Disclosed are an arc extinguishing unit and an air circuit breaker comprising the same. An arc extinguishing unit according to an embodiment of the present invention provides: side plates spaced apart from each other and disposed to face each other; a plurality of grids disposed between the side plates, spaced apart from each other, and coupled to the side plates, respectively; a magnet unit forming a magnetic field for changing a path of an arc formed between a fixed contact and a movable contact disposed to be spaced apart from the fixed contact, and disposed adjacent to the outermost grid adjacent to the fixed contact among the plurality of grids.

An arc plate for a circuit breaker includes a body and a magnetic coating that covers an exterior of the body. The magnetic coating is a metal matrix composite including from 80 to 92 volume percentage of a metal that is magnetic, and from 8 to 20 volume percentage of particles. The particles have a higher melting temperature than the metal.

An arc quenching device for a three-phase electrical switchgear. The device includes a first busbar, a second busbar and a third busbar, each of a respective phase of the three-phase switchgear. The device also includes a first piston and a second piston, each of an electrically conductive material. The device also includes at least one pyrotechnical actuator arranged with the first and second pistons to axially move each of the first and second pistons if the at least one pyrotechnical actuator is fired. The first and second pistons are arranged in relation to the first, second and third busbars such that said axial movement brings the first piston into contact with both the first busbar and the second busbar, and the second piston into contact with both the first busbar and the third busbar.

Disclosed are an arc extinguishing unit, a circuit breaking unit, and an air circuit breaker including the same. The present disclosure provides an arc extinguishing unit, a circuit breaking unit, and an air circuit breaker, including: side plates spaced apart from each other and disposed to face each other; a plurality of grids disposed between the side plates, spaced apart from each other, and coupled to the side plates, respectively; and a grid cover located above the grid and covering the grid, wherein the grid includes a grid leg extending downward to surround from both sides a protruding contact disposed to extend upward from a movable contact; and a first protective part formed to surround at least a portion of the grid leg at a lower portion of the grid leg.