An improved circuit breaker is disclosed herein. The improved circuit breaker includes one or more main contacts and only one resistor contact. The only one resistor contact is connected in parallel with at least one of the one or more main contacts.

A circuit breaker having at least one capacitor assembly connected in parallel across a contact of the circuit breaker. The capacitor assembly can be housed with the contact within a sealed enclosure of the circuit breaker. The enclosure can be configured to house an insulating medium that is configured to reduce or quench an arc(s) that may form at least when the contact of the circuit breaker is displaced from a closed position to an open position. The capacitor assembly, which includes a transient recovery voltage (TRV) capacitor, can be configured to delay terminal fault and short line fault TRV and the rate of rise of the initial TRV (ITRV) that can appear across the open contact of the circuit breaker.

A circuit breaker having at least one capacitor assembly connected in parallel across a contact of the circuit breaker. The capacitor assembly can be housed with the contact within a sealed enclosure of the circuit breaker. The enclosure can be configured to house an insulating medium that is configured to reduce or quench an arc(s) that may form at least when the contact of the circuit breaker is displaced from a closed position to an open position. The capacitor assembly, which includes a transient recovery voltage (TRV) capacitor, can be configured to delay terminal fault and short line fault TRV and the rate of rise of the initial TRV (ITRV) that can appear across the open contact of the circuit breaker.

A voltage dividing capacitor (1) arranged parallel to a vacuum interrupter (2) has a long narrow cylindrical-shaped capacitor series (16) that is configured by a plurality of capacitor elements (15) being connected with connecting screws. One end of the capacitor series (16) is supported by a fixed supporting unit (25), and the other end id supported by a movable supporting unit (26) so as to allow thermal expansion and contraction. A insulation tube (31) fixed to the movable supporting unit (26) has a short length, and only a first capacitor element (15A) is fitted into the insulation tube (31). Since a portion where high electric field appears is a middle of five capacitor elements (15) and electric field at an end portion of the capacitor series (16) is low, forming of triple junction at the portion of the high electric field is avoided.

A voltage dividing capacitor (1) arranged parallel to a vacuum interrupter (2) has a long narrow cylindrical-shaped capacitor series (16) that is configured by a plurality of capacitor elements (15) being connected with connecting screws. One end of the capacitor series (16) is supported by a fixed supporting unit (25), and the other end id supported by a movable supporting unit (26) so as to allow thermal expansion and contraction. A insulation tube (31) fixed to the movable supporting unit (26) has a short length, and only a first capacitor element (15A) is fitted into the insulation tube (31). Since a portion where high electric field appears is a middle of five capacitor elements (15) and electric field at an end portion of the capacitor series (16) is low, forming of triple junction at the portion of the high electric field is avoided.

A vacuum capacitor switch with pre-insertion contact includes first and second contact systems. The first contact system includes an annular stationary contact and an annular moving contact retained on a moving contact drive rod. A second contact system includes a moving contact retained on an end of the moving contact drive rod and a floating contact retained along the same axis as the second moving contact. Both contact systems are enclosed in a vacuum envelope. A mechanical adjustment system is provided for the floating contact, which allows it to be positioned so that the secondary moving contact and floating moving contact may engage at a set interval before the annular moving contact engages the annular stationary contact. A resistor or inductor is connected between the second contact system and a load to prevent a current in-rush into the load.

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 switching control device includes a unit to measure a power-supply-side voltage of a circuit breaker, a unit to calculate a current that flows through a resistor after a switch is turned on and before a circuit breaking unit is turned on, and to calculate an interelectrode voltage of the circuit breaking unit after the switch is turned on and before the circuit breaking unit is turned on, a unit to determine a target closing time point for the circuit breaking unit so that a target turn-on phase for the circuit breaking unit becomes a phase that is set in accordance with the capacitor, and to output a control signal such that the circuit breaking unit is closed at the target closing time point.

Disclosed herein is a circuit breaker having a closing resistor, which is capable of preventing impact caused when the circuit breaker is opened and closed from being transferred to peripheral structures. The circuit breaker having a closing resistor includes a fixed part having a fixed contact, a movable part having a movable contact, a closing resistor unit connected to the fixed part and having a closing resistor unit contact, a closing resistor movable part connected to the movable part and having a closing resistor movable contact, and a support structure slidably coupled to the closing resistor unit in a direction parallel to a movement direction of the closing resistor movable part, thereby enabling impact and vibration applied to the closing resistor unit to be absorbed by the support structure.

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.