Oil-Immersed Transformers: Core Equipment and Technical Analysis of Power Systems

I. Core Advantages of Oil-Immersed Transformers

As one of the most critical equipment in power systems, oil-immersed transformers dominate the power transmission and distribution field due to their unique design and exceptional performance. Compared to dry-type transformers, oil-immersed transformers offer the following significant advantages:

1. Excellent Insulation Performance: High-quality transformer oil is used as the insulating medium, with a dielectric strength of 40-50 kV/mm, far exceeding that of air.
2. Outstanding Heat Dissipation Efficiency: The thermal capacity of transformer oil is five times that of air, effectively dissipating heat generated during operation.
3. Strong Overload Capacity: Can withstand 150% of rated capacity for short periods.
4. Long Service Life: Designed for a service life of over 40 years, extendable with proper maintenance.
5. Cost-Effectiveness: 20-30% lower manufacturing cost compared to dry-type transformers of the same capacity.

II. Key Technical Features

Insulation System:

• Composite insulation system consisting of transformer oil and insulating paper.
• Dielectric strength up to 80-100 kV/mm.
• Multi-layer barrier insulation structure.

Cooling System:

• ONAN (Oil Natural Air Natural) cooling.
• ONAF (Oil Natural Air Forced) cooling.
• OFAF (Oil Forced Air Forced) cooling.

Protection System:

• Gas protection device.
• Pressure relief device.
• Temperature monitoring system.
• Oil level indicator.

III. Application Fields

Oil-immersed transformers are widely used in:

1. Power Plants: Step-up transformers to elevate generator output voltage to transmission levels.
2. Substations: Main transformers for converting different voltage levels.
3. Industrial and Mining Enterprises: Distribution transformers for powering production equipment.
4. New Energy Sector: Step-up transformers for wind farms and photovoltaic power stations.

IV. Operation and Maintenance Essentials

Daily Inspections:

• Check the oil level and temperature of oil-immersed transformers.
• Listen for abnormal operating sounds.
• Inspect for oil leaks.

Regular Testing:

• Transformer oil analysis (annually).
• Insulation resistance testing (every six months).
• Winding DC resistance testing (annually).

Fault Handling:

• Measures for abnormal oil temperature rise.
• Emergency response to gas protection activation.
• Methods for repairing oil leakage faults.

V. Technological Innovations and Development Trends

Environmentally Friendly Oil-Immersed Transformers:

• Use of biodegradable transformer oil.
• Noise control technology (<55 dB).
• Energy-saving design (30% reduction in no-load losses).

Smart Oil-Immersed Transformers:

• Online monitoring systems.
• Fault预警功能 (early warning功能).
• Remote control systems.

New Material Applications:

• Amorphous alloy cores.
• High-temperature resistant insulating materials.
• Environmentally friendly transformer oil.

VI. Selection Considerations

When selecting oil-immersed transformers, consider:

1. Rated capacity and voltage level.
2. Installation environmental conditions.
3. Load characteristic requirements.
4. Protection level requirements.
5. Energy efficiency standard requirements.

VII. Safe Operation Guidelines

Oil-immersed transformer operation must adhere to:

1. Strict implementation of operating procedures.
2. Regular preventive testing.
3. Complete fire protection facility configuration.
4. Establishment of emergency plans.
5. Maintenance of operational records.

Conclusion

As a vital component of power systems, the technical level and operational reliability of oil-immersed transformers directly impact the safety and stability of the power grid. With the continuous application of new technologies and materials, oil-immersed transformers are evolving toward higher efficiency, environmental friendliness, and intelligence, continuing to provide essential support for the development of the power industry.