Circuit breaker with combined magnetic and pneumatic arc quenching - uses magnetic coil for arc rotation and conductive screen preventing pre-ionisation of expansion gas

摘要

The multipolar circuit breaker has a sealed envelope for each pole filled with a gas exhibiting a high dielectric strength, e.g. SF6, and sub-divided into a breaker chamber (8) and an expansion chamber (10). A tubular movable contact (9) passes through the internal partition (2) and has an escape opening (11) allowing the interior (9a) of this contact (9) to communicate with the expansion chamber (10). The breaker chamber (8) has a fixed contact (5) cooperating with the movable tubular contact (9). A magnetic coil (6) surrounds the fixed contact (5) to provide an arc quenching field causing rotation of the arc (13). The movable contact (9) is enclosed by a conductive partition (2) and the fixed contact (5) for preventing preionisation of the gas during thermal expansion within the breaker chamber (8).