JP2019071239A - Direct current cutout gear - Google Patents

Abstract

Kind Code: A1 In a direct current interrupting device, a power supply for a gate circuit of a semiconductor switching element is established regardless of the arc level of a mechanical circuit breaker without separately providing a power supply for the gate circuit. An auxiliary circuit (3) is connected in parallel to a first mechanical breaker (CB1). The AC current transformer CT has a primary side connected between the first system 1 and the second system 2 and a secondary side connected to the auxiliary circuit 3 . The auxiliary circuit 3 connects the first and second semiconductor switching elements T1 and T2 in anti-series between the first system 1 and the second system 2 . When the AC current transformer CT detects a short-circuit current, the output current on the secondary side of the AC current transformer is input to the gate terminals of the first and second semiconductor switching elements T1 and T2. First and second capacitors C1 and C2 are connected between the gate terminals and emitter terminals of the first and second semiconductor switching elements T1 and T2. First and second resistors R1 and R2 are connected to discharge electric charges charged in the first and second capacitors C1 and C2. [Selection drawing] Fig. 1

Description

  The present invention relates to a DC interrupting device capable of interrupting bidirectional DC current.

  Patent Document 1 discloses a hybrid circuit breaker including a mechanical circuit breaker and an auxiliary circuit having a semiconductor switching element connected in parallel to the mechanical circuit breaker as a circuit breaker for interrupting an electric path when a short circuit accident or the like occurs in a system. , 2).

  Patent Document 1 shows an example of an AC shutoff device, and Patent Documents 2 and 3 show an example of a DC shutoff device. Unlike the alternating current, the direct current does not have a zero point, so there is a problem that the arc generated when the machine breaker is opened can not be extinguished. In Patent Document 2, a zero point is created by diverting the current at the time of opening the mechanical circuit breaker to the auxiliary circuit composed of the semiconductor switching element, and the arc is extinguished.

  The semiconductor switching element is turned on and off by the gate signal. Usually, a power supply for a gate drive circuit that generates a gate signal is separately provided by a switching power supply device or the like. On the other hand, in patent documents 1 and 2 etc., it is considered as circuit composition which does not provide a gate drive power supply of an individual semiconductor switching element, and miniaturization of a hybrid circuit breaker is attained.

  The cutoff devices of Patent Documents 1 and 2 are characterized in that the power supply for driving the gate of the semiconductor switching element is unnecessary, and the Patent Document 3 is characterized in that the power supply for mechanical circuit breaker is unnecessary.

Unexamined-Japanese-Patent No. 09-274833 gazette JP, 2015-50080, A Unexamined-Japanese-Patent No. 2010-103048

  The circuit breaker of Patent Document 1 is a hybrid circuit breaker in which a mechanical circuit breaker and a semiconductor switching element (thyristor) are used in combination. The gate power of the thyristor is supplied using an alternating current transformer. The hybrid circuit breaker diverts the passing current of the mechanical circuit breaker to the thyristor at the time of interruption. However, patent document 1 presupposes the application to an alternating current system.

  In the direct current system, no zero point is generated in the current. Therefore, once the thyristor is turned on to flow the direct current, there is no means for turning off the thyristor, and the current can not be cut off. Therefore, the interruption | blocking apparatus of patent document 1 can not be applied to a direct current | flow interruption apparatus. Moreover, in patent document 1, it is necessary to input the signal for operating a thyristor from the outside, and the control apparatus for it is needed.

  Patent Document 2 is a hybrid circuit breaker corresponding to a DC system. An arc voltage generated when the mechanical circuit breaker is opened is applied to and driven by the gate terminal of the semiconductor switching element.

  When an IGBT is used as the semiconductor switching element, generally, a voltage of about 15 V is applied to the gate terminal when turning on. Therefore, it is necessary to select a mechanical circuit breaker having an arc voltage of 15 V or more.

  In addition, if the contact wear of the mechanical circuit breaker is advanced by the arc, the arc voltage may be changed. For example, in an air circuit breaker, the arc voltage decreases as the current increases. Therefore, the IGBT can not be turned on with a large current, and there is a possibility that the cutoff may fail.

  Conversely, in the vacuum circuit breaker, the arc voltage increases as the current increases. In one example, the arc voltage is 15 V at a current of 4 kA, and there is a possibility that the IGBT can not be turned on at a cut-off short-circuit current lower than that.

  When using a vacuum circuit breaker, when current starts to commutate to the semiconductor switching element, the arc voltage may decrease and the semiconductor switching element may start to be turned off. If the OFF speed of the semiconductor switching device is high, the current commutated to the semiconductor switching device may be returned to the mechanical circuit breaker, resulting in a failure to shut off.

  If the OFF speed of the semiconductor switching element is reduced, the risk of failure to shut off can be reduced, but it takes time to shut off and during that time the short circuit current increases. As a result, the conduction loss and the turn-off loss of the semiconductor switching element increase, and the possibility that the semiconductor switching element is destroyed by heat increases.

  In the configuration of Patent Document 3, an alternating current transformer is used to supply power to the control circuit of the machine breaker. However, the circuit of Patent Document 3 is not a hybrid circuit breaker. Therefore, there is a problem that the arc that can not be extinguished at the time of opening can not be used, and the life of the mechanical circuit breaker is reduced due to the arc.

  As described above, in the direct current shutoff device, it becomes an issue to establish the power supply of the gate circuit regardless of the arc level of the mechanical circuit breaker without separately providing the power supply for the gate circuit of the semiconductor switching element. .

  The present invention has been made in view of the above conventional problems, and one aspect thereof is a first mechanical circuit breaker connected between a first system and a second system, and the first mechanical circuit breaker When the auxiliary circuit connected in parallel with respect to the primary side is connected between the first system and the second system, the secondary side is connected to the auxiliary circuit, and the primary side detects a short circuit current And an alternating current transformer for outputting current to the auxiliary circuit on the secondary side, wherein the auxiliary circuit is connected in reverse series between the first system and the second system, and the alternating current transformer is a short circuit current. Connected between the gate terminal and the emitter terminal of the first semiconductor switching element, and the first and second semiconductor switching elements which input the output current on the secondary side of the alternating current transformer to the gate terminal when detecting A first capacitor and a gate of the second semiconductor switching element A second capacitor connected between the child and the emitter terminal, the first, characterized in that a resistor for discharging charges charged in the second capacitor, comprising a.

  In another aspect, the first mechanical circuit breaker connected between the first system and the second system, the auxiliary circuit parallelly connected to the first mechanical circuit breaker, and the primary side An alternating current transformer connected between a common connection point of one system and the auxiliary circuit and a common connection point of the second system and the auxiliary circuit, the secondary side being connected to the auxiliary circuit; The auxiliary circuit includes a normally-off first semiconductor switching element whose collector terminal is connected to a common connection point of the first system and the first mechanical circuit breaker, and a common circuit of the second system and the first mechanical circuit breaker. A normally-off second semiconductor switching element in which a collector terminal is connected to a connection point and an emitter terminal is connected to an emitter terminal of the first semiconductor switching element, and a cathode terminal at one end of the secondary side of the alternating current transformer First die connected And a cathode terminal connected to the other end of the secondary side of the alternating current transformer, an anode terminal is connected to an anode terminal of the first diode, and a common connection point thereof is the first and second semiconductor switching devices. A second diode connected to the emitter terminal of the element, and an anode terminal connected to one end of the secondary side of the alternating current transformer, and a third diode having a cathode terminal connected to the gate terminal of the first semiconductor switching element A fourth diode whose anode terminal is connected to the other end of the secondary side of the alternating current transformer and whose cathode terminal is connected to the gate terminal of the second semiconductor switching element; and the gate of the first semiconductor switching element A first Zener diode having a cathode terminal connected to the terminal and an anode terminal connected to the emitter terminal of the first semiconductor switching element; A first resistor connected in parallel to one zener diode, the first zener diode, a first capacitor connected in parallel to the first resistor, and a gate terminal of the second semiconductor switching element A second zener diode having a cathode terminal connected to the second semiconductor switching element and an anode terminal connected to the emitter terminal of the second semiconductor switching element, a second resistor connected in parallel to the second zener diode, and the second zener diode A zener diode and a second capacitor connected in parallel to the second resistor are provided.

  In another aspect, the first mechanical circuit breaker connected between the first system and the second system, the auxiliary circuit parallelly connected to the first mechanical circuit breaker, and the primary side 1 connected between the common connection point of the mechanical circuit breaker and the auxiliary circuit and the first system, or between the common connection point of the first mechanical circuit breaker and the auxiliary circuit and the second system, An alternating current transformer connected on the next side to the auxiliary circuit, wherein the auxiliary circuit is connected to a common connection point of the first system and the first mechanical circuit breaker at a normally off state; A normally-off second of which the collector terminal is connected to the common connection point between the first semiconductor switching element and the second system and the first mechanical circuit breaker, and the emitter terminal is connected to the emitter terminal of the first semiconductor switching element Semiconductor switching element, and the alternating current A first switch connected between one end and the other end of the secondary side of the flow device, a first diode having a cathode terminal connected to one end of the secondary side of the alternating current transformer, and the alternating current transformation current The cathode terminal is connected to the other end of the secondary side of the device, the anode terminal is connected to the anode terminal of the first diode, and the common connection point is connected to the emitter terminals of the first and second semiconductor switching elements A second diode, a third diode whose anode terminal is connected to one end of the secondary side of the AC current transformer, and whose cathode terminal is connected to the gate terminal of the first semiconductor switching element; The fourth diode has an anode terminal connected to the other end of the secondary side, and a cathode terminal connected to the gate terminal of the second semiconductor switching element, and a gate terminal of the first semiconductor switching element. A first Zener diode connected to the diode terminal and the anode terminal to the emitter terminal of the first semiconductor switching element, a first resistor connected in parallel to the first Zener diode, and the first resistor. A cathode terminal is connected to a Zener diode, a first capacitor connected in parallel to the first resistor, and a gate terminal of the second semiconductor switching element, and an anode terminal is connected to an emitter terminal of the second semiconductor switching element , A second resistor connected in parallel to the second Zener diode, the second Zener diode, and a second resistor connected in parallel to the second resistor. And a capacitor.

  In another aspect, the first mechanical circuit breaker connected between the first system and the second system, the auxiliary circuit parallelly connected to the first mechanical circuit breaker, and the primary side Between a common connection point of one system and the auxiliary circuit and a common connection point of the second system and the auxiliary circuit, or a common connection point of the first mechanical circuit breaker and the auxiliary circuit and the first system And an alternating current transformer connected between the common connection point of the first mechanical circuit breaker and the auxiliary circuit and the second system, the secondary side being connected to the auxiliary circuit, The auxiliary circuit includes a normally-off first semiconductor switching element whose collector terminal is connected to a common connection point of the first system and the first mechanical circuit breaker, and a common circuit of the second system and the first mechanical circuit breaker. A collector terminal is connected to the connection point, and an emitter terminal is connected to the first semiconductor A normally-off second semiconductor switching element connected to the emitter terminal of the matching element, a first diode having a cathode terminal connected to one end of the secondary side of the alternating current transformer, and the alternating current transformer A second diode having a cathode terminal connected to the other end on the next side, an anode terminal connected to the anode terminal of the first diode, and a common connection point connected to the emitter terminals of the first and second semiconductor switching elements A third diode whose anode terminal is connected to one end of the secondary side of the alternating current transformer and whose cathode terminal is connected to the gate terminal of the first semiconductor switching element; and the secondary side of the alternating current transformer A fourth diode having an anode terminal connected to the other end of the second semiconductor switching element and a cathode terminal connected to the gate terminal of the second semiconductor switching element; A first Zener diode whose cathode terminal is connected to the gate terminal of the switching element and whose anode terminal is connected to the emitter terminal of the first semiconductor switching element, and a first resistor connected in parallel to the first Zener diode A first capacitor connected in parallel to the first resistor, a fifth diode in which an anode terminal is connected to a gate terminal of the first semiconductor switching element, and (2) A second Zener diode whose cathode terminal is connected to the gate terminal of the semiconductor switching element and whose anode terminal is connected to the emitter terminal of the second semiconductor switching element, and a second terminal connected in parallel to the second Zener diode Parallel to the second resistor, the second Zener diode, and the second resistor And a sixth diode whose anode terminal is connected to the gate terminal of the second semiconductor switching element and whose cathode terminal is connected to the cathode terminal of the fifth diode, and the fifth and sixth capacitors. A third resistor and a second switch are connected in series between the common connection point of the diodes and the emitter terminals of the first and second semiconductor switching elements.

  In one aspect, a series circuit of a fourth resistor and a fifth capacitor is connected in parallel to the first and second semiconductor switching elements.

  In another aspect, a first mechanical circuit breaker connected between the first system and the second system, an auxiliary circuit connected in parallel to the first mechanical circuit breaker, and a primary side of the auxiliary circuit And a second mechanical circuit breaker for detecting an AC current transformer whose secondary side is connected to the auxiliary circuit and interrupting the current passing through the auxiliary circuit, wherein the auxiliary circuit A normally-on first semiconductor switching element whose drain terminal is connected to a common connection point between one system and the first mechanical circuit breaker, and a drain terminal at the common connection point between the second system and the first mechanical circuit breaker A second semiconductor switching element of the normally on in which the source terminal is connected to the source terminal of the first semiconductor switching element, and the anode terminal is connected to one end of the secondary side of the alternating current transformer 1 diode and the above The anode terminal is connected to the other end of the secondary side of the current transformer, the cathode terminal is connected to the cathode terminal of the first diode, and the common connection point is connected to the source terminals of the first and second semiconductor switching elements A second diode, a third diode whose cathode terminal is connected to one end of the secondary side of the alternating current transformer, and a cathode terminal whose other end is connected to the secondary side of the alternating current transformer A fourth reactor, a first reactor and a fifth resistor connected in series between the anode terminal of the third diode and the gate terminal of the first semiconductor switching element, the anode terminal of the fourth diode, and the second semiconductor A second reactor and a sixth resistor connected in series with the gate terminal of the switching element, and an anode terminal of the third diode and an anode terminal of the fourth diode An anode terminal is connected to the gate terminal of the first semiconductor switching element, and the third and fourth capacitors connected in series to each other and whose common connection point is connected to the source terminals of the first and second semiconductor switching elements; A first Zener diode whose cathode terminal is connected to the source terminal of the first semiconductor switching element, a first resistor connected in parallel to the first Zener diode, the first Zener diode, and A second capacitor having a first capacitor connected in parallel with one resistor, an anode terminal connected to the gate terminal of the second semiconductor switching device, and a cathode terminal connected to the source terminal of the second semiconductor switching device Diode, a second resistor connected in parallel to the second Zener diode, and the second resistor And a second capacitor connected in parallel to the second resistor.

  According to the present invention, it is possible to establish the power supply of the gate circuit regardless of the level of the arc of the mechanical circuit breaker without separately providing the power supply for the gate circuit of the semiconductor switching element in the direct current cutoff device.

FIG. 1 is a circuit diagram showing a direct current cut-off device according to a first embodiment. FIG. 6 is a diagram showing a current cutoff operation of the direct current cutoff device in the first embodiment. FIG. 5 is a circuit diagram showing a direct current cut-off device according to a second embodiment. FIG. 7 is a circuit diagram showing a direct current cut-off device according to a third embodiment. FIG. 8 is a circuit diagram showing a direct current cut-off device in a fourth embodiment. FIG. 14 is a diagram showing a current interruption operation of the direct current interruption device in the fourth embodiment.

  Hereinafter, Embodiments 1 to 4 of the direct current cut-off device in the present invention will be described in detail based on FIGS.

Embodiment 1
FIG. 1 shows the direct current cut-off device of the first embodiment. The DC circuit breaker according to the first embodiment includes a first mechanical circuit breaker CB1, a current transformer CT that detects a passing current of the first mechanical circuit breaker CB1, and a current commutating current when the first mechanical circuit breaker CB1 is opened. And an auxiliary circuit 3.

  In FIG. 1, a common connection point of the first system 1 and the first mechanical circuit breaker CB1 is a point A, and a common connection point of the second system 2 and the first mechanical circuit breaker CB1 is a point B.

  A first mechanical circuit breaker CB1 and a primary side of a current transformer CT that detects a passing current of the first mechanical circuit breaker CB1 are connected between points A and B. In FIG. 1, the current transformer CT is connected to the point A, and the first mechanical circuit breaker CB1 is connected to the point B. However, the connection sequence of the current transformer CT and the first mechanical circuit breaker CB1 may be reversed.

  The auxiliary circuit 3 includes first and second semiconductor switching elements T1 and T2, first to fourth diodes D1 to D4, first and second Zener diodes ZD1 and ZD2, and first and second resistors R1 and R2. And first and second capacitors C1 and C2.

  The first and second semiconductor switching elements T1 and T2 are normally-off type, and are connected in parallel to the first mechanical circuit breaker CB1. The collector terminal of the first semiconductor switching element T1 is connected to the point A. The emitter terminal of the first semiconductor switching element T1 is connected to the emitter terminal of the second semiconductor switching element. The collector terminal of the second semiconductor switching element T2 is connected to the point B.

  The secondary side of the current transformer CT is connected to the auxiliary circuit 3. The left side terminal on the secondary side of the current transformer CT is connected to the cathode terminal of the first diode D1. The right side terminal on the secondary side of the current transformer CT is connected to the cathode terminal of the second diode D2. The anode terminals of the first and second diodes D1 and D2 are connected to each other, and the common connection point is connected to the emitter terminals of the first and second semiconductor switching elements T1 and T2.

  The anode terminal of the third diode D3 is connected to the left side terminal on the secondary side of the current transformer CT. The cathode terminal of the third diode D3 is connected to the gate terminal of the first semiconductor switching element T1. The anode terminal of the fourth diode D4 is connected to the right side terminal on the secondary side of the current transformer CT. The cathode terminal of the fourth diode D4 is connected to the gate terminal of the second semiconductor switching element T2.

  A first capacitor C1, a first resistor R1 and a first Zener diode ZD1 are connected in parallel between the gate terminal and the emitter terminal of the first semiconductor switching element T1.

  The cathode terminal of the first Zener diode ZD1 is connected to the gate terminal of the first semiconductor switching element T1, and the anode terminal of the first Zener diode ZD1 is connected to the emitter terminal of the first semiconductor switching element T1.

  A second capacitor C2, a second resistor R2 and a second Zener diode ZD2 are connected in parallel between the gate terminal and the emitter terminal of the second semiconductor switching element T2.

  The cathode terminal of the second Zener diode ZD2 is connected to the gate terminal of the second semiconductor switching element T2, and the anode terminal of the second Zener diode ZD2 is connected to the emitter terminal of the second semiconductor switching element T2.

  When the current flows from the left to the right of the primary side of the current transformer CT, the current is output from the left side terminal of the secondary side of the current transformer CT, and the current flows into the right side terminal.

  FIGS. 2 (a) and 2 (b) show the interrupting operation of the short circuit current. FIG. 2A shows a state from the occurrence of a short circuit to the turn on of the first semiconductor switching element T1. In FIG. 2A, the short circuit current flows from the left to the right.

  The current transformer CT detects a short circuit current and outputs a current to the secondary side. The output current on the secondary side of the current transformer CT is the third diode D3, the gate capacitance of the first semiconductor switching element T1 (between the gate terminal and the emitter terminal of the first semiconductor switching element T1), and the first capacitor C1,1. Via the second diode D2.

  The gate capacitance of the first capacitor C1 and the first semiconductor switching element T1 (the capacitance between the gate terminal of the first semiconductor switching element T1 and the emitter terminal) is charged, and the gate voltage of the first semiconductor switching element T1 (ie, the first capacitor C1 application voltage) turns to the turn ON level, and the first semiconductor switching element T1 turns ON. After the first semiconductor switching element T1 is turned on, the output current on the secondary side of the current transformer CT passes through the first Zener diode ZD1 instead of the gate capacitance of the first semiconductor switching element T1 and the first capacitor C1, 1 Prevent overcharging of the gate of the semiconductor switching element T1.

FIG. 2B shows the operation until the first semiconductor circuit breaker CB1 is opened and the first semiconductor switching element T1 is turned off. The first mechanical circuit breaker from the host controller determined to be a short circuit condition by detecting the short circuit condition with a current sensor (not shown) or the like separate from the current transformer CT. It is performed by the opening command of CB1. (The same applies to Embodiments 2 to 4.)
Since a time delay occurs in the opening operation of the first mechanical circuit breaker CB1, the first semiconductor switching element T1 is already in the ON state when the first mechanical circuit breaker CB1 is opened. Therefore, the short circuit current can be easily commutated to the auxiliary circuit 3 including the first and second semiconductor switching elements T1 and T2, and the arc at the time of opening the first mechanical circuit breaker CB1 can be suppressed.

  When the short circuit current commutation is completed, the detection current of the current transformer CT becomes zero, and the output current on the secondary side of the current transformer CT also becomes zero. The charge stored in the gate capacitance of the first semiconductor switching element T1 and the first capacitor C1 is discharged through the first resistor R1.

  When the discharge progresses, the gate voltage of the first semiconductor switching element T1 (that is, the voltage applied to the first capacitor C1) falls to the turn OFF level, the first semiconductor switching element T1 turns off, and the short circuit current is interrupted. it can.

  The direct current shutoff device according to the first embodiment can shut off current in both directions. When the short circuit current flows from the right to the left, the gate capacitance of the second semiconductor switching element T2 is charged, the second semiconductor switching element T2 is turned ON, and the short circuit current is diverted to the auxiliary circuit 3. Thereafter, the gate capacitance of the second semiconductor switching element T2 is discharged by the second resistor R2, and the second semiconductor switching element T2 can cut off the short circuit current.

  In the first embodiment, it is assumed that an alternating current transformer is used as the current transformer CT. The reason why there is no problem even if using an alternating current transformer will be described. An alternating current transformer can not detect a direct current. However, since the short circuit current is an alternating current value that is proportional to the system voltage and increases with an inclination that is inversely proportional to the system inductance, the short circuit current can be detected by the alternating current transformer, and the first and second semiconductor switching elements T1 and T2 It can be turned on.

When the first mechanical circuit breaker CB1 is opened, the primary side current of the current transformer CT sharply decreases. Therefore, on the secondary side of the current transformer CT, the secondary current of the current transformer CT shown in FIG. A current in the opposite direction to that of the current may occur. However, this current turns on the second semiconductor switching element T2 as shown in FIG. 2 (b). Since the ON / OFF of the second semiconductor switching element T2 is irrelevant to the short circuit current flowing from the left to the right, it does not affect the operation of the DC interrupting device. (In this case, the short circuit current flows to the diode connected in antiparallel to the second semiconductor switching element T2).
If the current transformer CT is an AC current transformer, no current flows on the secondary side of the current transformer CT even if a constant DC current flows. Therefore, in a state in which a constant direct current flows in a normal state, the steady loss generated in the secondary circuit of the current transformer CT can be made zero.

  The points to be noted in the design of the direct current cut-off device of the first embodiment will be described. When a constant rated current continues to flow in the system and no current is output from the secondary side of the current transformer CT, the gate capacitance of the first semiconductor switching element T1 and the first capacitor C1 are completely discharged. In the direct current cut-off device of the first embodiment, charging of the gate capacitance of the first semiconductor switching element T1 and the first capacitor C1 may be completed before a short circuit occurs from this state and the grid current reaches the cut-off threshold. Desired. The current change ratio of the current transformer CT and the capacity of the first capacitor C1 are determined so as to satisfy this condition.

  Depending on the design, there is a possibility that the first semiconductor switching element T1 may misfire when the grid current surges from zero to the rating. However, in the direct current cut-off device of the first embodiment, the first semiconductor switching element T1 may be turned on at the stage where the short circuit occurs and the first mechanical circuit breaker CB1 is opened. Even if the first semiconductor switching device T1 is misfired in a non-shorted state, the impedance of the first mechanical circuit breaker CB1 is substantially zero while the auxiliary circuit 3 has the first semiconductor switching device T1 and the second semiconductor Because of the voltage drop across the anti-parallel diode of the switching element T2, most of the current passes through the first mechanical breaker CB1. Furthermore, since almost no steady state loss occurs in the first mechanical circuit breaker CB1, almost no steady state loss occurs in the DC interrupting device of the first embodiment.

  The turn-off speed of the first semiconductor switching element T1 after the occurrence of a short circuit and opening the first mechanical circuit breaker CB1 is the discharge speed of the gate terminal, that is, the time constant of the first capacitor C1 and the first resistor R1. Dependent.

  This time constant should be longer than the time it takes for the short circuit current to commutate from the first mechanical circuit breaker CB1 to the auxiliary circuit 3. When the time constant is long, the surge voltage generated by the turn-off of the first semiconductor switching element T1 can be reduced, but the switching loss increases due to the decrease of the turn-off speed, and the thermal duty of the first semiconductor switching element T1 increases. In addition, if the disconnection of the short circuit by the first mechanical circuit breaker CB1 is delayed, the short circuit current is increased, and the conduction loss of the first semiconductor switching device T1 is increased.

  If the time constant of the first capacitor C1 and the first resistor R1 is too short, the surge voltage at the turn-off of the first semiconductor switching device T1 increases, which may cause the first semiconductor switching device T1 to be destroyed by overvoltage. In addition, if the turn-off of the first semiconductor switching element T1 starts before the completion of the commutation to the auxiliary circuit 3, the short circuit current returns to the first mechanical circuit breaker CB1 again and fails to shut off. Therefore, it is necessary to set an appropriate first capacitor C1 and a first resistor R1.

  The first Zener diode ZD1 is for preventing gate overcharge. For example, if the first semiconductor switching element T1 is an IGBT with a rated gate voltage ON voltage = 15 V, a Zener diode with a breakdown voltage of 15 V is used.

After the shutoff operation described above is completed and the cause of the short circuit accident is removed to put the DC system into a normal state, the first mechanical circuit breaker CB1 is closed again. (The same applies to Embodiments 2 and 3)
As described above, according to the first embodiment, bidirectional current interruption can be performed. In addition, it is possible to cut off the direct current with almost no arcing. Further, by using the current transformer CT adapted to the system capacity, the short circuit current can be interrupted regardless of the size of the system capacity. Furthermore, a gate drive power supply for the first and second semiconductor switching elements T1 and T2 is not necessary, which makes it possible to miniaturize the direct current cut-off device and reduce the cost.

  In addition, by using an alternating current transformer in the current transformer CT, steady-state loss to a constant load can be suppressed to a low level. In addition, by appropriately designing the time constants of the first and second resistors R1 and R2 and the first and second capacitors C1 and C2 connected in parallel to the first and second semiconductor switching elements T1 and T2, it is ensured. The short circuit current can be cut off.

  In addition, unlike Patent Document 1, the cost can be reduced because the number of required mechanical circuit breakers and current transformers is small. Furthermore, unlike Patent Document 1, the gate circuits of the first and second semiconductor switching elements T1 and T2 can be shared, and the number of parts can be reduced. Therefore, it becomes possible to attain size reduction and cost reduction of a direct current | flow interruption | blocking apparatus.

  Further, unlike Patent Document 1, there is no need to externally input gate signals for the first and second semiconductor switching elements T1 and T2, and a control device for the first and second semiconductor switching elements T1 and T2 is unnecessary. It is. Therefore, it is possible to suppress that the first and second semiconductor switching elements T1 and T2 malfunction due to the noise being superimposed on the signal input from the outside. This improves the reliability of the DC interrupting device. In addition, it is possible to reduce the size and cost of the direct current shutoff device.

  In addition, unlike Patent Document 2, the operation of the first and second semiconductor switching elements T1 and T2 does not require the arc generated at the time of the shutoff operation of the first mechanical circuit breaker CB1, and therefore, regardless of the magnitude of the generated arc. The blocking operation can be performed reliably. Furthermore, unlike Patent Document 2, the arc generated at the time of the shutoff operation of the first mechanical circuit breaker CB1 does not have to be 15 V or more, and selection of the first mechanical circuit breaker CB1 is facilitated.

  Further, unlike the second and third embodiments to be described later, no switch is used in the auxiliary circuit 3, so a control device for the switch is unnecessary. Therefore, it becomes possible to attain size reduction and cost reduction of a direct current | flow interruption | blocking apparatus.

Second Embodiment
The direct current | flow interruption | blocking apparatus of this Embodiment 2 is shown in FIG. The same parts as in the first embodiment are given the same reference numerals, and the description thereof is omitted. In the second embodiment, the position of the primary side of the current transformer CT is changed between the point B and the second system 2. Although the primary side of the current transformer CT is connected between the point B and the second system 2 in FIG. 3, the primary side of the current transformer CT is between the point A and the first system 1 You may connect to The current transformer CT of the second embodiment is not the passing current of the first mechanical circuit breaker CB1, but the sum of the passing current of the first mechanical circuit breaker CB1 and the passing current of the first and second semiconductor switching elements T1 and T2. System current) is detected.

  Further, a first switch SW1 is added in parallel to the first and second diodes D1 and D2 between the left side terminal and the right side terminal on the secondary side of the current transformer CT.

  In the second embodiment, the position of the current transformer CT is moved with respect to the first embodiment. Thereby, the parasitic inductance component included in the current transformer CT can be removed from the path between the point A and the point B in FIG. 3 including the first mechanical circuit breaker CB1. Therefore, the short circuit current easily commutates from the first mechanical circuit breaker CB1 to the auxiliary circuit 3, and the current can be cut off more reliably.

  Further, in the second embodiment, even after the first mechanical circuit breaker CB1 is opened, the current transformer CT continues to detect the short circuit current, and the output current from the secondary side of the current transformer CT is maintained. As a result, the first semiconductor switching element T1 does not turn off. Therefore, even if the time constant of the first capacitor C1 and the first resistor R1 is set short, the first semiconductor switching element T1 is turned off before the short circuit current completes commutation from the first mechanical circuit breaker CB1 to the auxiliary circuit 3 You won't start to do it.

  However, in this state, the first semiconductor switching element T1 can not be turned off, and the short circuit current can not be interrupted. Therefore, the first switch SW1 is connected in parallel to the secondary side of the current transformer CT.

  If the first switch SW1 is turned on when the short circuit current is commutated from the first mechanical circuit breaker CB1 to the auxiliary circuit 3, the output current of the current transformer CT flows through the first switch SW1 and the first semiconductor switching element T1 Charging to the gate capacity of the Thereafter, the gate charge of the first semiconductor switching element T1 is discharged by the first resistor R1, and the gate voltage of the first semiconductor switching element T1 (that is, the applied voltage of the first capacitor C1) falls to the turn OFF level. The semiconductor switching element T1 can be turned off.

  If the time constant of the first capacitor C1 and the first resistor R1 is set short, the turn-off speed of the first semiconductor switching element T1 can be increased, the switching loss of the first semiconductor switching element T1 can be reduced, and the thermal duty is reduced. In addition, since the time taken to shut off can be shortened, adverse effects on surrounding devices can be suppressed.

  The timing at which the first switch SW1 is turned on is after a predetermined time has elapsed since the first mechanical circuit breaker CB1 is opened. Alternatively, it may be determined after detecting the passing current of the first mechanical circuit breaker CB1 and confirming that it has become zero.

  As described above, the direct current shutoff device according to the second embodiment can also perform bidirectional current interruption similarly to the first embodiment, and exhibits the same function and effect as the first embodiment.

  Further, according to the second embodiment, since the parasitic inductance caused by the current transformer CT is removed from the path of the first mechanical circuit breaker CB1 (between point A and point B in FIG. It becomes easy to commutate and can shorten the time from the occurrence of a short circuit to the shutoff.

  Further, even if the resistance values of the first and second resistors R1 and R2 are reduced, the first and second semiconductor switching elements T1 and T2 can be turned on more reliably, and the short circuit current can be cut off more reliably.

  Further, by reducing the resistance value of the first and second resistors R1 and R2, the current cutoff speed of the auxiliary circuit 3 can be increased, and the loss of the first and second semiconductor switching elements T1 and T2 can be reduced. In addition, by performing faster interruption, damage to surrounding devices due to a short circuit failure can be suppressed.

Third Embodiment
The direct current | flow interruption | blocking apparatus of this Embodiment 3 is shown in FIG. The same parts as in the first and second embodiments are given the same reference numerals and the explanation thereof is omitted.

  In FIG. 4, the primary side of the current transformer CT is connected between the point B and the second system 2 as in the second embodiment, but it is connected between the point A and the first system 1. As in the first embodiment, it may be connected between point A and point B.

  The direct current cut-off device of the third embodiment removes the first switch SW1 of the second embodiment. The anode terminal of the fifth diode D5 is connected to the gate terminal of the first semiconductor switching element T1 of the auxiliary circuit 3. The anode terminal of the sixth diode D6 is connected to the gate terminal of the second semiconductor switching element T2. The cathode terminals of the fifth and sixth diodes D5 and D6 are connected to each other, and one end of a third resistor R3 is connected to the common connection point. One end of a second switch SW2 is connected to the other end of the third resistor R3, and the other end of the second switch SW2 is connected to the emitter terminals of the first and second semiconductor switching elements T1 and T2. The connection order of the third resistor R3 and the second switch SW2 may be reversed.

  Further, a fourth resistor R4 and a fifth capacitor C5 are connected in parallel to the first and second semiconductor switching elements T1 and T2.

  In the third embodiment, the first switch SW1 is removed from the second embodiment, and a gate discharge circuit including fifth and sixth diodes D5 and D6, a third resistor R3 and a second switch SW2 is added. .

  The timing at which the second switch SW2 is turned on is the same as that of the first switch SW1 of the second embodiment, and after a predetermined time has elapsed since the first mechanical circuit breaker CB1 was opened, or the first mechanical circuit breaker CB1 It is after detecting the current and confirming that it has become zero. When the second switch SW2 is turned on, the output current on the secondary side of the current transformer CT does not flow to the gates of the first and second semiconductor switching elements T1 and T2, but flows to the third resistor R3 to charge the gate Will stop.

  Further, since the gate charge of the first and second semiconductor switching elements T1 and T2 is discharged through the third resistor R3, the gate voltage of the first and second semiconductor switching elements T1 and T2 falls to the turn OFF level, The first and second semiconductor switching elements T1 and T2 are turned off.

  In the first and second embodiments, when the resistance value of the first and second resistors R1 and R2 is decreased to increase the turn-off speed, the gate charging current also flows to the first and second resistors R1 and R2. As a result, the gate charge may be insufficient when the first mechanical circuit breaker CB1 is opened, and the first and second semiconductor switching elements T1 and T2 may not be turned ON and commutation may fail. As a countermeasure, when the secondary side output current of the current transformer CT is increased, another problem such as an increase in size of the current transformer CT and an increase in steady state loss occurs.

  However, in the third embodiment, the turn-off speed can be determined by the resistance value of the third resistor R3, and the first and second resistors R1 and R2 become irrelevant to the turn-off operation. By setting the resistance values of the first and second resistors R1 and R2 to be large, the first and second semiconductor switching elements T1 and T2 can be turned on reliably at the occurrence of a short circuit, and the resistance value of the third resistor R3 The turn-off speed can be increased by reducing the size.

  However, if the turn-off speed is increased, the surge voltage generated between the collectors and the emitters of the first and second semiconductor switching elements T1 and T2 becomes large, and the overvoltage breakdown is likely to occur. A surge voltage absorption circuit (snubber circuit) consisting of a series connection of five capacitors C5 is added. If the surge voltage falls below the overvoltage breakdown voltage level of the first and second semiconductor switching elements T1 and T2, the fourth resistor R4 and the fifth capacitor C5 may not be connected.

  The first and second resistors R1 and R2 prevent erroneous firing of the first and second semiconductor switching elements T1 and T2 due to leakage current passing through the semiconductor switching element and the snubber circuit when the first mechanical circuit breaker CB1 is opened. Do.

  As described above, the direct current cut-off device according to the third embodiment is also capable of interrupting current in both directions as in the first embodiment, and exhibits the same effects as the first and second embodiments. Moreover, compared with Embodiment 2, this Embodiment 3 can make the resistance value of 1st, 2nd resistance R1, R2 larger, and can interrupt | block a short circuit current more reliably. Further, the current interruption speed of the auxiliary circuit 3 can be adjusted independently of the first and second resistors R1 and R2 by the discharge circuit, and the interruption can be made faster than in the second embodiment.

Fourth Embodiment
FIG. 5 shows the DC interrupting device of the fourth embodiment. The same parts as in the first to third embodiments are given the same reference numerals, and the description thereof is omitted. The fourth embodiment is different from the first embodiment in the following points.

  The first and second semiconductor switching elements T1 and T2 are normally on semiconductor switching elements. The primary side of the current transformer CT is moved between the point A and the first semiconductor switching element T1 so that the current of the auxiliary circuit 3 is detected instead of the passing current of the first mechanical circuit breaker CB1.

  In addition, FET is used for the 1st, 2nd semiconductor switching element T1 and T2 of FIG. The names of the terminals of the FET partially differ from those of the IGBTs used in the first and second semiconductor switching elements T1 and T2 of FIG. The collector terminal of the IGBT corresponds to the drain terminal of the FET. The emitter terminal of the IGBT corresponds to the source terminal of the FET.

  The directions of the anode and cathode terminals of the first to fourth diodes D1 to D4 are reversed.

  A low-pass filter including first and second reactors L1 and L2, third and fourth capacitors C3 and C4, and fifth and sixth resistors R5 and R6 is connected to the outputs of the first to fourth diodes D1 to D4.

  Specifically, the first reactor L1 and the fifth resistor R5 are connected in series between the anode terminal of the third diode D3 and the gate terminal of the first semiconductor switching element T1. The second reactor L2 and the sixth resistor R6 are connected in series between the anode terminal of the fourth diode D4 and the gate terminal of the second semiconductor switching element T2. Third and fourth capacitors C3 and C4 are connected in series between the anode terminal of the third diode D3 and the anode terminal of the fourth diode D4, and the common connection point is the first and second semiconductor switching elements T1 and T2. Connected to source terminal.

  The directions of the first and second Zener diodes ZD1 and ZD2 are reversed.

  A second mechanical circuit breaker CB2 is connected between the point B and the second semiconductor switching element T2.

  In the fourth embodiment, normally-on semiconductor switching elements are used as the first and second semiconductor switching elements T1 and T2. In the standby state, the gate voltages of the first and second semiconductor switching elements T1 and T2 are zero, and the first and second semiconductor switching elements T1 and T2 are maintained in the ON state. Therefore, if the first mechanical circuit breaker CB1 is opened, an arc hardly occurs and the short circuit current is commutated to the auxiliary circuit 3. In addition, the first and second mechanical circuit breakers CB1 and CB2 are closed during normal operation when no short circuit current is generated.

  In the fourth embodiment, after the occurrence of a short circuit, the first mechanical circuit breaker CB1 is first opened. FIG. 6 shows the operation after opening the first mechanical circuit breaker CB1. The current transformer CT detects the short circuit current commutated to the auxiliary circuit 3, and a current is outputted from the secondary side of the current transformer CT to charge the gate of the first semiconductor switching element T1 with a reverse voltage.

  When the gate charging is completed, the gate voltage of the first semiconductor switching element T1 (that is, the applied voltage of the first capacitor C1) turns to the turn OFF level, the first semiconductor switching element T1 turns off, and the short circuit current can be interrupted. .

  After breaking the short circuit current, the second mechanical circuit breaker CB2 is opened to complete the breaking operation. At this time, since no current flows in the second mechanical circuit breaker CB2, no arc occurs. Thereafter, the gate charge of the first semiconductor switching element T1 is discharged by the first resistor R1, the gate voltage of the first semiconductor switching element T1 falls to the turn ON level, and the first semiconductor switching element T1 is turned ON.

  The direct current shutoff device of the fourth embodiment can also perform bidirectional current interruption similarly to the first to third embodiments. When the short circuit current flows from the right to the left, the first mechanical circuit breaker CB1 is opened and the short circuit current is diverted to the auxiliary circuit 3, and then the gate capacitance of the second semiconductor switching element T2 is charged with the reverse voltage (2) The semiconductor switching element T2 can be turned off to cut off the short circuit current.

  In FIG. 5, the primary side of the current transformer CT may be provided between the second semiconductor switching element T2 and the point B. Similarly, the second mechanical circuit breaker CB2 may be provided between the first semiconductor switching element T1 and the point A.

  Attention in design of the direct current cut-off device of the fourth embodiment will be described. When the short circuit current starts to commutate from the first mechanical circuit breaker CB1 to the auxiliary circuit 3, the secondary side output current of the current transformer CT causes the gate capacitance of the first semiconductor switching element T1 or the second semiconductor switching element T2. Reverse voltage charging is started. If gate charging proceeds before completion of commutation, the turn-off of the first and second semiconductor switching elements T1 and T2 starts, and the short circuit current starts to flow again through the first mechanical circuit breaker CB1 and fails to shut off.

  In the fourth embodiment, a low pass filter including the first and second reactors L1 and L2, the third and fourth capacitors C3 and C4, the fifth and sixth resistors R5 and R6 is added, and the secondary side of the current transformer CT Is delayed until the gate is charged after the current is output. The filter delay time is set to be slightly longer than the commutation time.

  After the shutoff operation described above is completed and the cause of the short circuit accident is removed to make the DC system normal, the first mechanical circuit breaker CB1 is closed again, and then the second mechanical circuit breaker CB2 is closed. .

  As described above, according to the fourth embodiment, bidirectional current blocking is possible, and the same operation and effect as the first to third embodiments can be obtained. Further, the following effects are added to the first embodiment according to the fourth embodiment.

  In the normal state in which the first mechanical circuit breaker CB1 is closed, the current does not pass through the auxiliary circuit 3, and no current flows on the secondary side of the current transformer CT. Therefore, no loss occurs in the secondary circuit of the current transformer CT. Therefore, steady-state loss can be reduced to almost zero even in a system where load fluctuations frequently occur.

  Although the present invention has been described in detail with reference to the specific examples described above, it is obvious to those skilled in the art that various variations and modifications are possible within the scope of the technical idea of the present invention. It is natural that such variations and modifications fall within the scope of the claims.

1, 2 ... 1st, 2nd system 3 ... Auxiliary circuit CB 1, CB 2 ... 1st and 2nd mechanical circuit breaker CT ... (AC) current transformer T 1, T 2 ... 1st and 2nd semiconductor switching elements D1 to D6 ... First to sixth diodes ZD1 and ZD2 first to second Zener diodes R1 to R6 first to sixth resistors C1 to C5 first to fifth capacitors SW1 and SW2 first and second switches L1 and L2 ... 1st and 2nd reactors

Claims (6)

A first mechanical circuit breaker connected between the first system and the second system;
An auxiliary circuit connected in parallel to the first mechanical circuit breaker;
The primary side is connected between the first system and the second system, the secondary side is connected to the auxiliary circuit, and the secondary side outputs a current to the auxiliary circuit when the primary side detects a short circuit current. And an alternating current transformer,
The auxiliary circuit is
A reverse series connection is made between the first system and the second system, and when the alternating current transformer detects a short circuit current, an output current on the secondary side of the alternating current transformer is input to the gate terminal. A second semiconductor switching element;
A first capacitor connected between the gate terminal and the emitter terminal of the first semiconductor switching element;
A second capacitor connected between the gate terminal and the emitter terminal of the second semiconductor switching element;
A resistor that discharges the charge stored in the first and second capacitors;
A direct current cut-off device characterized by comprising. A first mechanical circuit breaker connected between the first system and the second system;
An auxiliary circuit connected in parallel to the first mechanical circuit breaker;
An AC current transformer having a primary side connected between a common connection point of the first system and the auxiliary circuit and a common connection point of the second system and the auxiliary circuit, and a secondary side connected to the auxiliary circuit; , And
The auxiliary circuit is
A normally-off first semiconductor switching element whose collector terminal is connected to a common connection point of the first system and the first mechanical circuit breaker;
A normally-off second semiconductor switching element in which a collector terminal is connected to a common connection point of the second system and the first mechanical circuit breaker, and an emitter terminal is connected to an emitter terminal of the first semiconductor switching element;
A first diode whose cathode terminal is connected to one end of the secondary side of the alternating current transformer;
The cathode terminal is connected to the other end of the secondary side of the alternating current transformer, the anode terminal is connected to the anode terminal of the first diode, and the common connection point is the emitter terminal of the first and second semiconductor switching elements. A second diode connected to
A third diode in which an anode terminal is connected to one end of the secondary side of the AC current transformer, and a cathode terminal is connected to a gate terminal of the first semiconductor switching element;
A fourth diode whose anode terminal is connected to the other end of the secondary side of the alternating current transformer, and whose cathode terminal is connected to the gate terminal of the second semiconductor switching element;
A first zener diode having a cathode terminal connected to the gate terminal of the first semiconductor switching element and an anode terminal connected to the emitter terminal of the first semiconductor switching element;
A first resistor connected in parallel to the first zener diode;
The first Zener diode, and a first capacitor connected in parallel to the first resistor;
A second Zener diode in which a cathode terminal is connected to a gate terminal of the second semiconductor switching element and an anode terminal is connected to an emitter terminal of the second semiconductor switching element;
A second resistor connected in parallel to the second Zener diode;
The second Zener diode, and a second capacitor connected in parallel to the second resistor;
A direct current cut-off device characterized by comprising. A first mechanical circuit breaker connected between the first system and the second system;
An auxiliary circuit connected in parallel to the first mechanical circuit breaker;
The primary side is between the common connection point of the first mechanical circuit breaker and the auxiliary circuit and the first system, or between the common connection point of the first mechanical circuit breaker and the auxiliary circuit and the second system An alternating current transformer connected to the secondary side connected to the auxiliary circuit;
The auxiliary circuit is
A normally-off first semiconductor switching element whose collector terminal is connected to a common connection point of the first system and the first mechanical circuit breaker;
A normally-off second semiconductor switching element in which a collector terminal is connected to a common connection point of the second system and the first mechanical circuit breaker, and an emitter terminal is connected to an emitter terminal of the first semiconductor switching element;
A first switch connected between one end and the other end of the secondary side of the alternating current transformer;
A first diode whose cathode terminal is connected to one end of the secondary side of the alternating current transformer;
The cathode terminal is connected to the other end of the secondary side of the alternating current transformer, the anode terminal is connected to the anode terminal of the first diode, and the common connection point is the emitter terminal of the first and second semiconductor switching elements. A second diode connected to
A third diode in which an anode terminal is connected to one end of the secondary side of the AC current transformer, and a cathode terminal is connected to a gate terminal of the first semiconductor switching element;
A fourth diode whose anode terminal is connected to the other end of the secondary side of the alternating current transformer, and whose cathode terminal is connected to the gate terminal of the second semiconductor switching element;
A first zener diode having a cathode terminal connected to the gate terminal of the first semiconductor switching element and an anode terminal connected to the emitter terminal of the first semiconductor switching element;
A first resistor connected in parallel to the first zener diode;
The first Zener diode, and a first capacitor connected in parallel to the first resistor;
A second Zener diode in which a cathode terminal is connected to a gate terminal of the second semiconductor switching element and an anode terminal is connected to an emitter terminal of the second semiconductor switching element;
A second resistor connected in parallel to the second Zener diode;
The second Zener diode, and a second capacitor connected in parallel to the second resistor;
A direct current cut-off device characterized by comprising. A first mechanical circuit breaker connected between the first system and the second system;
An auxiliary circuit connected in parallel to the first mechanical circuit breaker;
Between the common connection point of the first system and the auxiliary circuit and the common connection point of the second system and the auxiliary circuit on the primary side, or the common connection point of the first mechanical circuit breaker and the auxiliary circuit An AC current transformer connected between a first system or between a common connection point of the first mechanical circuit breaker and the auxiliary circuit and the second system, and having a secondary side connected to the auxiliary circuit , And
The auxiliary circuit is
A normally-off first semiconductor switching element whose collector terminal is connected to a common connection point of the first system and the first mechanical circuit breaker;
A normally-off second semiconductor switching element in which a collector terminal is connected to a common connection point of the second system and the first mechanical circuit breaker, and an emitter terminal is connected to an emitter terminal of the first semiconductor switching element;
A first diode whose cathode terminal is connected to one end of the secondary side of the alternating current transformer;
The cathode terminal is connected to the other end of the secondary side of the alternating current transformer, the anode terminal is connected to the anode terminal of the first diode, and the common connection point is the emitter terminal of the first and second semiconductor switching elements. A second diode connected to
A third diode in which an anode terminal is connected to one end of the secondary side of the AC current transformer, and a cathode terminal is connected to a gate terminal of the first semiconductor switching element;
A fourth diode whose anode terminal is connected to the other end of the secondary side of the alternating current transformer, and whose cathode terminal is connected to the gate terminal of the second semiconductor switching element;
A first zener diode having a cathode terminal connected to the gate terminal of the first semiconductor switching element and an anode terminal connected to the emitter terminal of the first semiconductor switching element;
A first resistor connected in parallel to the first zener diode;
The first Zener diode, and a first capacitor connected in parallel to the first resistor;
A fifth diode whose anode terminal is connected to the gate terminal of the first semiconductor switching element;
A second Zener diode in which a cathode terminal is connected to a gate terminal of the second semiconductor switching element and an anode terminal is connected to an emitter terminal of the second semiconductor switching element;
A second resistor connected in parallel to the second Zener diode;
The second Zener diode, and a second capacitor connected in parallel to the second resistor;
A sixth diode in which an anode terminal is connected to a gate terminal of the second semiconductor switching element and a cathode terminal is connected to a cathode terminal of the fifth diode;
A third resistor and a second switch connected in series between the common connection point of the fifth and sixth diodes and the emitter terminals of the first and second semiconductor switching elements;
A direct current cut-off device characterized by comprising.   4. A DC interrupting device according to claim 3, wherein a series circuit of a fourth resistor and a fifth capacitor is connected in parallel to the first and second semiconductor switching elements. A first mechanical circuit breaker connected between the first system and the second system;
An auxiliary circuit connected in parallel to the first mechanical circuit breaker;
An alternating current transformer in which a primary side detects a passing current of the auxiliary circuit and a secondary side is connected to the auxiliary circuit;
A second mechanical circuit breaker for interrupting a current passing through the auxiliary circuit;
Equipped with
The auxiliary circuit is
A normally-on first semiconductor switching element having a drain terminal connected to a common connection point of the first system and the first mechanical circuit breaker;
A normally-on second semiconductor switching element having a drain terminal connected to a common connection point between the second system and the first mechanical circuit breaker, and a source terminal connected to a source terminal of the first semiconductor switching element;
A first diode whose anode terminal is connected to one end of the secondary side of the alternating current transformer;
The anode terminal is connected to the other end of the secondary side of the alternating current transformer, the cathode terminal is connected to the cathode terminal of the first diode, and the common connection point is the source terminal of the first and second semiconductor switching elements. A second diode connected to
A third diode whose cathode terminal is connected to one end of the secondary side of the alternating current transformer;
A fourth diode whose cathode terminal is connected to the other end of the secondary side of the alternating current transformer;
A first reactor and a fifth resistor connected in series between the anode terminal of the third diode and the gate terminal of the first semiconductor switching element;
A second reactor and a sixth resistor connected in series between the anode terminal of the fourth diode and the gate terminal of the second semiconductor switching element;
Third and fourth capacitors connected in series between the anode terminal of the third diode and the anode terminal of the fourth diode, and whose common connection point is connected to the source terminals of the first and second semiconductor switching elements When,
A first Zener diode having an anode terminal connected to the gate terminal of the first semiconductor switching element and a cathode terminal connected to the source terminal of the first semiconductor switching element;
A first resistor connected in parallel to the first zener diode;
The first Zener diode, and a first capacitor connected in parallel to the first resistor;
A second Zener diode in which an anode terminal is connected to a gate terminal of the second semiconductor switching element and a cathode terminal is connected to a source terminal of the second semiconductor switching element;
A second resistor connected in parallel to the second Zener diode;
The second Zener diode, and a second capacitor connected in parallel to the second resistor;
A direct current cut-off device characterized by comprising.

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