What type of gas fills an SF6 bushing?

The correct choice is SF6, which stands for sulfur hexafluoride. This gas is specifically used in bushings, such as those found in electrical applications, due to its excellent insulating properties and ability to prevent electrical discharges. SF6 is a colorless, odorless gas that is much denser than air, which enhances its effectiveness in insulating high-voltage electrical equipment and minimizing the risk of arcing. Its chemical stability also contributes to its suitability for use in various industrial applications.

Other gases, such as carbon dioxide, nitrogen, and argon, do not possess the same insulating properties as SF6, making them less effective for this purpose in electrical equipment. Each of those alternatives has its applications; for example, nitrogen is often used in inert gas applications but does not provide the same level of insulation in high-voltage scenarios. Therefore, SF6 is the optimal choice for filling bushings in electrical equipment.