The typical service life standard for oil-immersed transformers generally ranges from 20 to 40 years, influenced by factors such as design life, operating temperature, load conditions, and maintenance practices. Below is a detailed analysis:

　　From a design perspective, the general design life of an oil-immersed transformer is usually 30 years, which is the expected service life under ideal design, manufacturing, and operating conditions. However, in actual operation, due to the effects of insulation material aging, operating temperature, load conditions, maintenance, and other factors, the actual service life typically ranges from 20 to 40 years.

　　Operating temperature is one of the key factors affecting the service life of an oil-immersed transformer. Generally, the higher the temperature that the insulation is subjected to during transformer operation, the faster the insulation will age. Studies have shown that if the temperature at the hottest spot of the transformer windings remains at 95°C, the transformer can operate continuously for 20 years; if the winding temperature rises to 105°C, the service life is reduced to 7.5 years; and if the winding temperature rises to 120°C, the service life is reduced to 2.3 years. Therefore, controlling the operating temperature of the transformer is crucial for extending its service life.

　　Load conditions also affect the service life of an oil-immersed transformer. Long-term overload operation will accelerate the aging process of the transformer and shorten its service life. Therefore, it is important to reasonably control the load of the transformer during operation to avoid long-term overload conditions.

　　Maintenance and upkeep are also significant factors influencing the service life of an oil-immersed transformer. Regular inspection, maintenance, and upkeep of the transformer, timely identification, and handling of potential issues can effectively extend its service life. For example, regularly checking the oil level, oil temperature, and insulation condition of the transformer, and promptly replacing aged insulation materials and transformer oil, etc.