Switchgear

Abstract

A switch device (1) comprises: a first contact (6); a second contact (18) disposed in parallel to the first contact; and an accident detection unit (16) that operates the first contact to open when an accident is detected. The second contact includes: a fixed contact element (30) formed of a pair of long energized electrodes facing each other, and provided with a fixed contact; and a movable contact element (32) provided with a movable contact that can contact and not contact the fixed contact. When the second contact is energized by an opening operation of the first contact, the movable contact separates from the fixed contact due to the electromagnetic force caused by currents of opposite directions respectively flowing through the energized electrode pair. A discharge switch (12) is formed between the movable contact and the fixed contact that are separated. Further provided are: a first arc runner (26) that electrically connects with the fixed contact element for driving, by electromagnetic force, the arc discharge occurring when the second contact is opened; and a second arc runner (24) that electrically connects with the movable contact element.

Description

[Technical field]

[0001] The present disclosure relates to switching devices such as switches, switches, circuit breakers, electromagnetic contactors, and relays that open and close electric circuits. [Background technology]

[0002] Conventionally, in a switchgear, in addition to closing or opening an electric circuit by means of electric contacts, etc., it also safely opens an electric circuit when an abnormality such as a short circuit or an overcurrent occurs. As an example, in a switchgear, in order to prevent an increase in current when an abnormality occurs, a first contact is provided in parallel with the first contact, a second contact is provided in parallel with the first contact, a PTC element is provided in series with the second contact, and a current limiting element is provided in parallel with the first and second contacts. The switchgear opens the first and second contacts in sequence when an abnormality occurs. The switchgear normally conducts electricity with little resistance loss through the first contact, and when an abnormality occurs, it transfers the current to a circuit having the second contact and the PTC element as a preliminary step to transferring the current to the current limiting element. This makes it possible to stabilize the transfer of the current to the current limiting element while preventing damage due to arc discharge at the first contact, and to prevent an increase in the current (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2001-515337 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, when connecting electric circuits using a conventional switching device, if an abnormality such as a short circuit occurs in the circuit to be connected, a large current exceeding several kA to several tens of kA may flow.

[0005] In conventional switching devices, when a large current passes through the second contact provided in series with the PTC element, the electromagnetic force generated near the interface of the contact surfaces of the contact pair can cause the contacts to open before the current transfers to the current-limiting element, resulting in an arc discharge that can damage the contacts.

[0006] The present disclosure is intended to solve the above-mentioned problems, and has an object to provide a switching device that is capable of preventing damage to contacts in a simple manner. [Means for solving the problem]

[0007] According to one embodiment, the switchgear includes a first contact, a second contact provided in parallel with the first contact, a discharge switch provided in parallel with the second contact and turned on only when a discharge occurs, and an accident detection unit that opens the first contact when an accident is detected. The discharge switch has a resistance increasing function. The second contact opens when it is turned on, and the discharge generated when the second contact opens is driven to the discharge switch, thereby switching the current path from the second contact to a circuit having the discharge switch. Effect of the Invention

[0008] The switching device according to the present disclosure can prevent damage to the contacts in a simple manner. [Brief description of the drawings]

[0009] [Figure 1] 1A and 1B are diagrams illustrating an external configuration of a switching device 1 according to a first embodiment. [Diagram 2] 1 is a circuit configuration diagram of a switching device 1 according to a first embodiment. [Diagram 3] 1 is a diagram illustrating a main part of a commutation unit 10 according to a first embodiment. [Figure 4] FIG. 10 is a diagram illustrating a main part of a commutation unit 10A according to a second embodiment. [Diagram 5] FIG. 11 is a diagram illustrating a main part of a commutation unit 10B according to a third embodiment. [Figure 6]13 is a diagram illustrating a main part of a second contact 18#A according to a fourth embodiment. FIG. [Figure 7] FIG. 13 is a diagram illustrating a main part of a commutation unit 10C according to a modification of the fourth embodiment. [Figure 8] FIG. 13 is a circuit configuration diagram of a switching device 1A according to a fifth embodiment. [Figure 9] FIG. 13 is a circuit configuration diagram of a switching device 1B according to a modified example of the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Since the names and functions of the components are also the same, detailed description thereof will not be repeated.

[0011] Embodiment 1 Fig. 1 is a diagram illustrating an external configuration of a switchgear 1 according to embodiment 1. With reference to Fig. 1, the switchgear 1 includes, inside a housing 7, an accident detection unit 4, a first contact 6, a commutation unit 10 including a second contact, a current-limiting resistor 2 (2A, 2B), and a contact pressure spring 5B.

[0012] The current-limiting resistor 2 includes current-limiting resistors 2A and 2B. The current-limiting resistors 2A and 2B are connected in series by a resistance-connecting conductor 3.

[0013] One side of the first contact 6 is connected to the commutation unit 10, and the other side is connected via a flexible conductor 5A. The first contact 6 is normally pressed by a pressure spring 5B to be in a closed state. The fault detection unit 4 is disposed on a common conductor where the parallel circuits join.

[0014] The fault detection unit 4 detects the magnetic flux density generated by the current in the conductor, and is composed of a movable core that is driven when a current above a certain level flows, and a fixed core, and the movable core is connected to a first contact 6. The first contact 6 is adapted to be driven together with the movable core.

[0015] When an abnormality occurs in the parallel circuit and the current flowing through the conductor increases, the fault detection unit 4 drives the movable core, which opens the first contact and transfers the current to the commutation unit 10.

[0016] Fig. 2 is a circuit configuration diagram of switchgear 1 according to the first embodiment. With reference to Fig. 2, switchgear 1 includes a first contact 6 and a fault detection unit 4 for controlling an opening and closing operation of first contact 6. Commutation unit 10 is connected in parallel with first contact 6. Current-limiting resistor 2 is connected in parallel with first contact 6 and commutation unit 10.

[0017] The commutation unit 10 includes a discharge switch 12 , a discharge resistor 14 , a contact opening operation unit 16 , and a second contact 18 .

[0018] The second contact 18 is connected in parallel with the first contact 6. The contact opening operation unit 16 maintains the second contact 18 in an open state.

[0019] The discharge switch 12 is connected in parallel with the second contact 18, is turned on only when a discharge occurs, and has a resistance increasing function. Specifically, the discharge switch 12 is connected in series with the discharge resistor 14 and in parallel with the second contact 18. The discharge switch 12 is turned on only when an arc discharge occurs.

[0020] The second contact 18 opens when electricity is applied, and an arc discharge that occurs when the second contact 18 opens is driven to the discharge switch 12, thereby switching the current path from the second contact 18 to a circuit including the discharge switch 12.

[0021] 3 is a diagram illustrating a main part of commutation unit 10 according to embodiment 1. With reference to Fig. 3(A), commutation unit 10 includes a housing 22, terminals TA, TB, and TC, a contact opening operation unit 16, a second contact 18, a contact pressure spring 20, arc runners 24 and 28, and an arc-extinguishing member 26.

[0022] The second contact 18 is composed of a pair of opposing longitudinal current-carrying electrodes, and includes a fixed contactor 30 with a fixed contact, and a movable contactor 32 with a movable contact that comes into contact with and does not come into contact with the fixed contact. The second contact 18 is connected to a connection node between the accident detection unit 4 and the first contact 6 via a terminal TA.

[0023] The movable contact 32 is connected to the pressure spring 20 and is normally pressed to be in contact with the fixed contact 30 for electrical continuity.

[0024] The opening operation portion 16 is connected to the movable contact 32 and performs an opening operation on the second contact. The contact opening operation unit 16 is connected to the connection node between the accident detection unit 4 and the first contact 6 via a terminal TB.

[0025] The arc runners 24, 28 are disposed at the upper and lower parts of the housing 22. The arc runner 24 is connected to the movable contact 32. The arc runner 28 is connected to the fixed contact 30. The arc extinguishing member 26 is provided between the arc runner 24 and the arc runner 28.

[0026] When the second contact 18 is energized by opening the first contact 6, currents flow in opposite directions through the opposing longitudinal current-carrying electrodes of the pair, generating an electromagnetic force that separates the movable contact from the fixed contact.

[0027] Specifically, the second contact 18 is normally kept in a closed state by the pressure spring 20, but when the first contact 6 is opened and current transfers to a circuit having the second contact 18, a current path is formed that passes from the terminal TA through the fixed contact 30 and the movable contact 32 to the terminal TB.

[0028] The fixed contact 30 and the movable contact 32 are each composed of a pair of opposing longitudinally shaped current-carrying electrodes, and when the second contact 18 is energized, currents flow in opposite directions in the current-carrying electrode pair, generating a repulsive force between the current-carrying electrodes. In other words, when the second contact 18 is energized, the repulsive force causes the second contact 18 to automatically and quickly open.

[0029] When the second contact 18 opens, a gap is created between the fixed contact and the movable contact, causing an arc discharge between the contacts, and forming a discharge switch between the fixed contact and the movable contact.

[0030] Due to the contribution of the magnetic field generated between the fixed contact 30 and the movable contact 32 , an electromagnetic force is generated inside the arc discharge, and the arc discharge is driven toward the discharge switch 12 .

[0031] The discharge switch 12 is connected to the arc runner 24 and the arc runner 28, and the driven arc discharge is commutated to the arc runner 24 and the arc runner 28 and is driven toward the tip side of the arc runner 24 and the arc runner 28 and extended.

[0032] The arc discharge occurring between the arc runners 24 and 28 increases in discharge resistance as the arc discharge extends, and the current is suppressed.

[0033] An arc-extinguishing member 26 is provided between the arc runner 24 and the arc runner 28, and the arc-extinguishing member 26, such as an arc-extinguishing plate, provided at the destination of the arc discharge can increase the discharge resistance.

[0034] The configuration of the commutation unit 10 according to the first embodiment makes it possible to increase the electrical resistance in the circuit without using a resistive element such as a PTC element. It is possible to exert a current suppression function even for a large current of several kA to several tens of kA or more without being restricted by the current used by the PTC element.

[0035] In the conventional configuration, when a large current passes through the second contact installed in series with the PTC element, the electromagnetic force generated near the interface of the contact surface of the contact pair can cause the contact to open before the current is transferred to the current limiting element, resulting in damage to the contacts due to arc discharge. To prevent the contacts from opening due to electromagnetic force and avoid damage to the contacts, a strong opening and closing mechanism is required to keep the contacts closed until the current transfer to the current limiting element is completed, which can lead to an increase in the size of the switching device.

[0036] The configuration of the commutation unit 10 according to the first embodiment allows the contacts to open quickly immediately after the second contacts 18 are energized, and allows the provision of an arc runner to limit the current instantly before it increases. Therefore, a strong mechanism for keeping the second contacts closed is not required, and a simple configuration can be achieved without increasing the size of the switching device 1.

[0037] The arc discharge generated at the second contact 18 is driven to and maintained by the discharge switch 12, so that wear on the second contact 18 can be suppressed and the life span of the second contact 18 can be extended.

[0038] The switching device 1 according to the first embodiment is configured such that a current-limiting resistor 2 is provided in parallel with the first contact 6. By providing the current-limiting resistor 2 in parallel, a part of the current is diverted to the current-limiting resistor 2 as the electrical resistance of the discharge switch 12 increases, so that wear of the discharge switch 12 due to arc discharge can be further suppressed.

[0039] Furthermore, when the switching device 1 according to embodiment 1 is used in coordination with other circuit breakers or switches to interrupt a circuit, it is possible to maintain the current limiting effect of the current limiting resistor 2 on the circuit current for a long period of time until the other circuit breakers or switches are opened.

[0040] The commutation unit 10 according to the first embodiment includes a contact opening operation unit 16 that operates the second contact 18 to open the second contact 18 .

[0041] With reference to FIG. 3(B), the contact-opening operation portion 16 includes a connection part 160 connected to the movable contactor 32, a movable core 162, a fixed core 164, and a conducting conductor 166.

[0042] The opening operation unit 16 maintains the open state of the second contact 18. Immediately after energizing the second contact 18, the contacts are quickly opened, but even if the electromagnetic force acting on the movable contactor 32 decreases, the opening operation unit 16 can maintain the open state of the second contact 18 by driving the movable contactor 32.

[0043] In this regard, the contact-opening operation unit 16 may be constituted by an electromagnet having multiple iron cores. The movable core 164 is connected to the movable contact 32 via a connecting part 160 .

[0044] When a current flows through the current-carrying conductor 166 disposed between the iron cores, an attractive force is generated between the iron cores. The attractive force drives the movable iron core 162, and is converted into an opening force for the movable contactor 32.

[0045] In addition, when the second contact 18 is energized, the current flows in the opening operation unit 16 through the current-limiting resistor 2, and therefore, by utilizing the adhesive force of the iron core before the movable contact 32 is completely opened, it is possible to increase the opening speed of the second contact 18.

[0046] By providing the contact opening operation unit 16, the second contact 18 can be continuously maintained in an open state even when the current path shifts from the circuit having the discharge switch 12 to the current limiting resistor 2. This makes it possible to suppress a reduction in the contact opening interval of the second contact 18 and easily ensure an insulating state between the contacts.

[0047] The opening operation unit 16 or the accident detection unit 4 may receive a power signal from a system different from the system to be opened. The opening operation unit 16 or the accident detection unit 4 opens the second contact 18 or the first contact 6 when it receives the other power signal. Specifically, a control power source may be provided separately, and the control power source and the opening operation unit 16 or the accident detection unit 4 may be connected to open the second contact 18 or the first contact 6 using the power of the control power source. The presence or absence of an abnormality may be determined based on information from a sensor such as a current sensor (not shown), and when an abnormality is determined, power may be supplied from the control power source to start the operation of the switching device based on various information. Other sensors may be used instead of a current sensor.

[0048] For example, in this configuration, when connecting the switchgear 1 to a load circuit that generates an inrush current when connecting a circuit such as an electric motor, the first contact 6 or the second contact 18 is opened in advance by the power signal. It is possible to configure a circuit via the current-limiting resistor 2 of the switchgear 1. This makes it possible to connect the load circuit with the inrush current kept small by the current-limiting resistor 2.

[0049] Furthermore, by making it possible to open and close the second contact 18 using a power signal from the different system, a command to release the fault can be received from a source other than the switching device of the present disclosure, eliminating the need for the fault detection unit 4 to determine whether or not to release the fault. This makes it possible to stably control the open holding of the second contact 18 even in cases where a current-limiting resistor set with a large electrical resistance value is installed in parallel and the current after current limiting becomes extremely small.

[0050] Embodiment 2 Fig. 4 is a diagram illustrating a main part of commutation unit 10A according to embodiment 2. Referring to Fig. 4(A), compared with commutation unit 10, it differs in that opening operation unit 16 is replaced with opening operation unit 16A. The other configuration is similar to that described in Fig. 3, and therefore detailed description thereof will not be repeated.

[0051] The contact opening section 16A is composed of a single coil or multiple coils, and operates the second contact 18 to open by utilizing the magnetic flux generated by the coils.

[0052] By configuring the contact opening operation unit 16A with a coil, reactance is generated in the circuit when a current passes through the coil, making it possible to limit the current to a small value.

[0053] A high magnetic flux density is generated around the coil due to the number of turns of the coil and the current passing through it. The magnetic flux density can be used to generate an electromagnetic force, etc., to keep the movable contact 32 open. The contact opening operation unit 16A can increase the speed at which the second contact 18 opens by using the electromagnetic force before the circuit having the discharge switch 12 is energized.

[0054] In addition, when the coil is composed of multiple coils, one coil is electrically connected to the movable contactor 32 and the arc runner 24, and the other coils are connected to a power supply of a separate system so that the opening operation of the movable contactor 32 is performed by a power signal of the separate system.

[0055] It is not necessary that one of the coils is electrically connected to the movable contact 32 or the arc runner 24, and the movable contact 32 may be opened or closed by receiving a power signal from a system different from the system that opens and closes all of the coils.

[0056] When multiple coils are provided, it is possible to perform control involving complex commands by adjusting the timing and conditions for receiving the power signal for each coil.

[0057] As shown in FIG. 4(B) and as in embodiment 1, the contact opening operation unit 16A can also use an iron core, with the coil 168 wound around the fixed iron core 164, and the magnetic flux generated from the coil 168 can be used to operate the movable iron core 162, thereby opening or holding the second contact 18 open.

[0058] Embodiment 3 Fig. 5 is a diagram illustrating a main part of a commutation unit 10B according to the third embodiment. Referring to Fig. 5, compared to commutation unit 10, it differs in that a further component is added to contact pressure spring 20. The rest of the configuration is similar to that described in Fig. 3, and therefore detailed description thereof will not be repeated.

[0059] The diverter 10B further includes a spring energy storage component 21 and a contact pressure adjustment mechanism . Specifically, the contact pressure spring 20 is provided with a spring energy storage component 21 and a contact pressure adjustment mechanism 23 .

[0060] The contact pressure adjustment mechanism 23 has a spring energy storage component 21 that can adjust the amount of energy stored in the contact pressure spring 20 on the opposite side to the position of the movable contact 32 of the contact pressure spring 20, and by adjusting the position of the spring energy storage component 21, it is possible to adjust the amount of contact pressure that presses the movable contact 32.

[0061] Therefore, depending on the magnitude of the contact pressure, it becomes possible to adjust the time difference between when the first contact 6 opens and when the second contact 18 opens, and it becomes possible for the second contact 18 to open after the current has completely shifted from the first contact 6 to the circuit having the second contact 18. If the second contact 18 opens before the current shifts from the first contact 6 to the circuit having the second contact 18, the time until the arc discharge generated when the first contact 6 opens is extinguished becomes longer, and the first contact 6 becomes more likely to wear out. However, according to the third embodiment, it is possible to prevent the duration of the arc discharge generated when the first contact 6 opens from being longer.

[0062] Embodiment 4 Fig. 6 is a diagram illustrating a main part of second contact 18#A according to embodiment 4. Referring to Fig. 6, the difference is that second contact 18 is replaced with second contact 18#A. The other configurations are the same as those of the other embodiments.

[0063] The second contact 18#A is formed in a U-shape. Specifically, the second contact 18#A includes a plurality of fixed contacts and a plurality of movable contacts provided corresponding to the plurality of fixed contacts, respectively.

[0064] As an example, the second contact 18#A includes fixed contacts 30A and 30B and movable contacts 32A and 32B. The second contact 18#A is configured as a contact pair of a fixed contact and a movable contact, and the multiple fixed contacts and movable contacts are connected in series.

[0065] When the circuit having the second contact 18#A is energized, the contacts are opened almost simultaneously. The number of contact pairs of the second contact 18#A may be more than two pairs connected in series.

[0066] Further, arc runners 28A and 28B are provided corresponding to the fixed contacts 30A and 30B, respectively. Further, arc runners 24A and 24B are provided corresponding to the movable contacts 32A and 32B, respectively.

[0067] With the configuration according to the fourth embodiment, when the second contact 18#A having a plurality of contact pairs is opened, a plurality of arc discharges are generated from each of the contact pairs.

[0068] The multiple arc discharges are driven toward the discharge switch 12 by electromagnetic force. Discharge switch 12 is connected to arc runners 24A, 24B and arc runners 28A, 28B, and the driven arc discharge is driven and extended toward the tip sides of arc runners 24A, 24B and arc runners 28A, 28B.

[0069] In the arc discharge occurring between the arc runners 24A, 24B and the arc runners 28A, 28B, the discharge resistance increases as the arc discharge extends, and the current is suppressed.

[0070] At this time, the electrode drop voltage increases with the number of arc discharges that occur, so that the effect of limiting the circuit current can be more effectively achieved.

[0071] Arc-extinguishing members may be provided between the arc runners 24A and 24B and between the arc runners 28A and 28B.

[0072] Fig. 7 is a diagram illustrating a main part of a commutation unit 10C according to a modification of the fourth embodiment. Referring to Fig. 7, the commutation unit 10C is different from the commutation unit 10 in that the second contact 18 is replaced with a second contact 18#B. The second contact 18#B is formed in a straight line rather than a U-shape.

[0073] Specifically, the second contact 18#B includes a plurality of fixed contacts and a plurality of movable contacts provided corresponding to the plurality of fixed contacts, respectively.

[0074] As an example, the second contact 18#B includes fixed contacts 30A, 30B and movable contacts 32A, 32B. The fixed contacts and movable contacts are connected in series to form contact pairs. The movable contacts 32A, 32B are pressed against the fixed contacts 30A, 30B by pressure springs 20A, 20B, respectively.

[0075] When the circuit having the second contacts 18#B is energized, the contacts are opened almost simultaneously. The number of contact pairs of the second contacts 18#B may be more than two pairs connected in series.

[0076] As an example, the fixed contact 30A is disposed on the right side and the fixed contact 30B is disposed on the left side. Arc runners 28A and 28B are provided corresponding to the fixed contacts 30A and 30B, respectively. In addition, arc runners 24A and 24B are provided corresponding to the movable contacts 32A and 32B, respectively.

[0077] An arc-extinguishing member 26A is provided between the arc runner 24A and the arc runner 28A. An arc-extinguishing member 26B is provided between the arc runner 24B and the arc runner 28B.

[0078] According to the configuration of the modified example of the fourth embodiment, when the second contact 18#B having a plurality of contact pairs is opened, a plurality of arc discharges are generated from each contact pair. The plurality of arc discharges are driven toward the discharge switch 12 by electromagnetic force. The discharge switch 12 is connected to the arc runners 24A, 24B and the arc runners 28A, 28B, and the driven arc discharges are driven and extended toward the tip sides of the arc runners 24A, 24B and the arc runners 28A, 28B. The arc discharges generated between the arc runners 24A, 24B and the arc runners 28A, 28B increase in discharge resistance as the arc discharges extend, and the current is suppressed. At this time, the electrode drop voltage also increases with the number of arc discharges generated, so that the effect of limiting the circuit current can be more effectively exhibited.

[0079] Embodiment 5. In the fifth embodiment, a method for stabilizing the commutation control of the current from the first contact 6 to the commutation unit 10 will be described.

[0080] Fig. 8 is a circuit configuration diagram of a switching device 1A according to embodiment 5. Referring to Fig. 8, switching device 1A differs from switching device 1 in that first contact 6 is replaced with a first contact 6A.

[0081] The first contact 6A has two contact pairs arranged in series. However, the contact pairs do not have to be two-point series, and the first contact 6A may have a greater number of contact pairs in series than the second contact 18.

[0082] With the configuration according to the fifth embodiment, even if the second contact 18 opens before the transfer of current from the first contact 6A having multiple contact pairs to the commutation unit 10 is completed, the electrode drop voltage occurring on the first contact 6A having multiple contact pairs is always higher than the electrode drop voltage occurring on the second contact 18, so it is possible to suppress a decrease in the commutation speed of the current from the first contact 6A having multiple contact pairs to the commutation unit 10 and perform stable commutation control. Therefore, it is possible to shorten the duration of the arc discharge occurring when the first contact 6A opens, and also to suppress wear on the first contact 6A.

[0083] In addition, by reducing the difference in contact opening time between the first contact 6A having multiple contact pairs and the second contact 18, even if they are opened almost simultaneously, stable commutation control can be performed due to the difference in electrode drop voltage. This makes it possible to accelerate the transfer of current from the second contact 18 to the discharge switch 12, and by increasing the discharge resistance early, it is possible to quickly limit the circuit current immediately after the occurrence of an abnormality.

[0084] Fig. 9 is a circuit configuration diagram of a switching device 1B according to a modification of embodiment 5. With reference to Fig. 9, switching device 1B differs from switching device 1 in that first contact 6 is replaced with a first contact 6B.

[0085] The first contact 6B is configured by providing a plurality of contact pairs in parallel. Note that the contact pairs do not need to be two-point parallel, and a plurality of contacts may be provided in parallel.

[0086] The multiple contact points may be provided by arranging multiple movable electrodes with contacts in parallel to open and close the electrode, or a single movable electrode may be provided with a contact having a shape with multiple contact points.

[0087] In a configuration according to the modified example of embodiment 5, the contact resistance of a contact point is inversely proportional to the square root of the contact pressure load according to the Holm equation. Therefore, by providing multiple contact points and distributing the load at each contact point, it is possible to reduce the contact resistance.

[0088] Furthermore, by staggering the timing of contact opening at a plurality of contact points, it is possible to limit the location where arc discharge occurs at the time of contact opening.

[0089] Therefore, by devising the material and shape of the contacts that open last, it is possible to provide the following features. For example, by using a high melting point material for the contacts that open last, it is possible to reduce melting damage when an arc discharge occurs, and to prevent deterioration of the first contacts 6B when they are opened and closed. By limiting the opposing area of ​​the contact pair to a small area in the contacts that open last, it is possible to reduce the cross-sectional area of ​​the arc discharge in addition to the electrode drop voltage when the contacts open, and therefore to further increase the voltage drop occurring on the first contacts 6B. It is also possible to stabilize the control of the current commutation from the first contacts 6B to the commutation unit 10.

[0090] In addition, within the scope of the present disclosure, it is possible to freely combine some or all of the embodiments, and it is possible to modify or omit each embodiment as appropriate.

[0091] The configurations exemplified as the above-mentioned embodiments are examples of the configurations of the present disclosure, and may be combined with other known technologies, or may be modified, such as by omitting some parts, without departing from the scope of the present disclosure. In addition, the above-mentioned embodiments may be implemented by appropriately adopting the processes and configurations described in other embodiments.

[0092] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0093] 1, 1A, 1B switchgear, 2, 2A, 2B current limiting resistor, 3 resistance connecting conductor, 4 fault detection section, 5A conductor, 5B, 20, 20A, 20B contact pressure spring, 6, 6A, 6B first contact, 7, 22 housing, 10, 10A, 10B, 10C commutation section, 12 discharge switch, 14 discharge resistor, 16, 16A opening operation section, 18 second contact, 21 spring energy storage part, 23 contact pressure adjustment mechanism, 24, 24A, 24B, 28, 28A, 28B arc runner, 26, 26A, 26B arc extinguishing member, 30, 30A, 30B fixed contact, 32, 32A, 32B movable contact.

Claims

1. A first contact point; a second contact provided in parallel with the first contact; a discharge switch that is connected in parallel with the second contact and is turned on only when a discharge occurs; an accident detection unit that opens the first contact when an accident is detected, The discharge switch has a resistance increasing function, the second contact opens when an electric current is applied, and a current path is switched from the second contact to a circuit having the discharge switch by driving a discharge generated when the second contact opens to the discharge switch; a current limiting resistor provided in parallel with the first and second contacts; a contact opening operation unit connected in series with the current-limiting resistor for maintaining the second contact open when a current is applied due to the second contact being open.

2. The second contact is constituted by a pair of opposing longitudinally shaped current-carrying electrodes, and includes a fixed contactor having a fixed contact, and a movable contactor having a movable contact that is in and out of contact with the fixed contact, When the second contact is energized by opening the first contact, the movable contact is separated from the fixed contact by an electromagnetic force generated by currents flowing in opposite directions through the current-carrying electrode pair, and the discharge switch is formed between the movable contact and the fixed contact when the movable contact and the fixed contact are separated from each other, a first arc runner electrically connected to the fixed contact for driving an arc discharge generated when the second contact is opened by an electromagnetic force; The switchgear of claim 1 , further comprising a second arc runner electrically connected to the movable contact.

3. The switchgear according to claim 2 , further comprising an arc-extinguishing member between the first arc runner and the second arc runner.

4. The switchgear according to claim 1 , wherein the contact-opening operation portion is formed of a single coil or a plurality of coils, and opens the second contact by utilizing a magnetic flux generated in the coil.

5. 2. The switchgear according to claim 1, wherein the contact-opening operation unit is formed of an electromagnet having a plurality of iron cores, and opens the second contact by utilizing an attractive force generated between the iron cores.

6. The opening operation unit is provided so as to be able to receive a current command from an external source, The switchgear according to claim 1 , wherein the opening operation unit opens the second contact in accordance with the external current command.

7. a pressing spring for pressing the movable contact against the fixed contact; The opening and closing device according to claim 2 , further comprising a contact pressure adjustment mechanism that adjusts the contact pressure of the pressure spring.

8. The second contact is A plurality of fixed contacts; The opening and closing device according to any one of claims 1 to 7, further comprising a plurality of movable contacts provided corresponding to the plurality of fixed contacts, respectively.

9. The switchgear according to claim 8 , wherein the plurality of fixed contacts and the plurality of movable contacts are arranged in series.

10. A first contact point; a second contact provided in parallel with the first contact; a discharge switch that is connected in parallel with the second contact and is turned on only when a discharge occurs; an accident detection unit that opens the first contact when an accident is detected, The discharge switch has a resistance increasing function, the second contact opens when an electric current is applied, and a current path is switched from the second contact to a circuit having the discharge switch by driving a discharge generated when the second contact opens to the discharge switch; The first contact has a plurality of contact points; A switching device, wherein the first contact has more contact points than the second contact.

11. The switching device according to claim 10 , wherein the first contact has a plurality of contact points arranged in parallel.

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