# US 2017/0288388 A1 · Dc circuit breaker > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0288388 A1 - Document ID: US20170288388A1 - Status: Published application - Kind: A1 - Application number: 15/513,858 - Filed: 2015-06-05 - Published: 2017-10-05 - Earliest claimed: 2014-09-26 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Katsuhiko HORINOUCHI; Motohiro SATO; Kazuki TAKAHASHI; Ryo KAMIMAE; Sho TOKOYODA - Web page: https://patentgrep.com/patent/US20170288388A1 ## CPC - H02H 3/087: for DC applications - H01H 9/54: Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere - H01H 33/59: Circuit arrangements not adapted to a particular application of the switch and not otherwise provided for, e.g. for ensuring operation of the switch at a predetermined point in the AC cycle - H01H 33/596: {for interrupting DC} - H01H 77/02: in which the excess current itself provides the energy for opening the contacts, and having a separate reset mechanism - H01H 33/6661: {Combination with other type of switch, e.g. for load break switches (H01H33/143, H01H33/6662 take precedence)} - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) ## Abstract A DC circuit breaker includes: a mechanical switch provided on an electrical path through which a direct current flows; and a semiconductor switch connected in parallel with the mechanical switch. The mechanical switch includes a gas disconnector and a vacuum circuit breaker connected in series. Normally, the direct current flows through the mechanical switch. When interrupting the direct current, the vacuum circuit breaker is made nonconductive to allow the direct current to be commutated to the semiconductor switch, and subsequently the gas disconnector and the semiconductor switch are made nonconductive. A vacuum circuit breaker having a low withstand voltage can be used. ## Claims ### Claim 1 A DC circuit breaker comprising: a mechanical switch provided on an electrical path through which a direct current flows; and a semiconductor switch connected in parallel with the mechanical switch, the mechanical switch including a disconnector and a circuit breaker connected in series, normally, the direct current flowing through the mechanical switch, when interrupting the direct current, circuit breaker being made nonconductive to allow the direct current to be commutated to the semiconductor switch, subsequently contacts of the disconnector being disconnected from each other, and subsequently the semiconductor switch being made nonconductive. ### Claim 2 (canceled) ### Claim 3 (depends on 1) The DC circuit breaker according to claim 1, wherein contacts of the circuit breaker are disconnected from each other and subsequently the contacts of the disconnector are disconnected from each other. ### Claim 4 (depends on 3) The DC circuit breaker according to claim 3, wherein opening operation of the circuit breaker is started and subsequently opening operation of the disconnector is started. ### Claim 5 (depends on 3) The DC circuit breaker according to claim 3, wherein opening operation of the circuit breaker and opening operation of the disconnector are started simultaneously. ### Claim 6 (depends on 1) The DC circuit breaker according to claim 1, wherein an inter-electrode withstand voltage of the circuit breaker is higher than an inter-electrode voltage of the semiconductor switch in conducting state, not higher than an inter-electrode voltage (system voltage) of the semiconductor switch in non-conducting state, and lower than an inter-electrode withstand voltage of the disconnector. ### Claim 7 (depends on 1) The DC circuit breaker according to claim 1, further comprising a forced commutating circuit configured to force a current in an opposite direction to a direction of the direct current to flow to the circuit breaker when interrupting the direct current. ### Claim 8 (depends on 7) The DC circuit breaker according to claim 7, wherein the forced commutating circuit includes: a resonance circuit including a capacitor and a reactor connected in series; a charger configured to charge the capacitor in charging operation; and a switch configured to connect, in interrupting operation for interrupting the circuit breaker, the resonance circuit to the circuit breaker to allow the current in the opposite direction to the direction of the direct current to flow from the capacitor to the circuit breaker through the reactor. ### Claim 9 (depends on 7) The DC circuit breaker according to claim 7, wherein the forced commutating circuit includes: a battery; a resonance circuit including a capacitor and a reactor which are connected in series with the battery; and a switch configured to connect, in interrupting operation for interrupting the circuit breaker, the battery and the resonance circuit to the circuit breaker to allow the current in the opposite direction to the direction of the direct current to flow from the battery to the circuit breaker through the capacitor and the reactor. ### Claim 10 (depends on 7) The DC circuit breaker according to claim 7, wherein the forced commutating circuit further includes a resistance element configured to attenuate the current in the opposite direction to the direction of the direct current after the circuit breaker is made nonconductive. ### Claim 11 (depends on 7) The DC circuit breaker according to claim 7, further comprising a saturable reactor provided on the electrical path and connected in series with the circuit breaker, wherein the forced commutating circuit is configured to force the current in the opposite direction to the direction of the direct current to flow to the circuit breaker through the saturable reactor when interrupting the direct current. ### Claim 12 (depends on 1) The DC circuit breaker according to claim 1, wherein the circuit breaker is made nonconductive and subsequently the current in the opposite direction to the direction of the direct current is interrupted by the disconnector. ### Claim 13 (depends on 1) The DC circuit breaker according to claim 1, wherein the semiconductor switch includes a transistor. ### Claim 14 (depends on 13) The DC circuit breaker according to claim 13, wherein the semiconductor switch includes a plurality of the transistors connected in series. ### Claim 15 (depends on 13) The DC circuit breaker according to claim 13, wherein the semiconductor switch further includes a diode connected in antiparallel with the transistor. ### Claim 16 (depends on 1) The DC circuit breaker according to claim 1, further comprising a lighting arrester connected in parallel with the semiconductor switch and configured to absorb electrical energy after the semiconductor switch is made nonconductive. ### Claim 17 A DC circuit breaker comprising: a mechanical switch provided on an electrical path through which a direct current flows; and a semiconductor switch connected in parallel with the mechanical switch, the mechanical switch including a disconnector and a circuit breaker connected in series, normally, the direct current flowing through the mechanical switch, when interrupting the direct current, opening operation of the circuit breaker and opening operation of the disconnector being started simultaneously, the circuit breaker being made nonconductive to allow the direct current to be commutated to the semiconductor switch, and subsequently the disconnector and the semiconductor switch being made nonconductive. ### Claim 18 (depends on 17) The DC circuit breaker according to claim 17, wherein contacts of the circuit breaker are disconnected from each other and subsequently contacts of the disconnector are disconnected from each other.