What are the specifications for transformer insulating oil?

The specifications for transformer insulating oil include a minimum breakdown voltage of 30 kV, a flash point above 140°C, and a viscosity of 20-100 cSt at 40°C. Additionally, the oil should have a low water content (typically below 0.1%), a high oxidation stability, and a dielectric dissipation factor (tan ?) of less than 0.01 at 90°C. These properties ensure effective insulation and cooling in power transformers.