The invention concerns a contact arrangement (50) for a Pre-Insertion Resistor (PIR) wherein a control rod (20) is arranged to move a movable contact (30), against the force of a biasing member (18), into temporary connection with a PIR. The control rod (20) comprises a tulip (21) with a plurality of resilient fingers (24) and having a first diameter where it is able to mechanically couple to a latching ring (31) on the movable contact (30), and a second diameter where the tulip (21) is deformed with the fingers (24) deflected inwards, once the resistance to movement exceeds a predetermined value, wherein the latching ring (31) is able to pass over the tulip (21) to decouple the movable contact (30) from the control rod (20). The contact arrangement (50) is particularly suited for a PIR arranged for connection in parallel to the interrupter of a gas-insulated switchgear (GIS) circuit breaker.

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.

A DC high-voltage electrical installation comprises a switching device for switching an electric current in the main circuit, and a method for controlling the closure of a switching device in such an installation. The installation includes a controlled variable resistor system making it possible to modify the resistance value of the resistor system seen by the current flowing through the main electrical circuit. The resistance value takes at least three distinct values: high, a lower value, and at least one nonzero intermediate value comprised between the high value and the low value. The installation includes a coordination device making it possible to control switching times of the resistance values of the resistor system.

An on-load tap changing apparatus includes a first switching unit connected to a first tap of a transformer provided in a power system and switching power supplied from the first tap, a first impedance changing unit connected in series with the first switching unit and increasing an impedance when the first switching unit executes a switching operation, a second switching unit connected to a second tap of the transformer and switching power supplied from the second tap, and a second impedance changing unit connected in series with the second switching unit and increasing an impedance when the second switching unit executes a switching operation. The on-load tap changing apparatus can suppress an arc at the time of switching, reduce deterioration of a switching unit, and have excellent durability.

A circuit breaker system is disclosed in the present application. The circuit breaker system includes a housing to hold an electrical interrupter within an internal region separated from an external ambient region. The electrical interrupter includes at least a first pair of electrical contact elements that are movable between open and closed positions. A voltage limiter, such as a metal oxide varistor (MOV), is connected across the pair of electrical contact elements to receive and dissipate a transient voltage when the first pair of electrical contacts is moved from a closed position to an open position, thereby reducing undesired arcing and premature wear or erosion of certain electrical components.

A switching device includes: two interrupter units connected in series; at least one drive unit for moving at least one contact; and two control capacitors, each of which is connected in parallel with the interrupter units. At least one control capacitor has mechanically movable components for changing the capacitance, and at least one of these components is mechanically coupled to the drive unit.

A gas circuit breaker including: a cylindrical tank; a stator fixed inside the tank; and a mover disposed so as to face the stator. The mover is movable between a closing position and a cutoff position, the mover is in contact with the stator when located in the closing position, and the mover is out of contact with the stator when located in the cutoff position. The stator includes: a stator-side main contact fixed inside the tank; a stator-side resistance contact having a ring shape surrounding the stator-side main contact; and a spring and a dashpot supporting the stator-side resistance contact from a direction opposite to a direction in which the stator-side resistance contact faces the mover. The mover includes: a mover-side main contact disposed so as to face the stator-side main contact; and a mover-side resistance contact disposed in such a way as to face the stator-side resistance contact.

A power switchgear includes: a vacuum switch tube in a ground tank; a movable side conductor which passes through the ground tank to connect to one side of the vacuum switch tube, and extends to the upper side of the tank; a fixed side conductor which passes through the ground tank and connects to another side of the vacuum switch tube, and extends to the upper side of the tank. A conical insulator is placed on an opening of the ground tank, and a tip end is inserted in the ground tank; an insulation cylinder is placed at a rear end of the conical insulator to cover the inside of a concave portion of the conical insulator, and protrudes outside the ground tank; and a surge suppression apparatus inside the insulation cylinder has a terminal in the conical insulator and connected to a main circuit of the vacuum switch tube.

The invention discloses a short circuit current hierarchical control tripping parameter circuit breaker. According to the invention, resistance of an alloy magnetic resistance body is changed through circuit current, and contract control can be carried out on short-circuit current. The control range of the circuit breaker can achieve that no magnetic resistance will be generated when current is no more than 8 times of rated operational current, and current limiting may be realized by the magnetic resistance when current is 8 times more than rated value. In this way, hierarchical control on short-circuit current of different levels of circuits can be carried out, and short-circuit current can be limited in a predetermined range, thereby restricting the short-circuit current in a predetermined range, solving a problem of power supply flickering, and avoiding large-area power failure accidents caused by override trip existing in an electrical control switch.

The invention discloses a short circuit current hierarchical control tripping parameter circuit breaker. According to the invention, resistance of an alloy magnetic resistance body is changed through circuit current, and contract control can be carried out on short-circuit current. The control range of the circuit breaker can achieve that no magnetic resistance will be generated when current is no more than 8 times of rated operational current, and current limiting may be realized by the magnetic resistance when current is 8 times more than rated value. In this way, hierarchical control on short-circuit current of different levels of circuits can be carried out, and short-circuit current can be limited in a predetermined range, thereby restricting the short-circuit current in a predetermined range, solving a problem of power supply flickering, and avoiding large-area power failure accidents caused by override trip existing in an electrical control switch.