A knife switch device for use in a switchgear or a ring main unit, the knife switch device including a stationary contact member, and a movable contact member, the movable contact member being rotatable about a main revolute joint for selectively opening and closing the knife switch device, the movable contact member including at least a first segment and a second segment, the first segment and the second segment being coupled by an auxiliary revolute joint, wherein the main revolute joint is arranged on the second segment, and wherein a rotation axis of the main revolute joint is substantially parallel to a rotation axis of the auxiliary revolute joint.

The electromagnetic relay comprises an auxiliary fixed terminal that has a configuration different from that of a fixed terminal and includes an auxiliary external input/output terminal and an auxiliary external output/input terminal that can be electrically connected to the auxiliary external input/output terminal. The electromagnetic relay comprises an auxiliary movable terminal that has a configuration different from that of a movable terminal and can electrically connect the auxiliary external input/output terminal and the auxiliary external output/input terminal.

A switch includes a first arm that is rotatably supported, a first contact member that is provided at a free end of the first arm, a second arm that is rotatably supported, and a second contact member that is provided at a free end of the second arm and is to come into contact with the first contact member. After the first contact member and the second contact member have come into contact with each other, a point of contact between the first contact member and the second contact member is displaced with rotational motions of the first arm and the second arm.

An electromagnetic relay includes plural pairs of fixed terminals each including an external input/output terminal and an external output/input terminal that can be electrically connected to the external input/output terminal the external input/output terminal and the external output/input terminal being paired with and separated from each other. A tip portion of the external input/output terminal and a tip portion of the external output/input terminal paired with each other are aligned along a straight line extending in a direction substantially parallel to a virtual straight line in a plan view, and the straight lines on which the respective pairs of the tip portions are aligned are offset from each other in a direction vertical to the virtual straight lines.

A method for separating welded contacts in a magnetically actuated switch assembly that includes providing multiple actuator hammer blows to the contacts. The method includes causing the contacts to close using, for example, a manual actuation device and detecting a high current condition that occurs when the contacts are closed. The method further includes electrically actuating the actuator to open the contacts in response to detecting the high current condition and determining that the contacts have not opened in response to the actuator being actuated because they are welded together. The method also includes electrically actuating the actuator to close the contacts when it is determined that they are welded together and again electrically actuating the actuator to open the contacts.

A switch-operation-determining device provided with a determination circuit for determining whether a switch has been operated, wherein the determination circuit is provided with: a first resistor, a first diode, and a second diode serially connected in the stated order from the power-source side, such that current flows from the power source toward a ground; and a control unit for comparing the anode potential of the first diode and a threshold potential, and determining that the switch has been operated when the anode potential of the first diode is lower. Of the first diode and the second diode, it is the second diode that is connected in parallel with the switch.

A protected switch includes first and second electromechanical relays with guided contacts, each including an electromagnet and electrical contacts. A first contact of the first relay and a first contact of the second relay are connected in series in order to form a switching circuit. The switch further includes an interconnection circuit which connects at least a portion of the other electrical contacts of the first and second relays. The excitation of the first electromagnet is conditional on the state of the second relay and the excitation of the second electromagnet is conditional on the state of the first relay.

Provided is a drive structure for a high-voltage direct-current relay, the drive structure comprising: a retaining frame, a stopper piece, a movable spring piece, and an elastic member. The retaining frame comprises two retaining side arms, a support plate, and a drive rod. The two retaining side arms are disposed at two sides of the support plate, and the drive rod is connected to a bottom portion of the support plate. The stopper piece has one end connected to a terminal end of one of the retaining side arms, and the other end connected to a terminal end of the other retaining side arm. The elastic member has one end pressing against the support plate and the other end pressing against the movable spring piece, the movable spring piece presses against the stopper piece, and the stopper piece is provided with an arc isolation portion. The drive structure for a high-voltage direct-current relay has an bottom-up assembly manner, in which the elastic member, the movable spring piece, and the stopper piece are stacked sequentially, and the stopper piece is connected to and retained by the two retaining side arms, thereby realizing a simple and fast assembly process, and increasing assembly efficiency of high-voltage direct-current relays. In addition, the arc isolation portion has an effect of isolating arcs, thereby improving a service life of high-voltage direct-current relays despite reverse arcs.

A relay state determination device includes a voltage value acquisition unit, a contact bounce time acquisition unit, and a state determination unit. The voltage value acquisition unit acquires a voltage value between one pair of contacts mutually opened and closed in a relay. The contact bounce time acquisition unit obtains a contact bounce time indicated by the one pair of contacts based on the temporal change in the voltage value after the ON instruction to the relay. The state determination unit compares the contact bounce time with a time threshold value to determine whether or not the relay 4 has deteriorated.

A protected switch includes first and second electromechanical relays with guided contacts, each including an electromagnet and electrical contacts. A first contact of the first relay and a first contact of the second relay are connected in series in order to form a switching circuit. The switch further includes an interconnection circuit which connects at least a portion of the other electrical contacts of the first and second relays. The excitation of the first electromagnet is conditional on the state of the second relay and the excitation of the second electromagnet is conditional on the state of the first relay.