What is the grade of HT transformer oil used in power transformers?

The grade of HT transformer oil used in power transformers is typically classified as mineral oil with specific properties to ensure optimal performance. This oil must meet standards such as IEC 60296, which specifies requirements for electrical insulating oils. HT transformer oil is characterized by high dielectric strength, low viscosity, and excellent thermal stability, making it suitable for high-voltage applications in power transformers.