The non-enclosed H-class three-phase dry power transformer has the advantages of being safe, reliable, energy-saving, fire-proof, not producing harmful gases, not polluting the environment, and simple maintenance. Its design is advanced, structure is reasonable, and appearance is beautiful. The main performance index is better than the domestic standard, and the electrical and mechanical performance remains excellent throughout the service life. It is suitable for environments with high fire protection requirements, large load fluctuations, and dirty and humid environments, such as high-rise buildings, airports, docks, subways, hospitals, power plants, metallurgical industries, shopping malls, nuclear power plants, and nuclear submarines.