A multi-finger electrical contact assembly having unequal electrical resistance in current paths through each finger providing relatively high current withstand capability. The multi-finger electrical contact assembly includes three or more fingers each with a coupled conductor, wherein one or more outer fingers and coupled conductor of the assembly have greater electrical resistance than an inner finger and coupled conductor. Multi-phase circuit breakers including the multi-finger electrical contact assembly and methods are provided, as are other aspects.

Circuit breakers are configured with line terminal geometry that drives the current from a terminal input in a direction that can reduce electromagnetic forces and that can also or alternatively include an arc chute assembly that can reduce repulsive electromagnetic forces to improve the operating level of withstand current (Icw).

Circuit breakers are configured with line terminal geometry that drives the current from a terminal input in a direction that can reduce electromagnetic forces and that can also or alternatively include an arc chute assembly that can reduce repulsive electromagnetic forces to improve the operating level of withstand current (Icw).

A method for determining contact thickness change in a contactor includes sensing a first displacement distance moved by an armature of the contactor from a reference location to a first transition point during a switch-off operation of the contactor at a first contactor life reference time when movable contacts and fixed contacts of the contactor define a first contact thickness. The method further includes sensing a second displacement distance moved by the armature from the reference location to a second transition point during a switch-off operation at a second contactor life reference time that is after the first contactor life reference time when the movable and fixed contacts define a second contact thickness that is less than the first contact thickness. The first displacement distance and the second displacement distance are used to determine a contact thickness change between the first contact thickness and the second contact thickness. A contactor adapted to implement the method is also disclosed.

A circuit interrupter includes a stationary contact and a moveable contact arm assembly having a moveable contact positioned thereon, the moveable contact configured to be moveable into and out of physical contact with the stationary contact. The circuit interrupter also includes an overcurrent tripping device coupled to the moveable contact arm assembly via a linkage assembly and configured to move the moveable contact out of physical contact with the stationary contact upon detection of an overcurrent situation. The moveable contact arm assembly is connected to the linkage assembly via at least two pivots positioned on the contact arm assembly, so as to cause a relative sliding action between the moveable and stationary contacts as the moveable and stationary contacts are moved into or out of contact with each other such that a wiping action is created in order to clean the moveable and stationary contacts.

A circuit interrupter includes a stationary contact and a moveable contact arm assembly having a moveable contact positioned thereon, the moveable contact configured to be moveable into and out of physical contact with the stationary contact. The circuit interrupter also includes an overcurrent tripping device coupled to the moveable contact arm assembly via a linkage assembly and configured to move the moveable contact out of physical contact with the stationary contact upon detection of an overcurrent situation. The moveable contact arm assembly is connected to the linkage assembly via at least two pivots positioned on the contact arm assembly, so as to cause a relative sliding action between the moveable and stationary contacts as the moveable and stationary contacts are moved into or out of contact with each other such that a wiping action is created in order to clean the moveable and stationary contacts.

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.

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.

A circuit breaker comprises a contact and a line terminal configured that are bound in an assembly using a silver nanoparticles (NpAg) material that is synthesized by reducing a precursor salt in presence of a reducing agent. The contact comprises a silver alloy material having a first surface. The line terminal comprises a non-ferrous material having a second surface such that a plurality of drops of the silver nanoparticles (NpAg) material synthesized using a green chemistry process are applied in an interface between the first surface of the contact and the second surface of the line terminal by performing a resistance projection welding to bind the two components.

An interrupter system includes a first coil and an interrupter electrically connected to the first coil. The interrupter includes: a first terminal; a second terminal electrically connected to the first terminal; a third terminal electrically separated from the first terminal and the second terminal; a heat generating element electrically connected to the third terminal; and an explosive configured to be ignited by the heat generating element to produce a gas for interrupting an electrical connection between the first terminal and the second terminal. The first coil is electrically connected to the heat generating element via the third terminal. Moreover, the first coil is configured to, when an abnormal current flows between the first terminal and the second terminal, generate an electric power for igniting the explosive from the abnormal current.