which oil is used in transformer for cooling?

For cooling purposes, refined mineral oil is commonly used due to its effective thermal conductivity along with its insulating properties; synthetic or ester-based oils are alternatives in specific applications.

Is transformer oil toxic?

Transformer oil, primarily mineral oil, is generally considered non-toxic but can be harmful if ingested or if it comes into prolonged contact with skin. However, some synthetic and ester-based transformer oils may have different toxicity profiles. Always follow safety guidelines and consult the Material Safety Data Sheet (MSDS) for specific information on handling and potential hazards.