standards and Compliance

The S9 type oil-immersed power transformer of 35 kV is manufactured and tested in accordance with relevant national and international standards for power transformers.

Compliance ensures:

• Electrical safety and performance consistency

• Compatibility with grid requirements

• Reliable operation under rated conditions

Conclusion

The S9 type oil-immersed power transformer of 35 kV remains a dependable and cost-effective solution for high-voltage distribution systems. Its mature design, strong insulation capability, and stable cooling performance make it suitable for a wide range of utility and industrial applications.

For projects where reliability, proven technology, and long service life are priorities, the S9 series continues to be a trusted choice.