High-voltage circuit breakers have greatly changed since they were first introduced in the mid-1950s, and several interrupting principles have been developed that have contributed successively to a large reduction of the operating energy. These breakers are available for indoor or outdoor applications, the latter being in the form of breaker poles housed in ceramic insulators mounted on a structure.

Current interruption in a high-voltage circuit breaker is obtained by separating two contacts in a medium, such as sulphur hexafluoride (SF6), having excellent dielectric and arc-quenching properties. After contact separation, current is carried through an arc and is interrupted when this arc is cooled by a gas blast of sufficient intensity.