Gaseous Insulation Materials
- Air: Very low cost with stable insulation properties; widely used for insulation gaps in overhead transmission lines and conventional switchgear.
- Sulfur Hexafluoride (SF₆): Possesses an insulation strength 2–3 times that of air and offers arc-extinguishing capabilities; commonly used in high-voltage gas-insulated switchgear (GIS), gas-insulated transformers, and similar equipment.
- Other Gases: Nitrogen, sulfur dioxide, etc.; used in specific sealed electrical equipment to provide insulation and prevent oxidation.
Liquid Insulation Materials
- Mineral Insulating Oil: Exemplified by transformer oil; offers excellent insulation and heat dissipation properties, serving as the primary insulation and cooling medium for transformers, power cables, and capacitors.
- Synthetic Insulating Oil: Such as silicone oil; characterized by high chemical stability and a wide operating temperature range, making it suitable for specialized electrical equipment with demanding operating conditions.
- Natural Vegetable Oil: Such as castor oil; environmentally friendly and biodegradable, increasingly used in eco-friendly distribution transformers.