What specifications should oil for transformers meet?

Oil for transformers should meet several key specifications to ensure optimal performance and safety. It must have a high dielectric strength, typically above 30 kV, to prevent electrical breakdown. Additionally, the oil should have low viscosity for efficient heat transfer, a high flash point (above 140°C) for fire safety, and excellent oxidation stability to prolong service life. Furthermore, it should be free of impurities and meet standards such as ASTM D3487 or IEC 60296 for mineral insulating oils.