The present disclosure relates to an arc extinguishing unit of a molded case circuit breaker and, more specifically to an arc extinguishing unit of a molded case circuit breaker, having improved arc elongation performance. The arc extinguishing unit of a molded case circuit breaker, according to one embodiment of the present disclosure, comprises: a first side plate and a second side plate arranged to be spaced a predetermined distance apart from each other; a plurality of grids arranged by predetermined intervals between the first side plate and the second side plate; and an insulation member arranged to adjoin each of the plurality of grids.

A slot motor apparatus for a circuit breaker is disclosed. The slot motor has first and second legs connected by a thin web, and an extending portion extending rearward from the rear faces of the legs. Slot motor-arc plate assemblies having an arc plate assembly received at least partially overtop of the extending portion are also disclosed, as are assemblies having the arc plate assembly received very close to the rear faces of the slot motor legs. Circuit breakers, slot motor-arc plate assemblies, slot motor covers, and methods of operating the slot motor-arc plate assemblies are disclosed, as are other aspects.

A switch capable of withstanding short-circuit currents without being destroyed or deteriorated by the passage of such high currents includes at least one fixed contact and at least one movable contact, wherein the movable contact is displaceable between a closed position of the switch in which the fixed and the movable contacts are electrically connected, and an open position of the switch in which the fixed and movable contacts are separated. The switch includes at least one equipotential connecting member electrically connecting the fixed contact and the movable contact in the closed position of the switch, such that the fixed and the movable contacts are at the same electric potential, and wherein at least a part of the equipotential connecting member is pressed against the fixed contact and/or the movable contact in the closed position of the switch.

Disclosed are an arc chute and a load break switch including same. The arc chute can be installed so as to be in close contact with a curved frame part, and comprises: two cover parts which are arranged adjacent to the outer circumference of the frame part and spaced apart from each other, and overlap each other in the axial direction of the frame part; and an arc grid which is located between the two facing cover parts and coupled to each of the two cover parts. Each of the cover parts is configured such that one side in contact with the outer circumference of the frame part has a shape corresponding to the outer circumference of the frame part.

The present invention provides an arc chute, which can be provided to make close contact with a curved frame part, and a load switch comprising same, the arc chute comprising: two cover parts, which are arranged to be adjacent to the outer circumference of a frame part, are spaced apart from each other, and overlap each other in the axial direction of the frame part; and an arc grid which is arranged between the two cover parts so as to be coupled to each of the two cover parts, wherein the cover part is formed in a shape in which one side coming into contact with the outer circumference of the frame part corresponds to the outer circumference of the frame part.

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.