A DC circuit breaker according to various embodiments may comprise: a first terminal unit connected to a power source; and a second terminal unit connected to the first terminal unit and connected to a load, wherein the first terminal unit includes at least a pair of first terminals connected to each other in parallel and connected to the power source, and the second terminal unit includes at least a pair of second terminals corresponding respectively to the first terminals and connected to each other in parallel so as to be connected to the load.

A circuit interrupter includes a fixed terminal, a movable contactor, a moving mechanism, a squib, and accommodation. The fixed terminal includes a fixed contact. The movable contactor includes a movable contact connected to the fixed contact. The moving mechanism is configured to move the movable contactor from a closed position where the movable contact is connected to the fixed contact to an open position where the movable contact is separated from the fixed contact. The squib is configured to generate gas by combustion. The accommodation is for accommodating the fixed contact and the movable contactor. In the circuit interrupter, the gas is introduced into the accommodation.

An electric contact system includes a moving member movable in a vertical direction, a movable contact mounted on and moved with the moving member, a static contact, and an arc extinguishing device including a movable bracket movable in a horizontal direction and an arc extinguishing sheet mounted on and movable with the movable bracket. The movable contact moves between a switch-on position and a switch-off position. When the movable bracket is moved to a first position, the arc extinguishing sheet is moved beyond a contact area between the movable contact and the static contact and allows the movable contact to electrically contact the static contact. When the movable bracket is moved to a second position, the arc extinguishing sheet is moved into the contact area between the movable contact and the static contact to electrically isolate the movable contact from the static contact.

A device for measuring a condition of an electric switch, an electric switch and a method for measuring a condition of an electric switch are disclosed. In an embodiment an apparatus for measuring a state of an electrical switch is configured to tap a voltage at main contacts of the electrical switch.

Embodiments of the disclosure can include systems and methods for limiting transient over-voltages occurring across a circuit breaker. These embodiments include providing a middle tank portion. They further include providing a first portion coupled to a first side of the middle tank portion, and a second portion coupled to a second side of the middle tank portion. They further include providing a first high voltage terminal coupled to the first portion, and a second high voltage terminal coupled to the second portion. They further include providing a post insulator supported and extending from the middle tank portion. They further include providing a first surge arrester connecting the first high voltage terminal to a first connector extending from the post insulator, and a second surge arrester connecting the second high voltage terminal to a second connector extending from the post insulator.

An electrical connection for medium and high voltage switchgears includes an electrical terminal of a switchgear. An electrical contacting surface of the electrical terminal as first current carrying part is electrically connected with a contacting surface of an external electrical connector part as second current carrying part via a connecting system. The connecting system includes a stretch-bolt function, which is integrated in one of the current carrying parts. The stretch bolt function is provided with a male screw thread at the extending end, which is configured to be screwed into a female threaded hole of the second current carrying part.

A progressively contacting switch includes a set of contacts connected to an input. The set includes a first sacrificial contact formed of a first metal and a first conducting contact formed of a second metal. The switch further includes a movable set of contacts connected to an output. The movable set includes a second sacrificial contact formed of the first metal and a second conducting contact formed of the second metal. The switch includes an element configurable to connect the movable set of contacts such that the first sacrificial contact connects to the second sacrificial contact at a first time, thereby causing a current to flow from the input to the output, and while the first sacrificial contact remains connected to the second sacrificial contact, the first conducting contact connects with the second conducting contact at a later time.

A progressively contacting switch includes a set of contacts connected to an input. The set includes a first sacrificial contact formed of a first metal and a first conducting contact formed of a second metal. The switch further includes a movable set of contacts connected to an output. The movable set includes a second sacrificial contact formed of the first metal and a second conducting contact formed of the second metal. The switch includes an element configurable to connect the movable set of contacts such that the first sacrificial contact connects to the second sacrificial contact at a first time, thereby causing a current to flow from the input to the output, and while the first sacrificial contact remains connected to the second sacrificial contact, the first conducting contact connects with the second conducting contact at a later time.

Embodiments of the disclosure can include systems and methods for limiting transient over-voltages occurring across a circuit breaker. These embodiments include providing a middle tank portion. They further include providing a first portion coupled to a first side of the middle tank portion, and a second portion coupled to a second side of the middle tank portion. They further include providing a first high voltage terminal coupled to the first portion, and a second high voltage terminal coupled to the second portion. They further include providing a post insulator supported and extending from the middle tank portion. They further include providing a first surge arrester connecting the first high voltage terminal to a first connector extending from the post insulator, and a second surge arrester connecting the second high voltage terminal to a second connector extending from the post insulator.

An embodiment of the invention relates to a contact pin for an electric switch. The contact pin is designed as a composite support.