Gas circuit breakers are automatically operated high voltage electrical switches designed to protect high voltage electrical circuits from damage caused by overload or short circuit. The basic function is to detect a fault condition and interrupt current flow in high voltage electrical power transmission networks of 72.5 kV or higher. Sulfur hexafluoride (SF6) is an excellent gaseous dielectric for high voltage power applications and is used extensively in high voltage circuit breakers and other switchgear employed by the power industry. Applications include transmission lines and power distribution substations. The outstanding properties of SF6 gas that makes its use in high voltage applications desirable are high dielectric strength and a unique arc-quenching ability.