JP4282310B2

JP4282310B2 - DC circuit breaker

Info

Publication number: JP4282310B2
Application number: JP2002334563A
Authority: JP
Inventors: 順松崎; 冨夫郷; 秋久片岡; 三孝本間; 芳充丹羽
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2002-11-19
Filing date: 2002-11-19
Publication date: 2009-06-17
Anticipated expiration: 2022-11-19
Also published as: JP2004171849A

Description

【０００１】
【発明の属する技術分野】
本発明は、真空遮断器で直流回路を遮断するにあたり、主遮断器と直列に接続された副遮断器の動作を改良した直流遮断器に関する。
【０００２】
【従来の技術】
従来の直流遮断器は、直流回路に主遮断器と副遮断器を直列接続し、主遮断器に並列接続された転流回路から転流電流を注入して電流零点を作り主遮断器で遮断を行い、副遮断器で直流回路を開路する構成となっている（例えば、特許文献１参照。）。
【０００３】
この直流遮断器は、図４に示すように、直流回路のＰ−Ｎ間には、接離自在の一対の電極を有する主遮断器１および副遮断器２が直列に接続されている。主遮断器１には、コンデンサ３と転流スイッチ４を直列接続した転流回路５が並列に接続され、また、エネルギー吸収のためのサージアブソーバ６が同様に並列に接続されている。そして、主遮断器１および副遮断器２は、同一の操作機構７でほぼ同時に開閉されるようになっている。
【０００４】
このような回路構成において、図５に示すように、直流回路に過大な事故電流Ｉａが流れる場合を考えると、主遮断器１に制御回路から遮断指令が発せられ、主遮断器１の一方の電極から他方の電極が開離し、両電極間に事故電流Ｉａが流れる。この事故電流Ｉａは、両電極間が開極動作位置となる時間ｔ１に達すると、予め充電しているコンデンサ３と転流スイッチ４が動作して逆方向転流電流が重畳され、実線で示したように交流波形となり電流零点となる時間ｔ２で遮断される。このｔ１からｔ２までの時間は、前記コンデンサ３の容量によって決まるものであり、例えばコンデンサとして１５００μＦの容量のものを用いると約０．１５ｍｓとなる。
【０００５】
また、主遮断器１と同時に副遮断器２も動作を開始して電極間が開離し、この副遮断器２の両電極間にも同様の事故電流Ｉａが流れる。この事故電流Ｉａは、点線で示したように主遮断器１が遮断完了する時間ｔ２まで上昇を続け、その後、転流回路５のコンデンサ３の容量と直流回路の負荷抵抗の時定数で減衰して、電流零点になる時間ｔ３で遮断される。この時間ｔ２からｔ３までは、負荷抵抗に左右されるが、一般的には数ｍｓから数１００ｍｓの範囲となる。
【０００６】
このように主遮断器１および副遮断器２は、同一の操作機構７で操作されてほぼ同時に開極を始め、主遮断器１で事故電流Ｉａを遮断した後、副遮断器２で直流回路が開路されるようになっている。
【０００７】
【特許文献１】
特開平５−２３４４７１号公報（第２頁、図1）
【０００８】
【発明が解決しようとする課題】
上記の従来の直流遮断器においては、以下のような問題がある。
【０００９】
主遮断器１および副遮断器２がほぼ同時に開極を始めるため、副遮断器２の電極間には、主遮断器１の電極間より長く事故電流Ｉａが流れ続けることになる。即ち、副遮断器２の電極間には、図５に示す斜線領域Ａのアークエネルギーが主遮断器１より余計に加わり、電極の消耗量が大きくなり、その結果、電極を太径にするなど副遮断器２を大容量としなくてはならなかった。また、消耗が進めば、直流回路を開路できなくなる恐れがあった。
【００１０】
従って、本発明は、副遮断器が開極を始める時間を制御し、電極の消耗量を抑制するようにした直流遮断器を得ることを目的とする。
【００１１】
【課題を解決するための手段】
上記の目的を達成するために、第１の発明の直流遮断器は、直流回路に直列接続された主遮断器および副遮断器と、前記主遮断器に並列接続されたコンデンサと転流スイッチを有する前記直流回路に逆方向転流電流を重畳する転流回路と、前記直流回路の負荷側に設けられた変流器とを備え、前記主遮断器が開極を始めて前記転流回路から転流電流が注入され、前記主遮断器の電極間で直流電流を遮断し、この直流電流が前記直流回路の抵抗で減衰し、前記変流器で電流零点を検出したとき、前記副遮断器を開極させるようにしたことを特徴とする。
【００１２】
このような構成によれば、副遮断器の電極間に流れるアークエネルギーが抑制され、電極の消耗量を極めて少なくすることができる。
【００１３】
また、第２の発明の直流遮断器は、直流回路に直列接続された主遮断器および副遮断器と、前記主遮断器に並列接続されたコンデンサと転流スイッチを有する前記直流回路に逆方向転流電流を重畳する転流回路と、前記主遮断器の主回路導体に設けられた変流器とを備え、前記主遮断器が開極を始めて前記転流回路から転流電流が注入され、前記主遮断器の電極間と前記転流回路とで形成される閉回路で直流電流が電流零点を作ったとき、この電流零点を前記変流器で検出し、前記副遮断器を開極させるようにしたことを特徴とする。
【００１４】
このような構成によれば、副遮断器の電極間に流れるアークエネルギーが抑制され、電極の消耗量を少なくすることができる。
【００１５】
【発明の実施の形態】
（第１の実施の形態）
先ず、本発明の第１の実施の形態に係る直流遮断器を図１および図２を参照して説明する。図１は、本発明の第１の実施の形態に係る直流遮断器の回路構成図、図２は、本発明の第１の実施の形態に係る直流遮断器の動作を説明するための説明図である。なお、各図において、従来と同様の構成部分については、同一符号を付した。
【００１６】
図１に示すように、直流回路のＰ−Ｎ間には、例えば真空バルブからなる接離自在の一対の電極を有する主遮断器１および副遮断器２が直列に接続されている。この主遮断器１には、コンデンサ３と転流スイッチ４を直列接続した転流回路５が並列に接続され、また、エネルギー吸収のためのサージアブソーバ６が同様に並列に接続されている。これらが接続された直流回路の負荷側には、電流を検出するための変流器１０が設けられている。そして、主遮断器１および副遮断器２には、夫々操作機構１１、１２が設けられそれぞれ個別に開閉制御されるようになっている。
【００１７】
このような回路構成において、図２に示すように、直流回路に過大な事故電流Ｉａが流れた場合、変流器１０と接続された図示しない制御回路から主遮断器１に遮断指令が発せられ、操作機構１１が動作して主遮断器１における一方の電極から他方の電極が開離し、両電極間に事故電流Ｉａが流れる。この事故電流Ｉａは、両電極間が開極動作位置となる時間ｔ１に達すると、予め充電しているコンデンサ３と転流スイッチ４が動作して逆方向転流電流が重畳され、実線で示したように交流波形となり電流零点となる時間ｔ２で遮断される。
【００１８】
このｔ１からｔ２までの時間は、従来と同様に、コンデンサ３の容量によって決まるものであり、例えばコンデンサの容量に１５００μＦを用いると約０．１５ｍｓとなる。
【００１９】
一方、副遮断器２は、事故電流Ｉａが主遮断器１の電極間で遮断完了した後の、直流回路の負荷側に設けられた変流器１０が、この直流回路の電流零点を検出した時間ｔ３のとき、制御回路から開路指令が発せられ、操作機構１２が動作して開極するようになっている。即ち、転流回路５のコンデンサ３の容量と直流回路の負荷側などに接続された抵抗値との時定数で減衰して電流零点になるｔ３において、副遮断器２を開極し、直流回路の開路を確実なものとさせている。
【００２０】
なお、電流零点の検出において、測定誤差などから零点近傍の微小電流を副遮断器２で遮断してもアークエネルギーは極めて小さく、確実に開路することができる。また、ｔ２からｔ３までの時間は、従来と同様に、一般的に数ｍｓから数１００ｍｓの範囲である。このような制御は、静止形リレーを用いた制御回路により、電流零点の検出や開路指令の信号制御が行われるので、大きな時間の遅れがないようにできる。
【００２１】
上記第１の実施の形態の直流遮断器によれば、事故電流を主遮断器１で遮断後、直流回路を開路させる副遮断器２をコンデンサ３の容量と直流回路の抵抗値との関係で減衰して電流零点を向かえたときに開極させているので、副遮断器２の電極間に発生するアークエネルギーは、電流零点近傍での微小電流によるものとなり極めて抑制される。
【００２２】
このため、副遮断器２の電極の消耗が極めて少なくなり確実に直流回路を開路でき、また、電極を細径の小容量とすることができる。
【００２３】
（第２の実施の形態）
次に、本発明の第２の実施の形態に係る直流遮断器を図３を参照して説明する。図３は、本発明の第２の実施の形態に係る直流遮断器の回路構成図である。
【００２４】
図３に示すように、直流遮断器の回路構成は、第１の実施の形態と同様に、主遮断器１、副遮断器２、転流回路５、サージアブソーバ６および操作機構１１、１２から構成されている。しかし、異なる点は、電流を検出するための変流器１３が主遮断器１の主回路導体に設けられていることである。
【００２５】
このような回路構成において、再び図２を参照して説明する。図２に示すように、直流回路に過大な事故電流Ｉａが流れた場合、変流器１３と接続された図示しない制御回路から主遮断器１に遮断指令が発せられ、操作機構１１が動作して第１の実施の形態と同様に逆方向転流電流が重畳され、実線で示したように交流波形となり電流零点となる時間ｔ２で遮断される。
【００２６】
このｔ１からｔ２までの時間は、第１の実施の形態と同様に、例えばコンデンサの容量に１５００μＦを用いると約０．１５ｍｓとなる。
【００２７】
一方、副遮断器２は、主遮断器１と転流回路５との閉回路で作られる事故電流Ｉａに逆方向転流電流が重畳されて電流零点となる時間ｔ２になったとき、この電流零点を変流器１３で検出して制御回路から開路指令が発せられ、操作機構１２が動作して開極するようになっている。そして、この副遮断器２は、電極間でアークを継続しながらコンデンサ３の容量と直流回路の抵抗の時定数で減衰して電流零点になる時間ｔ３において、遮断完了して直流回路の開路を確実なものとさせている。
【００２８】
これにより、副遮断器２の電極間には、時間ｔ２からｔ３までのアークエネルギーが加わることになるが、従来の時間ｔ１からｔ３までと比べて抑制されることになる。また、このような制御は、静止形リレーを用いた制御回路により、電流零点の検出や開路指令の信号制御が行われるので、大きな時間の遅れがないようにできる。
【００２９】
上記第２の実施の形態の直流遮断器によれば、事故電流を主遮断器１と転流回路５で作る電流零点において副遮断器２を開極させているので、副遮断器２の電極間に発生するアークエネルギーが抑制される。このため、副遮断器２の電極の消耗量が少なく確実に直流回路を開路でき、また、電極を細径の小容量とすることができる。
【００３０】
【発明の効果】
以上述べたように、本発明によれば、主遮断器が開極して事故電流に転流回路からの逆方向転流電流を重畳して電流零点を作ったとき、または、その後事故電流が直流回路の抵抗値により減衰して電流零点となったときに副遮断器を開極させ直流回路を開路させているので、副遮断器の電極間に流れるアークエネルギーが抑制され電極の消耗量が少なくなり、その結果、副遮断器の電極を小容量とすることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係る直流遮断器の回路構成図。
【図２】本発明の第１および第２の実施の形態に係る直流遮断器の動作を説明するための説明図。
【図３】本発明の第２の実施の形態に係る直流遮断器の回路構成図。
【図４】従来の直流遮断器の回路構成図。
【図５】従来の直流遮断器の動作を説明するための説明図。
【符号の説明】
１主遮断器
２副遮断器
３コンデンサ
４転流スイッチ
５転流回路
６サージアブソーバ
７、１１、１２操作機構
１０、１３変流器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a DC circuit breaker in which the operation of a sub circuit breaker connected in series with a main circuit breaker is improved when a DC circuit is cut off by a vacuum circuit breaker.
[0002]
[Prior art]
A conventional DC circuit breaker has a main circuit breaker and a sub circuit breaker connected in series to a DC circuit, and a commutation current is injected from a commutation circuit connected in parallel to the main circuit breaker to create a current zero point and cut off by the main circuit breaker. And the DC circuit is opened by the auxiliary circuit breaker (see, for example, Patent Document 1).
[0003]
In this DC circuit breaker, as shown in FIG. 4, a main circuit breaker 1 and a sub circuit breaker 2 having a pair of electrodes that are detachable are connected in series between PN of the DC circuit. A commutation circuit 5 in which a capacitor 3 and a commutation switch 4 are connected in series is connected in parallel to the main circuit breaker 1, and a surge absorber 6 for energy absorption is similarly connected in parallel. The main circuit breaker 1 and the sub circuit breaker 2 are opened and closed almost simultaneously by the same operation mechanism 7.
[0004]
In such a circuit configuration, as shown in FIG. 5, considering a case where an excessive fault current Ia flows in the DC circuit, a cutoff command is issued from the control circuit to the main circuit breaker 1, and one of the main circuit breakers 1 is The other electrode is separated from the electrode, and an accident current Ia flows between the two electrodes. When the accident current Ia reaches the time t1 when the opening between both electrodes reaches the opening operation position, the capacitor 3 and the commutation switch 4 that are charged in advance operate to superimpose the reverse commutation current, and are indicated by a solid line. As shown, the AC waveform is cut off at time t2 when the current becomes zero. The time from t1 to t2 is determined by the capacity of the capacitor 3. For example, when a capacitor having a capacity of 1500 μF is used, the time is about 0.15 ms.
[0005]
In addition, the secondary circuit breaker 2 starts operating simultaneously with the main circuit breaker 1 and the electrodes are separated, and a similar fault current Ia flows between both electrodes of the secondary circuit breaker 2. This fault current Ia continues to rise until the time t2 when the main circuit breaker 1 completes breaking, as indicated by the dotted line, and then decays with the time constant of the capacitance of the capacitor 3 of the commutation circuit 5 and the load resistance of the DC circuit. Thus, it is interrupted at time t3 when the current becomes zero. This time t2 to t3 depends on the load resistance, but generally ranges from several ms to several hundred ms.
[0006]
As described above, the main circuit breaker 1 and the sub circuit breaker 2 are operated by the same operation mechanism 7 and start opening at almost the same time. After the main circuit breaker 1 interrupts the accident current Ia, the sub circuit breaker 2 operates the DC circuit. Is now open.
[0007]
[Patent Document 1]
JP-A-5-234471 (second page, FIG. 1)
[0008]
[Problems to be solved by the invention]
The above-mentioned conventional DC circuit breaker has the following problems.
[0009]
Since the main circuit breaker 1 and the sub circuit breaker 2 start to open almost simultaneously, the accident current Ia continues to flow between the electrodes of the sub circuit breaker 2 for a longer time than between the electrodes of the main circuit breaker 1. That is, between the electrodes of the secondary circuit breaker 2, arc energy in the hatched area A shown in FIG. 5 is applied more than the main circuit breaker 1, and the amount of consumption of the electrodes increases, resulting in the electrodes having a large diameter. The auxiliary circuit breaker 2 had to have a large capacity. Further, if the consumption progresses, the DC circuit may not be opened.
[0010]
Therefore, an object of the present invention is to obtain a DC circuit breaker which controls the time when the auxiliary circuit breaker starts opening and suppresses the amount of electrode consumption.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a DC circuit breaker according to a first invention comprises a main circuit breaker and a sub circuit breaker connected in series to a DC circuit, a capacitor and a commutation switch connected in parallel to the main circuit breaker. A commutation circuit for superimposing a reverse commutation current on the DC circuit, and a current transformer provided on the load side of the DC circuit, and the main circuit breaker starts to open and commutates from the commutation circuit. When a current is injected, the direct current is cut off between the electrodes of the main circuit breaker, the direct current is attenuated by the resistance of the direct current circuit, and when the current zero point is detected by the current transformer, the sub circuit breaker is It is characterized in that it is opened.
[0012]
According to such a configuration, arc energy flowing between the electrodes of the sub-breaker is suppressed, and the amount of consumption of the electrodes can be extremely reduced.
[0013]
The DC circuit breaker of the second invention is reverse to the DC circuit having a main circuit breaker and a sub circuit breaker connected in series to the DC circuit, a capacitor connected in parallel to the main circuit breaker, and a commutation switch. A commutation circuit for superimposing a commutation current; and a current transformer provided on a main circuit conductor of the main circuit breaker, and the commutation current is injected from the commutation circuit when the main circuit breaker starts to open. When a DC current forms a current zero point in a closed circuit formed between the electrodes of the main circuit breaker and the commutation circuit , the current zero point is detected by the current transformer and the sub circuit breaker is opened. It was made to let it be made to do.
[0014]
According to such a configuration, arc energy flowing between the electrodes of the auxiliary circuit breaker is suppressed, and the amount of consumption of the electrodes can be reduced.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
First, a DC circuit breaker according to a first embodiment of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a circuit configuration diagram of a DC circuit breaker according to the first embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining the operation of the DC circuit breaker according to the first embodiment of the present invention. It is. In addition, in each figure, the same code | symbol was attached | subjected about the component similar to the past.
[0016]
As shown in FIG. 1, the main circuit breaker 1 and the sub circuit breaker 2 which have a pair of electrodes which can be contacted / separated which consist of a vacuum valve, for example are connected in series between PN of a DC circuit. A commutation circuit 5 in which a capacitor 3 and a commutation switch 4 are connected in series is connected in parallel to the main circuit breaker 1, and a surge absorber 6 for energy absorption is connected in parallel as well. A current transformer 10 for detecting current is provided on the load side of the DC circuit to which these are connected. The main circuit breaker 1 and the sub circuit breaker 2 are provided with operation mechanisms 11 and 12, respectively, and are individually controlled to be opened and closed.
[0017]
In such a circuit configuration, as shown in FIG. 2, when an excessive fault current Ia flows in the DC circuit, a shut-off command is issued to the main circuit breaker 1 from a control circuit (not shown) connected to the current transformer 10. Then, the operation mechanism 11 is operated, the other electrode is separated from one electrode in the main circuit breaker 1, and the fault current Ia flows between both electrodes. When the accident current Ia reaches the time t1 when the opening between both electrodes reaches the opening operation position, the capacitor 3 and the commutation switch 4 that are charged in advance operate to superimpose the reverse commutation current, and are indicated by a solid line. As shown, the AC waveform is cut off at time t2 when the current becomes zero.
[0018]
The time from t1 to t2 is determined by the capacity of the capacitor 3 as in the conventional case. For example, when 1500 μF is used for the capacity of the capacitor, the time is about 0.15 ms.
[0019]
On the other hand, in the secondary circuit breaker 2, the current transformer 10 provided on the load side of the DC circuit after the fault current Ia is completed between the electrodes of the main circuit breaker 1 has detected the current zero point of the DC circuit. At time t3, an opening command is issued from the control circuit, and the operating mechanism 12 operates to open the pole. That is, the secondary circuit breaker 2 is opened and the DC circuit is opened at t3 when the current is attenuated by the time constant between the capacitance of the capacitor 3 of the commutation circuit 5 and the resistance value connected to the load side of the DC circuit. The opening of the is made sure.
[0020]
In detecting the current zero point, even if a minute current near the zero point is interrupted by the secondary circuit breaker 2 due to a measurement error or the like, the arc energy is extremely small and the circuit can be opened reliably. Further, the time from t2 to t3 is generally in the range of several ms to several hundred ms as in the conventional case. Such control is performed by detecting a current zero point and opening control signal control by a control circuit using a static relay, so that there is no significant time delay.
[0021]
According to the DC circuit breaker of the first embodiment, the secondary circuit breaker 2 that opens the DC circuit after the fault current is interrupted by the main circuit breaker 1 is related to the capacitance of the capacitor 3 and the resistance value of the DC circuit. Since the electrode is opened when the current zero point is attenuated, the arc energy generated between the electrodes of the secondary circuit breaker 2 is caused by a minute current near the current zero point and is extremely suppressed.
[0022]
For this reason, the consumption of the electrode of the secondary circuit breaker 2 is extremely reduced, so that the DC circuit can be opened reliably, and the electrode can be made to have a small diameter and a small capacity.
[0023]
(Second Embodiment)
Next, a DC circuit breaker according to a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a circuit configuration diagram of a DC circuit breaker according to the second embodiment of the present invention.
[0024]
As shown in FIG. 3, the circuit configuration of the DC circuit breaker is similar to that of the first embodiment, from the main circuit breaker 1, the sub circuit breaker 2, the commutation circuit 5, the surge absorber 6, and the operation mechanisms 11 and 12. It is configured. However, the difference is that a current transformer 13 for detecting a current is provided in the main circuit conductor of the main circuit breaker 1.
[0025]
Such a circuit configuration will be described again with reference to FIG. As shown in FIG. 2, when an excessive fault current Ia flows through the DC circuit, a control circuit (not shown) connected to the current transformer 13 issues a disconnection command to the main circuit breaker 1, and the operation mechanism 11 operates. In the same manner as in the first embodiment, the reverse commutation current is superimposed, and as shown by the solid line, the alternating current waveform is obtained and is interrupted at time t2 when the current becomes zero.
[0026]
The time from t1 to t2 is about 0.15 ms when 1500 μF is used for the capacitor, for example, as in the first embodiment.
[0027]
On the other hand, the secondary circuit breaker 2 has this current t2 when the reverse commutation current is superimposed on the fault current Ia created by the closed circuit of the main circuit breaker 1 and the commutation circuit 5 and becomes the current zero point. The zero point is detected by the current transformer 13, an opening command is issued from the control circuit, and the operating mechanism 12 operates to open the pole. Then, the secondary circuit breaker 2 completes the circuit break and opens the DC circuit at time t3 when the arc continues between the electrodes and decays with the time constant of the capacity of the capacitor 3 and the resistance of the DC circuit to reach the current zero point. Make sure.
[0028]
As a result, arc energy from the time t2 to t3 is applied between the electrodes of the auxiliary circuit breaker 2, but is suppressed as compared with the conventional time t1 to t3. In addition, since such control performs detection of the current zero point and signal control of the open circuit command by a control circuit using a static relay, it is possible to prevent a large time delay.
[0029]
According to the DC circuit breaker of the second embodiment, the secondary circuit breaker 2 is opened at the current zero point at which the fault current is generated by the main circuit breaker 1 and the commutation circuit 5, so that the electrode of the secondary circuit breaker 2 Arc energy generated between them is suppressed. For this reason, the amount of consumption of the electrode of the secondary circuit breaker 2 is small, and the DC circuit can be opened reliably, and the electrode can be made to have a small diameter and a small capacity.
[0030]
【The invention's effect】
As described above, according to the present invention, when the main circuit breaker is opened and the reverse commutation current from the commutation circuit is superimposed on the accident current to create a current zero point, or the accident current is since then open the DC circuit to opening the auxiliary circuit breaker when a zero current is attenuated by the resistance value of the DC circuit, consumption of the secondary breaker is the electrode arc energy flowing between the suppression electrode As a result, the sub-breaker electrode can be reduced in capacity.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram of a DC circuit breaker according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram for explaining the operation of the DC circuit breakers according to the first and second embodiments of the present invention.
FIG. 3 is a circuit configuration diagram of a DC circuit breaker according to a second embodiment of the present invention.
FIG. 4 is a circuit configuration diagram of a conventional DC circuit breaker.
FIG. 5 is an explanatory diagram for explaining the operation of a conventional DC circuit breaker.
[Explanation of symbols]
1 Main circuit breaker 2 Sub circuit breaker 3 Capacitor 4 Commutation switch 5 Commutation circuit 6 Surge absorber 7, 11, 12 Operating mechanism 10, 13 Current transformer

Claims

A main circuit breaker and a sub circuit breaker connected in series to a DC circuit;
A commutation circuit for superimposing a reverse commutation current on the DC circuit having a capacitor and a commutation switch connected in parallel to the main circuit breaker ;
A current transformer provided on the load side of the DC circuit ,
When the main circuit breaker starts to open, a commutation current is injected from the commutation circuit, a direct current is interrupted between the electrodes of the main circuit breaker, and the direct current is attenuated by a resistance of the direct current circuit, and the variable current is interrupted. A DC circuit breaker characterized by opening the auxiliary circuit breaker when a current zero point is detected by a flow circuit.

A main circuit breaker and a sub circuit breaker connected in series to a DC circuit;
A commutation circuit for superimposing a reverse commutation current on the DC circuit having a capacitor and a commutation switch connected in parallel to the main circuit breaker ;
A current transformer provided on the main circuit conductor of the main circuit breaker ,
The main circuit breaker is injected commutation current from the commutation circuit started opening, when the main circuit breaker of the closed circuit direct current and the electrodes are formed by said commutation circuit is made the current zero point The direct current circuit breaker is characterized in that the current zero point is detected by the current transformer and the auxiliary circuit breaker is opened.