What are the leading transformer insulating oil companies in India?

The leading transformer insulating oil companies in India include Indian Oil Corporation Limited (IOCL), Bharat Petroleum Corporation Limited (BPCL), and Hindustan Petroleum Corporation Limited (HPCL). These companies are recognized for their production of high-quality transformer insulating oil, which is essential for the efficient operation and longevity of power transformers. Their products meet international standards and are widely used in the electrical industry across the country.