JP6143615B2 - DC switch - Google Patents

Description

  The present invention relates to a DC switch having a bidirectional current cutoff function applied to a DC power supply circuit.

In recent years, with the widespread use of solar power generation systems and emergency power supply systems using storage batteries, research and development of switchgear devices that support direct current applied to these systems are progressing.
By the way, in conventional DC-compatible switchgear devices (contact type switches such as electromagnetic contactors, circuit breakers, and earth leakage circuit breakers), contact wear has progressed due to the influence of an arc generated between the contacts during the switching operation. In order to cause malfunction, arc extinguishing countermeasures are an important issue in order to extend the life and reliability of switchgear.

  That is, when the above-mentioned contact switch is applied to a DC circuit, it is difficult to extinguish a DC arc generated between the contacts due to the opening operation of the switch. As one of them, a contactless semiconductor switch is connected in parallel to the main circuit contact of a contact switch, and the main circuit current is commutated to the semiconductor switch when the contact switch is opened. There is known a DC switch in which an arc generated between main circuit contacts of a contact switch is quickly extinguished and the semiconductor switch is turned off to cut off a current (for example, Patent Document 1). reference). This DC switch breaks off the main circuit current flowing through the DC circuit to the semiconductor switch without having to provide an additional arc extinguishing chamber (arc extinguishing grid plate) for arc extinction in the contact switch. It becomes possible to do.

  By the way, in the DC switch disclosed in Patent Document 1, an independent driving power source is required for the gate drive circuit that controls the semiconductor switch to be turned on and off. Therefore, the inventors omitted the independent drive power supply for the gate drive circuit, and instead turned on the semiconductor switch by skillfully using the arc voltage generated between the main circuit contacts when the contact switch was opened. , A DC switch that is controlled to be turned off has been previously proposed (see Patent Document 2), and its configuration is shown in FIGS.

  In the circuit diagram of FIG. 5, 1 is a DC circuit connecting a DC power source and a load (not shown), 2 is a contact type switch such as an electromagnetic contactor connected to the DC circuit 1, and 3 is a contact type switch 2 Is a semiconductor switch (contactless electronic switch) connected in parallel, and (+) and (-) in the figure represent the polarity of the main circuit. Here, the contact type switch 2 includes a double contact type main circuit contact 21 composed of a pair of fixed contacts 2a and 2b and a bridge movable contact 2c, and a switch operating device (for operating an electromagnetic contactor described later). The bridging movable contact 2c of the main circuit contact 21 is driven to the open and closed positions by the electromagnet).

  On the other hand, the semiconductor switch 3 includes a switching element 4 such as an IGBT or a MOS-FET (in the illustrated example, an IGBT is used, hereinafter referred to as “IGBT”), a voltage dividing circuit including resistors 5 and 6, and an overvoltage protection device. The zener diode 7 and the capacitor 8 are combined as shown in the figure, and the gate drive circuit 9 is connected between the gate and emitter of the IGBT 4. The gate drive circuit 9 has a contact point at its signal input terminal (gate resistor 5). It is connected to the bridge movable contact 2c of the type switch 2.

  FIG. 6 is an assembly configuration diagram of a DC switch using an electromagnetic contactor for the contact type switch 2. The assembly of the semiconductor switch 3 is mounted on the top of the electromagnetic contactor. Connected to the main circuit. In the figure, 24 is a frame of an electromagnetic contactor, 25 is an operating electromagnet, 26 is a movable contact support, and 27 is a main circuit terminal.

  Next, the operation of the DC switch shown in FIG. 5 will be described with reference to FIGS. That is, in the energized state in which the contact type switch 2 (electromagnetic contactor) is closed, the main circuit current of the DC circuit 1 is switched from the (+) pole side as indicated by the solid line arrow in FIG. It flows to the (−) pole side through the two main circuit contacts 21. In this energized state, the IGBT 4 is in an OFF state. When the contact switch 2 is opened from this energized state, an arc is generated between the fixed contacts 2a, 2b and the bridge movable contact 2c as shown in FIG. 7B, and an arc voltage is generated between the contacts. To do. Although this arc voltage is determined by the gap length between the contact material and the contact, the arc voltage immediately after opening is about 30 V, and the arc voltage increases as the opening gap increases.

  In this state, the arc voltage generated between the main circuit contacts causes a control current to flow through the gate drive circuit 9 of the IGBT 4 as shown by the dotted arrow in the figure, and the capacitor 8 connected to the gate of the IGBT 4 is connected by the resistors 5 and 6. When charged with the divided voltage and the charge voltage exceeds a predetermined gate threshold value, the IGBT 4 is turned on and switched to the ON state and has been flowing to the main circuit contact 21 of the contact type switch 2 until now. The main circuit current is commutated to the IGBT 4 as shown by the solid line arrow in FIG.

  As a result, the arc generated between the contacts of the contact switch 2 disappears instantaneously. As the arc disappears, the arc voltage between the contacts of the contact switch 2 also disappears, so that the charge of the capacitor 8 is discharged through the resistor 6 of the gate drive circuit 9 as shown by the dotted arrow in FIG. Is done. As a result, the gate voltage between the gate and the emitter of the IGBT 4 is lowered, the IGBT 4 is turned off and turned off, and the main circuit current of the DC circuit 1 is completely cut off as shown in FIG. .

  According to this DC switch, since the gate control of the IGBT 4 is performed using the arc voltage between the contacts generated during the opening operation of the contact switch 2, as described in Patent Document 1 described above. An independent drive power supply for the gate drive and its power supply control are unnecessary, and the control circuit of the semiconductor switch can be simplified.

Japanese Patent Laid-Open No. 8-106839 JP 2013-41882 A

  By the way, the DC switch disclosed in Patent Document 2 is a semiconductor switch 3 connected in parallel to a contact switch 2 and connected to a single IGBT 4 having a polarity matched to the energization direction of the DC circuit 1. The gate control of the semiconductor switch is performed using the arc voltage between the contacts generated during the opening operation of the contact switch 2.

  Therefore, although the semiconductor switch 3 does not require an independent gate drive driving power supply and the control circuit thereof can be simplified, the semiconductor switch 3 is limited in one energization direction.

  On the other hand, a DC circuit in which current flows in the opposite direction between charging and discharging of a storage battery, such as a charging / discharging circuit of a storage battery applied to the emergency power system described above, or system linkage of a distributed DC power supply such as photovoltaic power generation In a DC switch applied to a DC power supply system that performs reverse power flow, a bidirectional current interruption function is required. However, the DC switch described in Patent Document 2 cannot be applied to a DC circuit that requires a bidirectional current cutoff function.

  The present invention has been made in view of the above points, and its object is to provide a semiconductor switch connected in parallel to a contact switch based on the circuit configuration of the DC switch (Patent Document 2) described in FIGS. Direct current with improved function so that it can be applied to storage battery charge / discharge circuits, solar power generation systems, etc., and to prevent malfunction of semiconductor switches after current interruption. It is to provide a switch.

In order to achieve the above object, according to the present invention, a contactless semiconductor switch is connected in parallel to a main circuit contact of a contact switch connected to a DC circuit, and the DC circuit is opened when the contact switch is opened. The main circuit current commutated to the semiconductor switch is extinguished and the arc generated between the main contacts of the contact switch is extinguished, and then the main circuit current commutated to the semiconductor switch is cut off by the semiconductor switch OFF control. In the DC switch
The semiconductor switch is connected in parallel to the main contact of a contact switch as a bidirectional switch comprising two switching elements connected in anti-series and a diode connected in anti-parallel to each switching element, and the gate of the switching element The gate drive circuit applies an arc voltage generated between the main contacts when the contact-type switch is opened to control each switching element of the semiconductor switch ON and OFF, and the gate drive circuit Is connected to an auxiliary contact for disconnection that disconnects the gate of the switching element from the main circuit behind the opening of the main circuit contact of the contact switch (claim 1). can do.
(1) The contact switch is equipped with a main circuit contact and an auxiliary contact for disconnection connected to the gate drive circuit of the semiconductor switch, and the main circuit contact and the auxiliary for disconnection are operated by the contact switch operating device. The contacts are operated to open and close (claim 2).
(2) In the preceding paragraph (1), the wipe amount of the auxiliary contact for disconnection mounted on the contact type switch is set larger than the wipe amount of the main circuit contact, and the auxiliary contact for disconnection when the contact type switch is opened Is opened after the opening of the main circuit contact (claim 3).
(3) As a main circuit contact of the contact type switch, a double contact type contact having two fixed contacts per one pole and a bridge movable contact facing the fixed contact is provided, and the bridge movable contact is provided with a semiconductor. A signal input terminal of a gate drive circuit leading to the gate of the switch is connected.
(4) In the preceding paragraph (3), as the main circuit contact of the contact type switch, two sets of single pole single throw contacts or bridge movable contacts connected in series divided into two poles are provided. The signal input terminal of the gate drive circuit leading to the gate of the semiconductor switch is connected to the connection portion.

According to the DC switch having the above-described configuration, the following effects can be obtained.
(1) Consists of two switching elements (IGBTs) connected in parallel to a main circuit contact of a contact point switch connected to a DC circuit in reverse series and diodes connected in antiparallel to each switching element. By adopting a bidirectional switch, it is possible to open the contact type switch without affecting the direction of energization of the main circuit current flowing in the DC circuit, and without having to provide an independent drive power supply for gate control of the semiconductor switch. Synchronously, the main circuit current of the DC circuit can be commutated from the contact point switch to the bidirectional semiconductor switch and cut off.
(2) Here, by connecting an auxiliary contact for mechanical disconnection to the gate drive circuit of the semiconductor switch and disconnecting the gate of the semiconductor switching element from the main circuit after completion of the cutoff of the main circuit current, It is possible to prevent malfunction of the semiconductor switching element later and improve reliability.
(3) And after mounting the auxiliary contact for disconnection on the contact type switch to operate in conjunction with the main circuit contact, the wipe amount of the auxiliary contact for disconnection is made larger than the wipe amount of the main circuit contact. By setting, when the contact switch is opened, the auxiliary contact for disconnection can be opened after the opening operation of the main circuit contact.
(4) Further, the main circuit contact mounted on the contact switch is provided with a double contact type main circuit contact comprising two fixed contacts per pole and a bridge movable contact facing the fixed contact. Connect the signal input terminal of the gate drive circuit leading to the gate of the semiconductor switch to the bridge movable contact, or provide two sets of single pole single throw contacts connected in series divided into two poles, or the bridge movable contact It is possible to adopt a structure in which the signal input terminal of the gate drive circuit leading to the gate of the semiconductor switch is connected to the connection part between the contacts, and in particular, by adopting the latter structure, the gate signal connection line opens the main circuit contact. , Wiring can be easily performed using the connection terminal of the main circuit contact drawn out from the contact type switch without disturbing the movement of the closing operation.

It is a circuit diagram of the direct-current switch concerning Example 1 of the present invention. FIG. 2 is an operation explanatory diagram at the time of opening in FIG. 1, wherein (a), (b), (c), and (d) are the closed energization state of the contact type switch, the state immediately after the opening operation starts, the semiconductor It is a figure showing the energization path | route of each state after the commutation state to a switch and main circuit current interruption | blocking. It is operation | movement explanatory drawing of the main circuit contact mounted in the contact type switch of FIG. 1, and the auxiliary contact for disconnection, Comprising: (a), (b), (c) is a closing state and the state of opening operation, respectively It is a figure showing the opening and closing state of each contact corresponding to an opening completion state. It is a circuit diagram of a DC switch corresponding to an application example of the present invention. FIG. 10 is a circuit diagram of a conventional DC switch disclosed in Patent Document 2. It is an assembly block diagram of the DC switch which employ | adopted the electromagnetic contactor as the contact type switch of FIG. 5, and mounted the semiconductor switch. FIG. 6 is an explanatory diagram of the operation of FIG. 5, (a), (b), (c), and (d) are each a contact-type switch for closing energization and immediately after the opening operation starts, commutation to the semiconductor switch, opening It is a figure showing the energization course of the main circuit current in each state after a pole end, and the control current of a semiconductor switch.

  Embodiments of a DC circuit breaker according to the present invention will be described below with reference to FIGS. In the drawings of the illustrated embodiment, the same parts corresponding to those in FIGS.

  First, FIG. 1 shows a circuit configuration of a DC switch corresponding to the first embodiment of the present invention. A contact switch 2 connected to the DC circuit 1 in FIG. 1 is, for example, an electromagnetic contactor, and is a double contact main circuit contact comprising fixed contacts 2a and 2b and a bridge movable contact 2c as in FIGS. 21 is mounted, and the main circuit contact 21 is switched between a closed position and an open position by an operating device.

  On the other hand, the semiconductor switch 3 connected in parallel between the main circuit terminals 11 and 12 across the main circuit contact 21 of the contact switch 2 connects the collector terminals so that the energization direction is reversed as shown in the figure. Two IGBTs (semiconductor switching elements) 4-1 and 4-2 connected in reverse series and diodes (FWD) 10-1 and 10-2 connected in reverse parallel to the IGBTs 4-1 and 4-2, respectively. It consists of a bidirectional switch.

  Further, a voltage dividing circuit composed of resistors 5, 6-1, 6-2 between each gate-emitter of the IGBTs 4-1 and 4-2 and the bridge movable contact 2c of the contact switch 2; A zener diode 7 is connected as shown in the figure to form a gate drive circuit 9, and an arc voltage generated between the fixed and movable contacts when the contact switch 2 is opened as described below is used as the gate drive circuit 9. Through the gates and emitters of the IGBTs 4-1 and 4-2.

  Further, in the gate drive circuit 9, mechanical disconnection auxiliary contacts 22 and 23 are connected in series between the resistors 6-1 and 6-2 as shown in the figure, and the main switch commutated to the semiconductor switch 3 is connected. The gates of the IGBTs 4-1 and 4-2 are disconnected from the main circuit by opening the auxiliary contacts 22 and 23 for disconnection after the circuit current is interrupted.

  The disconnecting auxiliary contacts 22 and 23 are assembled to the electromagnetic contactor by using an optional auxiliary contact unit (not shown) attached to the electromagnetic contactor (see FIG. 6). 6, the disconnection auxiliary contacts 22 and 23 are operated to open in conjunction with the main circuit contact 21 by driving the operation electromagnet 25), and the disconnection auxiliary contacts 22 and 23 open the main circuit contact 21. The opening is set to be delayed from the pole operation, and the principle of the delayed opening operation will be described with reference to the schematic diagram of FIG.

  That is, in FIGS. 3A to 3C, a step Δh is provided in the mounting height of the fixed contact between the main circuit contact 21 and the auxiliary contacts 22 and 23 for disconnection, and after the contact begins to contact, The wipe amount, which is the amount of movement until the contact is closed, is set so that the disconnecting auxiliary contacts 22 and 23 are larger than the main circuit contact 21.

  Accordingly, when the contact type switch 2 is opened from the closed position shown in FIG. 3A, the fixed / movable contact of the main circuit contact 21 is first opened (see FIG. 3B), and this is delayed. Thus, the fixed / movable contacts of the auxiliary contacts 22 and 23 for disconnection are separated.

  Next, the operation of current interruption when the DC switch shown in FIG. 1 is opened will be described with reference to FIGS. The illustrated example shows a case where the main circuit terminal 11 is energized with the (+) pole (power supply side) and the main circuit terminal 12 as the (−) pole (load side).

  First, FIG. 2A shows the energized state of the DC circuit 1 with the contact switch 2 closed. In this state, the main circuit current flowing in the DC circuit 1 is changed from the (+) pole side to the (−) pole side. It flows through the main circuit contact 21 of the contact switch 2 as indicated by a solid arrow. In this state, each of the IGBTs 4-1 and 4-2 of the semiconductor switch 3 is in an OFF state.

  When the contact type switch 2 is opened from the energized state of FIG. 2A, the fixed contacts 2a and 2b of the main circuit contact 21 and the fixed / movable contacts are opened as shown in FIG. An arc arc is generated between the bridge movable contact 2c and an arc voltage is generated between the contacts. As a result, the arc voltage, the voltage corresponding to the voltage dividing ratio between the resistor 5 and the resistor 6-2, and the time constant according to the relationship between the resistor 6-2 and the input capacitance (capacitance between the gate and the emitter) of the IGBT 4-2 are used. The voltage between the gate and emitter of the IGBT 4-2 rises to a voltage value limited by the Zener diode 7 (the limit voltage of the Zener diode 7 is set to 15 to 18 V in accordance with the gate threshold voltage of the IGBT), and IGBT4 -2 turns on and switches to the ON state.

  When the IGBT 4-2 is turned on, as shown in FIG. 3C, the main circuit current that has been flowing through the main circuit contact 21 of the contact switch 2 until now is commutated to the circuit of the semiconductor switch 3, As shown in the figure, the main circuit current flows from the branch point A of the main circuit 1 so as to return to the branch point B of the main circuit through the diode 10-1 connected in reverse parallel to the IGBT 4-1, the collector-emitter of the IGBT 4-2, The arc generated at the main circuit contact 21 of the contact switch 2 until now disappears instantaneously.

    In addition, when the arc is extinguished, the voltage applied to the gate of the IGBT 4-2 is the resistances 6-1 and 6 connected in series with the disconnecting auxiliary contacts 22 and 23 between C1 and C2 in the figure. 2 and only the voltage generated at both ends (between C2 and C3 in the figure) of the resistor 6-2. In this state, the voltages generated at both ends of the resistors 6-1 and 6-2 (between C1 and C2 in the figure) are the forward voltage of the diode 10-1 connected in parallel to the IGBT 4-1, and the IGBT 4-2. Is a low voltage of about 2 to 4 V.

  For this reason, the electric charge stored in the input capacitance (gate-emitter capacitance) of the IGBT 4-2 until now is discharged to the resistor 6-2, the gate voltage is reduced, and the IGBT 4-2 is turned off accordingly. Switch to OFF state. Further, when the opening operation of the contact switch 2 proceeds, the auxiliary contacts 22 and 23 for disconnection are opened later than the main circuit contact 21 at the end of the opening stroke as described in FIG. Disconnect the gate from the main circuit.

  As a result, the power source voltage is not applied to the gates of the IGBTs 4-1 and 4-2 after the current interruption of the DC circuit 1, and the IGBTs 4-2 continue to discharge the charges remaining in their input capacitances. The voltage is 0V. Therefore, as shown in FIG. 2D, the IGBT 4-2 is completely turned off, and the interruption of the current flowing through the main circuit is completed.

  Next, a supplementary description will be given of the setting for the gate drive circuit 9 of the semiconductor switch 3 described above. First, when the IGBT is turned on and switched to the ON state in conjunction with the opening operation of the contact switch 2, the voltage applied to the gate is generated between the contacts of the main circuit contact 21 of the contact switch 2. The arc voltage to be generated, the resistance values of the resistors 5, 6-1, 6-2 in the gate drive circuit 9, and the voltage dividing ratio thereof are determined. Therefore, the resistance values of the resistors 5, 6-1 and 6-2, and the voltage dividing ratio thereof are set to values that increase the gate voltage of the IGBT to a predetermined gate threshold voltage upon receiving the arc voltage between the contacts. Set. As a specific example, when the arc voltage generated between the main circuit contacts 21 of the contact switch 2 is 30 V, the resistance value of the resistor 5 and the resistors 6-1 and 6-2 is approximately 1: 1 or the resistor 6 By setting −1, 6-2 to be more than that, it is possible to turn on the IGBT by applying a gate voltage of 15 V or more between the gate and the emitter of the IGBT.

  The turn-on time for the IGBT to transition from the OFF state to the ON state is in the range of several tens of microseconds to several hundreds of microseconds, and the IGBT turn-on is completed within several hundreds of microseconds from the start of the opening operation of the contact switch 2 Set.

  Furthermore, the auxiliary contacts 22 and 23 for disconnection, which are mounted on the contact switch 2 and interlocked with the main circuit contact 21, are opened after the IGBT is turned on and the main circuit current is commutated to the semiconductor switch 3. As described with reference to FIG. 3, the disconnecting auxiliary contacts 22 and 23 are set to perform the opening operation with a delay of several milliseconds from the start of the opening operation of the main circuit contact 21.

  In the case where the gate drive circuit 9 of the semiconductor switch 3 is not provided with the auxiliary contacts 22 and 23 for disconnection described above, when the IGBT 4-2 is switched from the ON state to the OFF state, between C1 and C2 in FIG. Since the power supply voltage of the DC circuit 1 is applied, the gate voltage of the IGBT 4-2 increases again, and the IGBT 4-2 may be re-ignited and the main circuit current cannot be disconnected. By providing the disconnecting auxiliary contacts 22 and 23 as described above, it is possible to reliably prevent such malfunction. In the illustrated embodiment, the gate drive circuit 9 is provided with two sets of disconnecting auxiliary contacts 22 and 23. These auxiliary disconnecting contacts are in the OFF state of the IGBT and are C1-C2 in FIG. 2C. This is intended to prevent the occurrence of a power supply voltage between them, and the same malfunction prevention function can be achieved with only one of the auxiliary contacts 22 and 23 for disconnection.

  In the operation description of FIG. 2, the case where the main circuit terminal 11 of the DC circuit 1 is energized with the (+) pole and the terminal 12 as the (−) pole has been described. When energizing from the main circuit terminals 12 to 11, a series of operations for switching and shutting off the main circuit current by switching the IGBT 4-1 to the ON state during the opening operation of the contact switch 2 in the reverse manner. By performing the operation, the bidirectional current can be cut off without being influenced by the energization direction of the main circuit current.

  Next, application examples of the present invention are shown in FIGS. That is, the contact type switch 2 (see FIG. 1) connected to the DC circuit 1 in the first embodiment described above is a dual circuit in which the main circuit contact 21 is composed of the fixed contacts 2a and 2b and the bridge movable contact 2c per pole. As a contact, an input terminal of the gate signal of the semiconductor switch 3 is connected to the bridge movable contact 2c so that an arc voltage between the contacts generated in the opening operation is taken out.

  4 (a) and 4 (b), on the other hand, as a main circuit contact mounted on the contact switch 2, two sets of single poles are divided into two poles and connected in series with each other. Single throw contacts 21-1 and 21-2 are provided, and a drive signal input terminal leading to the gates of the IGBTs 4-1 and 4-2 is connected to a connection portion (point D in the figure) between the contacts. . Here, in FIG. 4A, the contacts 21-1, 21-2 are one-sided contacts, and each contact has one contact composed of a fixed contact and a movable contact. Moreover, in FIG.4 (b), it is a double contact, and has 2 contacts which consist of a bridge movable contact and a fixed contact per pole.

  That is, in the embodiment of FIG. 1, since it is necessary to directly connect the gate drive signal input terminal to the bridging movable contact 2c (movable member) of the main circuit contact 21, a small electromagnetic switch is used as the contact switch 2. When using a contactor, etc., it is difficult to connect and wire the gate drive signal input terminal to the bridged movable contact due to restrictions on the switch structure, and the connection lead wire opens and closes the movable contact. There is a risk of hindering movement. On the other hand, in the contact type switch 2 of FIGS. 4A and 4B, it is necessary to provide two sets of single-pole single-throw contacts 21-1 and 21-2 in two poles. It is possible to easily connect the lead wire of the gate signal input terminal via the connection terminal of each pole drawn out from the switch, and there is no possibility that the connection lead wire hinders the movement of the contact opening / closing operation of the switch.

DESCRIPTION OF SYMBOLS 1 DC circuit 11,12 Main circuit terminal 2 Reed switch 21, 21-1, 21-2 Main circuit contact 22, 23 Auxiliary contact for disconnection 3 Semiconductor switch 4-1, 4-2 IGBT (switching element)
5,6-1,6-2 Resistance 7 Zener diode 10-1, 10-2 Diode arc Arc

Claims (5)

A contactless semiconductor switch is connected in parallel to the main circuit contact of the contact switch connected to the DC circuit, and the main circuit current of the DC circuit is commutated to the semiconductor switch when the contact switch is opened. In a DC switch that extinguishes the arc generated between the main contacts of the switch and cuts off the main circuit current commutated to the semiconductor switch by the OFF control of the semiconductor switch.
The semiconductor switch is connected in parallel to the main contact of a contact switch as a bidirectional switch comprising two switching elements connected in anti-series and a diode connected in anti-parallel to each switching element, and the gate of the switching element The gate drive circuit applies an arc voltage generated between the main contacts when the contact-type switch is opened to control each switching element of the semiconductor switch ON and OFF, and the gate drive circuit The DC switch is characterized in that an auxiliary contact for disconnection for disconnecting the gate of the switching element from the main circuit is connected with delay after the opening of the main circuit contact of the contact switch.   2. The DC switch according to claim 1, wherein the contact type switch is equipped with a main circuit contact and an auxiliary contact for disconnection connected to the gate drive circuit of the semiconductor switch, and the main circuit is operated by the operating device of the contact type switch. A DC switch characterized in that the contact and the auxiliary contact for disconnection are operated to open and close.   3. The DC switch according to claim 2, wherein the wiping amount of the auxiliary contact for disconnection mounted on the contact type switch is set larger than the wiping amount of the main circuit contact, and the auxiliary for disconnection is opened when the contact type switch is opened. A DC switch characterized in that the contact is opened after the opening of the main circuit contact.   The DC switch according to any one of claims 1 to 3, wherein the main circuit contact of the contact switch is a dual switch comprising two fixed contacts per pole and a bridge movable contact facing the fixed contact. A DC switch comprising a contact-type contact, and a signal input end of a gate drive circuit connected to a gate of a semiconductor switch connected to the bridge movable contact.   4. The DC switch according to any one of claims 1 to 3, wherein two sets of single-pole single-throw contacts connected in series divided into two poles or movable as a bridge as a main circuit contact of a contact switch A DC switch comprising a contact and a signal input terminal of a gate drive circuit connected to a gate of a semiconductor switch connected to a connection portion between the contacts.