An on-load tap changer has a contact system. The contact system includes: a fixed contact; a movable contact; and an auxiliary contact. The moveable contact is configured to directly contact, in a stationary state, the fixed contact. The auxiliary contact is configured to electrically connect, in addition to the direct contact, the movable contact with the fixed contact in the stationary state. The auxiliary contact is constructed and arranged to conduct a current between the fixed contact and the movable contact in the event of interruption of the direct contacting.

A contact device includes a moving contactor, a pair of moving contacts arranged in one direction, a pair of fixed terminals, and a pair of fixed contacts. At least one fixed terminal, selected from the pair of fixed terminals, includes a contact holder. The contact holder includes a first fixed extension and a second fixed extension. As for either a current component flowing in the one direction into the fixed contact or a current component flowing in the one direction out of the fixed contact, the current component flowing through the first fixed extension has a larger amount of current than a current component flowing through the second fixed extension.

An electric switch including a frame, a first stationary contact, a roll element adapted to rotate relative to the frame, a rotating contact stationary fixed to the roll element, and an arc extinguisher plate system. The arc extinguisher plate system includes at least one first arc extinguisher plate for extinguishing an electric arc generated during an opening event between the first stationary contact and a first contact portion of the rotating contact. The at least one first arc extinguisher plate is fixed to the roll element.

An electric switch including a frame, a first stationary contact, a roll element adapted to rotate relative to the frame, a rotating contact stationary fixed to the roll element, and an arc extinguisher plate system. The arc extinguisher plate system includes at least one first arc extinguisher plate for extinguishing an electric arc generated during an opening event between the first stationary contact and a first contact portion of the rotating contact. The at least one first arc extinguisher plate is fixed to the roll element.

An on-load tap changer has a contact system. The contact system includes: a fixed contact; a movable contact; and an auxiliary contact. The moveable contact is configured to directly contact, in a stationary state, the fixed contact. The auxiliary contact is configured to electrically connect, in addition to the direct contact, the movable contact with the fixed contact in the stationary state. The auxiliary contact is constructed and arranged to conduct a current between the fixed contact and the movable contact in the event of interruption of the direct contacting.

A gas circuit breaker includes: a fixed arc contact extending along an operating axis; a moving arc contact allowed to move to a position where the moving arc contact contacts the fixed arc contact and a position where the moving arc contact is separated from the fixed arc contact; a frame forming a puffer chamber around the moving arc contact; a nozzle having a cylindrical shape centered on the operating axis, the nozzle being fixed to the frame and projecting in a direction toward the fixed arc contact from the moving arc contact; and an arc extinction assisting portion provided on an inner surface of the nozzle and made of an ablation material. The nozzle and the arc extinction assisting portion are provided with a fall-off preventing portion to prevent the arc extinction assisting portion from falling off the nozzle.

A contact device includes a moving contactor, a pair of moving contacts arranged in one direction, a pair of fixed terminals, and a pair of fixed contacts. At least one fixed terminal, selected from the pair of fixed terminals, includes a contact holder. The contact holder includes a first fixed extension and a second fixed extension. As for either a current component flowing in the one direction into the fixed contact or a current component flowing in the one direction out of the fixed contact, the current component flowing through the first fixed extension has a larger amount of current than a current component flowing through the second fixed extension.

A gas circuit breaker includes: a fixed arc contact extending along an operating axis; a moving arc contact allowed to move to a position where the moving arc contact contacts the fixed arc contact and a position where the moving arc contact is separated from the fixed arc contact; a frame forming a puffer chamber around the moving arc contact; a nozzle having a cylindrical shape centered on the operating axis, the nozzle being fixed to the frame and projecting in a direction toward the fixed arc contact from the moving arc contact; and an arc extinction assisting portion provided on an inner surface of the nozzle and made of an ablation material. The nozzle and the arc extinction assisting portion are provided with a fall-off preventing portion to prevent the arc extinction assisting portion from falling off the nozzle.

Disclosed are an arc extinguishing unit and an air circuit breaker comprising the same. The present disclosure provides an arc extinguishing unit, 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 from both ends in the width direction so that an induced magnetic field can be formed by an arc generated when a fixed contact and a movable contact are spaced apart.

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.