Abstract: A fluid level measurement system using a buoyant body includes a guide part installed in a direction perpendicular to the bottom surface of a fluid storage tank, and provided with a space in which a fluid can move therein; a buoyant body inserted into the guide part, and configured to float along the surface of the fluid inside the guide part; and a measurement part coupled to the top end of the guide part, and configured to measure the level of the surface of the fluid inside the fluid storage tank by transmitting a signal toward the buoyant body in the inner space of the guide part and then receiving a signal reflected from the buoyant body.

Abstract: The present invention relates to a circuit breaker operating current/fault current measuring device using a single Rogowski coil has an advantage of reducing an installation space and a manufacturing cost by simultaneously measuring an operating current and a fault current with the single Rogowski coil and has an advantage of improving reliability by simultaneously satisfying accuracy required for measurement of the operating current and the fault current. The circuit breaker operating current/fault current measuring device using a single Rogowski coil according to the present invention is configured with a Rogowski coil installed to wrap around a current-carrying conductor, a protection circuit outputting a fault voltage based on a voltage generated from a tap installed on a portion of the Rogowski coil, and a measurement circuit outputting an operating voltage based on a voltage generated in the entire coil of the Rogowski coil.

Abstract: A connection structure of a plurality of switching modules that reduces required insulation voltage significantly when the plurality of switching modules is connected to each other in series is proposed. A switching module connection structure includes: n (n?1, integer) switching modules arranged in two or more columns and all connecting to each other in series from a first switching module in a first column to a last switching module in a last column; and insulating members disposed between at least some switching modules for each column.

Abstract: A connection structure of a plurality of switching modules that reduces required insulation voltage significantly when the plurality of switching modules is connected to each other in series is proposed. A switching module connection structure includes: n (n?1, integer) switching modules arranged in two or more columns and all connecting to each other in series from a first switching module in a first column to a last switching module in a last column; and insulating members disposed between at least some switching modules for each column.

Abstract: Provided is a DC circuit breaker capable of interrupting a failure current in both directions which flows in a DC transmission line when a failure occurs in the DC transmission line. The DC circuit breaker includes: a first mechanical switch connected to a first DC transmission line at a first side thereof, and connected to a first conductive connecting member at a second side thereof; a second mechanical switch connected to the first conductive connecting member at a first side thereof, and connected to a second DC transmission line at a second side thereof; a first diode connected to the first mechanical switch in parallel; a second diode serially connected to the first diode through the second conductive connecting member, and connected to the second mechanical switch 120 in parallel; and a semiconductor switching circuit switching a flow of a failure current when a failure occurs.

Abstract: Provided is a high voltage DC circuit breaker that interrupts a fault current flowing through a high voltage DC transmission line with a vacuum circuit breaker and a gas circuit breaker connected in series. The circuit breaker includes: a vacuum circuit breaker installed on a DC transmission line and operating to interrupt a current in the DC transmission line when a fault occurs on either side of the DC transmission line; a gas circuit breaker connected in series with the vacuum interrupter; an LC circuit connected in parallel with the vacuum circuit breaker and including a capacitor and a reactor connected in series to induce LC resonance; a first bidirectional switching device connected in series with the LC circuit and switching a current flowing in any of two opposite directions; and a second bidirectional switching device connected in parallel with the LC circuit.

Abstract: The present invention relates to a vacuum interrupter for a circuit breaker capable of forming and releasing a short circuit by moving two movable electrodes in forward/backward directions, and a driving method therefor. The vacuum interrupter according to the present invention includes: a housing with a vacuum state therein; and first and second movable electrodes partially accommodated within the housing, and attached to first and second movable contacts at respective ends thereof, wherein the first and second movable electrodes are capable of moving in forward/backward directions, and the first and second movable contacts contact each other and separate from each other by the movement in forward/backward directions of the first and second electrodes.

Abstract: An electromagnetic repulsion actuator for a circuit breaker is provided. The actuator can include a housing; a first fixed electrode having therein an operating space open at both sides; a pair of movable electrodes capable of reciprocally moving and being electrically connected to the first fixed electrode; second fixed electrodes selectively contacting the pair of movable electrodes to be electrically connected thereto, thereby transferring power supplied from a first side to a second side; and actuating coils selectively moving the movable electrodes in a direction of being separated from the second fixed electrodes by generating electromagnetic force from induced current. In the present invention as above, the structure of a circuit breaker is simplified and moving speeds of the movable electrodes are increased since the movable electrodes move by using induced current generated by a close coil and open coils to perform an open operation.

Abstract: The present invention relates to a vacuum interrupter for a circuit breaker capable of forming and releasing a short circuit by moving two movable electrodes in forward/backward directions, and a driving method therefor. The vacuum interrupter according to the present invention includes: a housing with a vacuum state therein; and first and second movable electrodes partially accommodated within the housing, and attached to first and second movable contacts at respective ends thereof, wherein the first and second movable electrodes are capable of moving in forward/backward directions, and the first and second movable contacts contact each other and separate from each other by the movement in forward/backward directions of the first and second electrodes.

Abstract: An electromagnetic repulsion actuator for a circuit breaker is provided. The actuator can include a housing; a first fixed electrode having therein an operating space open at both sides; a pair of movable electrodes capable of reciprocally moving and being electrically connected to the first fixed electrode; second fixed electrodes selectively contacting the pair of movable electrodes to be electrically connected thereto, thereby transferring power supplied from a first side to a second side; and actuating coils selectively moving the movable electrodes in a direction of being separated from the second fixed electrodes by generating electromagnetic force from induced current. In the present invention as above, the structure of a circuit breaker is simplified and moving speeds of the movable electrodes are increased since the movable electrodes move by using induced current generated by a close coil and open coils to perform an open operation.

Abstract: Provided is a high voltage DC circuit breaker that interrupts a fault current flowing through a high voltage DC transmission line with a vacuum circuit breaker and a gas circuit breaker connected in series. The circuit breaker includes: a vacuum circuit breaker installed on a DC transmission line and operating to interrupt a current in the DC transmission line when a fault occurs on either side of the DC transmission line; a gas circuit breaker connected in series with the vacuum interrupter; an LC circuit connected in parallel with the vacuum circuit breaker and including a capacitor and a reactor connected in series to induce LC resonance; a first bidirectional switching device connected in series with the LC circuit and switching a current flowing in any of two opposite directions; and a second bidirectional switching device connected in parallel with the LC circuit.

Abstract: The present invention relates to a bidirectional direct current (DC) circuit breaker for interrupting a fault current flowing through a DC line for power transmission or distribution in case a fault occurs at one side of the DC line.