Single-pole switching unit and switching unit comprising one such unit

A single-pole switching unit having a housing comprising:

• a moving contact bridge;
• a pair of fixed contacts cooperating with the moving contact bridge and respectively connected to a current intake conductor;
• and
• two arc cutoff chambers respectively opening onto an opening volume of the moving contact bridge, each arc cutoff chamber being connected to at least one exhaust channel;
• the at least one exhaust channel comprising a rotating gate designed to be rotated around an axis substantially perpendicular to the exhaust channel by a passage of cutoff gases, a rotation of the rotating gate from a first obstruction position to a second triggering position being designed to actuate a triggering device to cause an opening of the moving contact bridge, the rotation of the rotating gate being defined by an angle of rotation, comprised between an initial angle value in the first obstruction position and a final angle value,
• wherein the rotating gate comprises one edge positioned across from an inner wall of the exhaust channel, in the first obstruction position, the edge being positioned at a first distance from the inner wall of the exhaust channel in the first obstruction position, the edge being movable away from the inner wall of the exhaust channel during the rotation of the rotating gate, a position of the rotating gate defining at least one gas passage section,
• an arrangement of the rotating gate and the inner wall is such that a distance between the edge and the inner wall remains constant and equal to the first distance up to a first threshold value of the angle of rotation of the rotating gate, then increases linearly up to a second threshold value of the angle of rotation of the rotating gate corresponding to a complete opening of the exhaust channel, the first threshold value of the angle of rotation being smaller than the second threshold value of the angle of rotation of the rotating gate so as to ensure a quick cutoff triggering.