Patent ID: 7595461

Claim:
A heavy-duty circuit-breaker having an axis (A) which defines an axial coordinate (z) parallel to the axis and a radial coordinate (r) at right angles to the axis, and having an arcing contact piece, a current-carrying element and an erosion protection element, with the arcing contact piece having an opening in order to carry a substantially axial flow of a gas which has been heated by an arc which may be based on the arcing contact piece, and together with the current-carrying element forms a flat contact surface (F) in order to carry a short-circuit current (I) which flows through the arcing contact piece and the current-carrying element for the time during which the arc burns, and with the erosion protection element substantially shielding the current-carrying element from the flow close to the flat contact (F), and with the current-carrying element having an axial area in which a radial internal dimension (d 2 ) of the current-carrying element increases in steps or continuously as the distance from the flat contact (F), measured parallel to the axis (A), increases, wherein the axial area is intended to hold the erosion protection element, wherein a radial external dimension (D 3 ) of the erosion protection element is matched to the radial internal dimension (d 2 ) of the current-carrying element in the axial area, with the erosion protection element being radially adjacently fitted into the current-carrying element, wherein the erosion protection element extends from a region of the flat contact surface in an axial direction of the current-carrying element opposite the arcing contact piece.