Cooling Methods of Oil Immersed Transformer
Oil-immersed transformers play an irreplaceable role in the power grid due to their superior insulation and heat dissipation performance. However, transformers continuously generate heat during high-efficiency operation. How to effectively "cool" them to ensure long-term stable and reliable operation has become a sophisticated engineering technology. Today, we will delve into the four mainstream cooling methods for oil-immersed transformers, revealing the secrets behind their efficient heat dissipation.
Common cooling methods for transformers include:
1. Oil-immersed self-cooling (ONAN): Oil-immersed transformers are cooled through the natural circulation of oil. Heat is dissipated to the surrounding air through heat sinks. This method is suitable for small and medium-sized distribution transformers.
2. Oil-immersed air cooling (ONAF): Cooling is achieved by forced airflow through a fan. When the top oil temperature or load current reaches a set value, the fan automatically starts, forcibly blowing air onto the radiator. This method is suitable for medium and large-sized transformers.
3. Forced Oil Circulation Air Cooling (OFAF): An oil pump is added to the oil circuit, forcing the transformer oil to flow rapidly along a set path, while a fan runs at full capacity for cooling. The oil circulation speed no longer depends on natural temperature difference, but is dominated by the oil pump. Commonly found in main transformers of large power plants, ultra-high voltage substations, and other critical power nodes.
4. Forced Oil Circulation Water Cooling (OFWF): An oil pump forces oil circulation. Instead of being sent to an air-cooled radiator, the hot oil flows through a device called an "oil-water heat exchanger." In this device, the hot oil flowing inside the pipes transfers heat to the cooling water flowing outside, which then carries the heat away. OFWF offers extremely high cooling efficiency for indoor installations or special applications with abundant water resources but limited space.