In power systems, transformers play a critical role in voltage conversion and power distribution. Among them, oil-immersed transformers stand out for their excellent heat dissipation, high overload capacity, and environmental adaptability. They are widely used in substations, industrial and mining enterprises, renewable energy projects, and outdoor distribution networks. As a professional electrical equipment supplier, Haiyifeng is committed to delivering high-performance, highly reliable oil-immersed transformer solutions to support global power infrastructure development.
1. Working Principle and Structure of Oil-Immersed Transformers
Oil-immersed transformers use insulating oil as the primary insulation and cooling medium. Their core components include:
Core: Made of high-permeability silicon steel sheets to reduce hysteresis and eddy current losses.
Windings: High- and low-voltage coils wound with copper or aluminum conductors to achieve voltage transformation.
Insulating Oil: Provides insulation, heat dissipation, and arc quenching. Mineral oil or natural ester oil is commonly used.
Tank: A sealed structure that protects internal components from moisture and contaminants.
Accessories: Oil level gauge, thermometer, pressure relief valve, tap changer, etc.
During operation, heat generated by the windings and core is transferred through the insulating oil to the tank wall and cooling fins, where natural or forced air cooling dissipates the heat into the surrounding environment, ensuring long-term stable operation.
2. Key Advantages of Oil-Immersed Transformers
Compared with dry-type transformers, oil-immersed transformers offer the following advantages:
High heat dissipation efficiency: The high thermal conductivity of insulating oil, combined with fin-type radiators or corrugated tanks, allows the transformer to withstand significant load fluctuations.
Strong overload capability: The thermal capacity of the oil buffers temperature rise during short-term overloads, making it suitable for seasonal load variations.
Good environmental adaptability: The fully sealed tank prevents dust and moisture ingress, making it suitable for outdoor installation (with proper protection).
Excellent economy: Lower manufacturing cost for the same capacity, long maintenance intervals, and a clear life-cycle cost advantage.
Recyclability: Insulating oil can be reconditioned or biodegraded (e.g., natural ester oil), aligning with environmental trends.
3. Typical Applications
Haiyifeng oil-immersed transformers are widely used in the following fields:
Power systems: Distribution substations, switching stations, rural grid upgrades.
Industrial manufacturing: Power supply for high-energy-consumption plants such as steel, chemical, and cement.
Renewable energy: Step-up transformers for photovoltaic power plants and wind farms.
Infrastructure construction: Auxiliary power supply for airports, ports, tunnels, and subways.
Overseas projects: Customized products for high-temperature, high-humidity, high-altitude, or other special environments.
4. Reliability and Maintenance Considerations
To ensure long-term safe operation of oil-immersed transformers, attention should be paid to:
Regular oil sampling and testing: Analyze breakdown voltage, dielectric loss factor, moisture content, and dissolved gases (DGA) to predict internal faults.
Oil level and temperature monitoring: Equip with oil level gauges and temperature controllers to avoid oil shortage or overheating.
Leak-proof design: Use high-quality welding processes and gaskets to ensure environmental compliance.
Overvoltage protection: Equip with surge arresters and neutral grounding devices.
Haiyifeng transformers are designed in strict accordance with IEC 60076, GB 1094 and other standards. Optional intelligent monitoring terminals enable remote real-time warning of temperature rise, load, and oil pressure, reducing operation and maintenance costs.
5. Why Choose Haiyifeng?
Mature technology: Years of experience in transformer R&D and manufacturing; products certified by CE, UL, KEMA, etc.
Flexible customization: Support for non‑standard customization of voltage levels (10kV–35kV), capacities (50kVA–10MVA), vector groups, and on‑load/off‑load tap changers.
Quality assurance: Fully automated production lines; each transformer undergoes full tests including induced overvoltage withstand, partial discharge, and temperature rise before delivery.
Global service: On-site installation guidance, technical training, and fast spare parts supply with prompt response.
6. Conclusion
Oil-immersed transformers have proven their reliability and economy through decades of operation as a backbone of power networks. Haiyifeng will continue to improve product energy efficiency and environmental performance, providing safe and intelligent power distribution solutions to our customers. For detailed technical specifications or a quotation, please contact our technical team.
In power transformer applications, selecting the right cooling method is critical for efficiency, lifespan, and operational safety. Among the most widely used transformer cooling systems are ONAN and ONAF cooling methods. Understanding the differences between these two systems helps utilities, industrial plants, and electrical engineers choose the best transformer solution for their projects.
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Hot spot temperature is one of the most critical factors affecting the lifespan, efficiency, and operational safety of oil immersed transformers. Excessive hot spot temperatures accelerate insulation aging, reduce transformer reliability, and increase the risk of unexpected failures. For industries relying on continuous power supply, maintaining optimal transformer temperature is essential for long-term performance.Modern power systems widely use both ONAN transformer and ONAF transformer cooling methods to control internal heat generation and improve transformer stability. As a professional transformer manufacturer, Qingdao Haiyifeng Industry and Trade designs and manufactures high-efficiency oil immersed transformers engineered for superior thermal performance and lower hot spot temperatures.According to recent 2026 SEO and AI-search optimization trends, structured technical content with direct answers, practical solutions, and clear engineering explanations performs best for both Google Search and AI-driven search engines.
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