Multiphase gas expansion circuit breaker for gas-insulated metalclad cell

Claim 1

A multiphase electrical gas expansion circuit breaker having a plurality of arc extinguishing chambers arranged parallel to one another side by side in a cubicle with a sealed enclosure filled with a high dielectric strength gas, the arc extinguishing chamber of each pole comprising: a closed housing in which a gas pressure rise takes place due to the action of the arc, a pair of separable aligned stationary and movable contacts extending in the direction of the longitudinal axis of the housing, at least one of said contacts being hollow to ensure communication between the closed housing of each pole and of the enclosure, which forms an expansion volume for the gas extinguishing chamber, a metal shielding wall arranged in the housing of each chamber so as to counteract the influence of the magnetic stray fields of the adjacent poles liable to cause radial displacement of the arc in a direction perpendicular to the longitudinal axis, said wall having a lateral revolution surface ensuring centering of the arc to favor outflow of the gas towards said expansion volume through the hollow contact, an annular electrode electrically connected to the stationary contact and coaxially surrounded by said shielding wall, and magnetic arc rotating means for causing the arc to rotate on a track of said annular electrode, said means including an electromagnetic coil or a hollow permanent magnet, located in each arc extinguishing chamber.