High temperature oilimmersed transformers are a type of oilimmersed transformer that uses special hightemperature resistant insulating oil and insulation materials, which can adapt to higher operating temperatures than conventional oilimmersed transformers. The core related parameters and characteristics are as follows:

　　1. Insulation system and temperature level

　　The insulation level is mainly determined by the insulating oil and the insulating materials used in the winding:

　　Common hightemperature insulating oils include hightemperature naphthenic insulating oil (allowable operating temperature up to 120℃), silicone insulating oil (allowable operating temperature up to 180℃), and ester insulating oil (including synthetic ester and natural ester, allowable operating temperature up to 150℃180℃)

　　The matching winding insulation materials are mostly Class F, Class H or even higher level insulation materials, corresponding to the maximum allowable winding hot spot temperature of 155℃, 180℃ or higher

　　The allowable temperature rise (based on the ambient temperature of 40℃) is generally 100K140K, which is higher than the 65K80K of conventional oilimmersed transformers

　　2. Core advantages

　　Stronger high temperature resistance: It can operate stably in the environment with higher ambient temperature, or bear higher overload for a short time

　　Longer service life: Under the same working conditions, the insulation material and insulating oil with higher temperature resistance have slower aging speed

　　Better safety: Most hightemperature insulating oils have better fire resistance (such as ester insulating oil is fireresistant, and silicone insulating oil is noncombustible)

　　3. Applicable scenarios

　　Industrial sites with high ambient temperature, such as steel plants, cement plants, hightemperature processing workshops

　　Scenarios that need to bear frequent or longterm overload, such as some temporary power supply sites, or power supply nodes with large load fluctuations

　　Scenarios with high requirements for fire safety, such as highrise buildings, underground engineering, and densely populated places