HK40087698A

HK40087698A - Direct-current circuit breaker

Info

Publication number: HK40087698A
Application number: HK42023077505.8A
Authority: HK
Inventors: Kohei MATSUMURA; Nobumoto TOYA
Original assignee: 三菱电机株式会社
Priority date: 2019-05-28
Filing date: 2022-08-03
Publication date: 2023-09-15

Description

TECHNICAL FIELD

The present disclosure relates to a DC circuit breaker having an interrupting portion on an arc extinguishing plate thereof.

BACKGROUND ART

A DC circuit breaker includes: a fixed element having a fixed contact; and a movable element having a movable contact that is separable from the fixed contact. The DC circuit breaker performs opening between the contacts, to interrupt current. An arc generated in association with the opening is transferred from the contacts onto arc runners disposed in the vicinity of the contacts and is guided into an arc extinguishing chamber.

A plurality of arc extinguishing plates each formed by retaining a grid on an insulating plate are parallelly disposed at fixed intervals in the arc extinguishing chamber. The arc having arrived in the arc extinguishing chamber is divided by the arc extinguishing plates, and an arc voltage equal to or higher than a power supply voltage of a DC circuit is generated, whereby fault current is limited and interrupted.

Patent Document 3, according to its abstract, states that a switch unit for a DC circuit is disclosed, which includes a first switch contact, and a second switch contact, which is movable between a first position, wherein the first switch contact contacts the second switch contact, and a second position, wherein the second switch contact is separated from the first switch contact. A positioning element to position an arc chute on the switch unit, the arc chute comprises a plurality of substantially parallel metal plates, the positioning element arranged to guide an arc, which is created between the first switch contact and the second switch contact, into the arc chute in an arc displacement direction in order to be extinguished. At least one gas emitting element, wherein at an interruption operation of the circuit breaker at its nominal current, the arc between the first switch contact and the second switch contact vaporizes a portion of the gas emitting layer.

Patent Document 4, according to its abstract, relates to a breaker provided with an arc extinguishing mechanism with magnetic blowing and air-blowing functions, and mainly aims at solving the problems of poor breaking capacity and poor arc extinguishing effect due to the fact that the arc extinguishing mechanism of the breaker only has the magnetic blowing function or the air-blowing function. The breaker comprises a magnetic blowing device and a gas production plate, wherein the magnetic blowing device and the gas production plate are correspondingly arranged between a static contact and an arc extinguish chamber and are used for guiding an electric arc generated when a moving contact is separated from the static contact to the arc extinguish chamber (3). According to the breaker provided with the arc extinguishing mechanism with the magnetic blowing and air-blowing functions, a magnetic blowing mechanism and the gas production plate are also arranged between the static contact and the arc extinguish chamber; and the electric arc generated when the moving contact is separated from the static contact is guided to the arc extinguish chamber, so that the arc extinguishing efficiency is improved; and the breaking capacity is relatively high.

Patent Document 5, according to its abstract, states that, to provide a circuit breaker that improves breaking performance by suppressing return of an arc and maintaining a high arc voltage, it has a stator having a fixed contact and a mover having a movable contact that contacts and separates from the fixed contact. An arc generated between the contacts is guided to an arc extinguishing chamber by an arc runner. A plurality of grids and support plates are laminated in the arc-extinguishing chamber. The grid has cutouts for drawing arcs formed at the ends on the fixed contact and movable contact sides, and has an insulating part that is adjacent to the top of the cutouts and extends in the width direction.

Patent Document 6, according to its abstract, states that an electromagnetic arc extinction apparatus comprises an arc chamber of insulating material and having an axial channel and electrodes aligned with the axis of the arc chamber and adapted to form a quenching arc in the form of a helix. The cavity of the arc chamber is bent along a helix to cause the quenching arc to be moved in a radial direction, the pitch of the cavity is at least times lesser than the diameter of the arc chamber measured over the cross-section thereof. Conductor plates allow movement of arc roots. The apparatus is suitable for use on any desirable alternating- or direct-current circuits and can find use in high-voltage heavy-current switchgear including circuit breakers and fuses.

Patent Document 7, according to its abstract, states that, to break an arc within a short time and facilitate the miniaturization of a DC high speed circuit breaker, on the upper part of an arc chute having a pair of arc hones and arc guides, numbers of short and long vertically slender iron plates are alternately mounted at fixed intervals in such a manner that the lower ends are neatly arranged to constitute a cooling part. When an arc bridges numbers of the arc guides, the arc is blown up by the magnetic flux generated by the coil part of the central arc guide and entered into the cooling part, in which the arc is cooled by numbers of the iron plates, current-decreased, and extinguished within a short time.

CITATION LIST PATENT DOCUMENT

Patent Document 1: Japanese Laid-Open Patent Publication No. 61-190828
Patent Document 2: Japanese Laid-Open Patent Publication No. 62-82616
Patent Document 3: US 2013/037520 A1
Patent Document 4: CN 105 470 067 A
Patent Document 5: JP 6 516078 B1
Patent Document 6: GB 2 020 113 A
Patent Document 7: JP H05 290682 A

SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

In the conventional DC circuit breaker, an arc having arrived on an arc extinguishing plate in the arc extinguishing chamber may flow back in directions toward the contacts during the limitation and the interruption, to cause restrike of an arc. This results in elongation of the time taken to complete interruption and sometimes also leads to failure of interruption.

Considering this drawback, in Patent Document 1 and Patent Document 2, an interrupting portion is provided between contacts and arc extinguishing plates in an arc extinguishing chamber. Consequently, hot gases generated by an arc having arrived in the arc extinguishing chamber are prevented from flowing back in directions toward the contacts. Thus, restrike of an arc in the vicinity of the contacts is inhibited. However, Patent Document 1 and Patent Document 2 have the following problem. That is, control of the flowing direction of an arc which has arrived on, and divided by, an arc extinguishing plate, is not sufficient, and thus backflow of the arc sometimes occurs, to cause failure of interruption.

The present disclosure has been made to solve the above problem, and an object of the present disclosure is to obtain a DC circuit breaker in which an interrupting portion for controlling the flow of an arc is provided on each of arc extinguishing plates in an arc extinguishing chamber, and which has so high interruption performance that no arc flows back from a location on a grid.

SOLUTION TO THE PROBLEMS

According to the present disclosure, a DC circuit breaker as defined in independent claim 1 is provided. Further embodiments of the claimed invention are defined in the dependent claims. Although the claimed invention is only defined by the claims, the below embodiments, examples, and aspects are present for aiding in understanding the background and advantages of the claimed invention.

EFFECT OF THE INVENTION

In the DC circuit breaker according to the present disclosure, the interrupting portion is provided on each of the arc extinguishing plates. Thus, it is possible to obtain so high interruption performance that no arc flows back from a location on any of the arc extinguishing plates.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] FIG. 1 is a schematic cross-sectional view showing the structure of a DC circuit breaker according to embodiment 1.
[FIG. 2] FIG. 2 is a schematic cross-sectional view showing the structure of the DC circuit breaker according to embodiment 1.
[FIG. 3] FIG. 3 is a perspective view of arc extinguishing plates on each of which interrupting portions according to embodiment 1 are formed.
[FIG. 4] FIG. 4 is a perspective view showing the back surface structure of the arc extinguishing plates on each of which the interrupting portions according to embodiment 1 are formed.
[FIG. 5] FIG. 5 is a partial perspective view showing a modification of the arc extinguishing plate on which the interrupting portions according to embodiment 1 are formed.
[FIG. 6] FIG. 6 is a perspective view showing the internal structure of an arc extinguishing chamber according to embodiment 1.
[FIG. 7] FIG. 7 is a conceptual view showing an effect of the interrupting portions according to embodiment 1.
[FIG. 8] FIG. 8 is a schematic cross-sectional view showing the structure of a DC circuit breaker according to embodiment 1.
[FIG. 9] FIG. 9 is a conceptual view showing an effect of interrupting portions according to embodiment 1.
[FIG. 10] FIG. 10 is a perspective view of arc runners on which interrupting portions according to embodiment 2 are formed.

DESCRIPTION OF EMBODIMENTS

The same or corresponding portions in descriptions of embodiments and the drawings are denoted by the same reference characters.

Embodiment 1

The present embodiment will be described mainly with reference to FIG. 1 to FIG. 7. FIG. 1 and FIG. 2 are each a schematic cross-sectional view showing the schematic structure of a DC circuit breaker 100 of the present embodiment. FIG. 1 shows a closed state between contacts, and FIG. 2 shows an opened state between the contacts. FIG. 3 is a perspective view showing several ones taken out from among arc extinguishing plates 15 disposed in an arc extinguishing chamber 14 of the DC circuit breaker 100. FIG. 3 shows a state where interrupting portions 30 are formed on the arc extinguishing plates 15 which are each formed by an insulating plate 13 and grids 12. FIG. 4 shows the back surface structure in FIG. 3. FIG. 5 shows a modification of the arrangement of a grid 12.

FIG. 6 shows the internal structure of the arc extinguishing chamber 14. FIG. 6 shows a structure in which the arc extinguishing plates 15 which are each formed by the insulating plate 13 and the grids 12 and on which the interrupting portions 30 are formed, are stacked. FIG. 7 shows the flows, of hot gases, that are controlled by the interrupting portions 30.

FIG. 1 and FIG. 2 are each a cross-sectional view of the DC circuit breaker 100 of the present embodiment and each show a schematic structure of the device. Of the DC circuit breaker 100 shown in each of FIG. 1 and FIG. 2, the lower portion indicates an interruption mechanism portion 16 and the upper portion indicates the arc extinguishing chamber 14.

FIG. 1 shows the interruption mechanism portion 16 in a closed state between the contacts. In this state, a movable element 4 is pressed by a closing actuator 5 in the leftward direction in FIG. 1, and a movable contact 3 attached to the movable element 4 is in contact with a fixed contact 1 attached to a fixed element 2. This enables electric conduction between an upper conductor 6 and a lower conductor 7.

In the arc extinguishing chamber 14 at the upper portion in FIG. 1, a space is present above the fixed contact 1 and the movable contact 3, and a fixed-side arc runner 10 and a movable-side arc runner 11 are disposed on the left and right sides. Integrated products are disposed so as to be stacked over the fixed-side arc runner 10 and the movable-side arc runner 11. Each integrated product is composed of: grids 12 which have electrical conductivity and have flat plate shapes; an insulating plate 13 on which the grids 12 are disposed and retained; and interrupting portions 30 which are each made of resin and each formed in a projecting shape in the form of a line to prevent backflow of hot gases.

In the present embodiment, each member disposed in the arc extinguishing chamber 14 and composed of the grids 12 and the insulating plate 13 is referred to as an arc extinguishing plate 15. Meanwhile, each portion disposed on the arc extinguishing plate 15 and having a projecting shape in the form of a line is referred to as an interrupting portion 30.

In FIG. 1, the portion enclosed by the broken line in the arc extinguishing chamber 14 represents the arc extinguishing plate 15. In the arc extinguishing plate 15, the grids 12 are attached to the upper surface of the insulating plate 13, and each interrupting portion 30 is further formed on the insulating plate 13 so as to originate from an edge of the arc extinguishing plate 15.

The interrupting portion 30 on the insulating plate 13 can be formed integrally with the insulating plate 13. Alternatively, the interrupting portion 30 can be formed as a separate member and attached on the insulating plate 13.

The order of stacking of the interrupting portion 30, and the insulating plate 13 and the grids 12 which compose the arc extinguishing plate 15, is merely an example, and it is also possible to change the order of the insulating plate 13 and the grids 12 as described later. In addition, although the interrupting portions 30 are formed on the insulating plate 13 in the present embodiment, the interrupting portions 30 can be formed on the grids 12.

It is noted that FIG. 1 shows a closed state, and thus, in this state, electric conduction is present between the fixed contact 1 and the movable contact 3 and no arc has occurred. A flow at the time of generation of an arc will be described with reference to FIG. 2 and the like.

FIG. 2 shows the interruption mechanism portion 16 in an opened state.

When fault current flows through the interruption mechanism portion 16, a detector 8 disposed on the lower conductor 7 detects the fault current, and a latch 9 retaining the movable element 4 is released by the closing actuator 5. Consequently, the movable element 4 retaining the movable contact 3 is moved. Thus, opening occurs between the fixed contact 1 and the movable contact 3 in a state where current is being applied. At the time of the opening, an arc 20 is generated between the fixed contact 1 and the movable contact 3. It is noted that the stage in which the arc 20 is generated in the opened state is referred to as emergence and is, in some cases, distinguished from other stages of the arc 20.

The arc 20 having emerged between the contacts moves between the fixed-side arc runner 10 and the movable-side arc runner 11. This stage is referred to as transference of an arc 21. Then, the arc 21 moves into the arc extinguishing chamber 14 owing to influences of: electromagnetic forces generated by currents flowing through the fixed-side arc runner 10 and the movable-side arc runner 11; and the flows of electrically conductive hot gases. This stage is referred to as travel of an arc 22.

The arc 22 having travelled into the arc extinguishing chamber 14 arrives at intervals between the arc extinguishing plates 15. The stage in which the arc is divided between the plurality of arc extinguishing plates 15 may be referred to as division of an arc 23. If the divided state is maintained, an arc voltage increases to become equal to or higher than a power supply voltage of a circuit. Consequently, limitation and interruption are performed.

In the present embodiment, the interrupting portions 30 are, as shown in FIG. 2, formed on surfaces of the insulating plates 13 of the arc extinguishing plates 15 so as to originate from edges of the arc extinguishing plates 15 in order to prevent the arc 23 from flowing back from the intervals between the arc extinguishing plates 15 and prevent restrike of an arc due to hot gases.

Hereinafter, the arrangement, the structures, functions, and the like of the interrupting portions 30 will be described with reference to FIG. 3 to FIG. 7.

FIG. 3 illustrates the arrangement and the structures of the interrupting portions 30 formed on the insulating plates 13 of the arc extinguishing plates 15. Some of the plurality of arc extinguishing plates 15 disposed in the arc extinguishing chamber 14 have been taken out and shown.

FIG. 4 shows the back surface structure in FIG. 3. FIG. 5 shows a modification of the structure of the arc extinguishing plate 15, in which the arrangement of a grid 12 is changed.

FIG. 6 shows a schematic structure of the arc extinguishing plates 15 disposed in the arc extinguishing chamber 14 and partially shows, together with the schematic structure, the fixed-side arc runner 10, the movable-side arc runner 11, and the like.

As shown in FIG. 6, the interrupting portions 30 are formed on the insulating plates 13 of the arc extinguishing plates 15 in the present embodiment. When each arc extinguishing plate 15 is disposed in the arc extinguishing chamber 14, the arc extinguishing plate 15 is disposed such that the surface on which the interrupting portions 30 are formed faces downward as shown in FIG. 4.

It is noted that FIG. 3 shows that the insulating plate 13 side on which the interrupting portions 30 are formed faces upward for facilitating explanations.

Although each arc extinguishing plate 15 is composed of the grids 12 and the insulating plate 13 and has a structure in which the interrupting portions 30 are formed, no grids 12 can be viewed in FIG. 6 owing to the view angle.

In FIG. 3, a quadrangular opening in which the traveling arc 22 flows is formed at the center of each insulating plate 13. The grids 12 are stacked so as to protrude into the opening. As shown in FIG. 1 and FIG. 2, the opening is located directly above the fixed contact 1 and the movable contact 3. That is, as shown in FIG. 2, the arc 20 generated owing to an opening operation between the fixed contact 1 and the movable contact 3 flows into the opening owing to the flows of hot gases and electromagnetic forces of the fixed-side arc runner 10 and the movable-side arc runner 11. Then, the arc arrives at the intervals between the arc extinguishing plate 15, whereby the arc is divided by the grids 12 disposed on the arc extinguishing plates 15.

As shown in FIG. 3, each interrupting portion 30 is disposed in the form of a line and has a projecting shape. The interrupting portion 30 is attached to the insulating plate 13 by bringing side surfaces of the projecting-shape portion into close contact with the insulating plate 13. According to the invention, the interrupting portion 30 is disposed substantially in a radial pattern so as to originate from an edge of the quadrangular opening formed at the center of the insulating plate 13 of each arc extinguishing plate 15 and so as to face the outer side of the insulating plate 13 and extend to an edge on the outer peripheral side of the arc extinguishing plate 15.

Regarding the locations at which the interrupting portions 30 are to be formed, the interrupting portions 30 are preferably formed in regions in which the grids 12 are disposed on the arc extinguishing plate 15. Specifically, the interrupting portions 30 are preferably formed on the surfaces of the grids 12 stacked on the arc extinguishing plate 15 or at locations that: are present on a surface, of the arc extinguishing plate 15, that is opposite to the surface on which the grids 12 are formed; and correspond to the locations at which the grids 12 are formed.

Further, if the interrupting portions 30 are disposed so as to originate from regions in which the grids 12 protrude into the quadrangular opening in the arc extinguishing plate 15 shown in FIG. 3, an effect of controlling arcs can be improved.

The thickness of each interrupting portion 30 takes the same value as the thickness of each of the grids 12 and the insulating plate 13 so as not to inflict any great influence on the stacking structure when the arc extinguishing plates 15 are disposed in the arc extinguishing chamber 14 in a mutually stacked manner.

Detailed effects of each interrupting portion 30 exhibited when the divided arc 23 flows into the intervals between the arc extinguishing plates 15, will be described later. Since the interrupting portion 30 is disposed in a radial pattern so as to face the outer side of the insulating plate 13, the interrupting portion 30 is advantageous in diffusing hot gases. In addition, the interrupting portions 30 are each bent at an obtuse angle and have bent portions disposed so as to face each other. Thus, projecting portions at the bent portions make it possible to prevent backflow of hot gases. Therefore, reemergence of an arc can be prevented.

FIG. 4 shows the back surface structure of the arc extinguishing plates 15 shown in FIG. 3. In the structure, projecting portions are formed at center portions in the longitudinal direction of the arc extinguishing plates 15 at which no grids 12 are disposed. The effect of controlling the arc 23 is small in the case of using only these projecting portions. However, if the projecting portions are used in combination with the interrupting portions 30 shown in FIG. 3, a favorable effect of controlling the arc can be expected.

FIG. 5 is a modification in which a grid 12 is disposed between the insulating plate 13 and interrupting portions 30. This arrangement also makes it possible to obtain the favorable effect of controlling the arc.

FIG. 7 shows the flows of hot gases and the arc 22 having travelled to the intervals between the arc extinguishing plates 15. An effect of each interrupting portion 30 on the arc 23 divided by the arc extinguishing plates 15, will be described with reference to FIG. 7. Similarly to FIG. 3, FIG. 7 also shows, for explanations, the state in which the surface of the insulating plate 13 of each arc extinguishing plate 15 on which the interrupting portions 30 are formed faces upward. It is noted that the divided arc 23 spreads in all directions such that, since the shape of the insulating plate 13 of the arc extinguishing plate 15 is symmetric about the quadrangular opening at the center, the diffusion of the arc 23 also has symmetry. Considering this, description will be given with the direction being limited to one direction, for facilitating explanations.

The arc 20 having emerged upon the opening between the fixed contact 1 and the movable contact 3 moves and travels into the quadrangular opening portion at the center in FIG. 7. The arc 22 having travelled past the fixed-side arc runner 10 and the movable-side arc runner 11 is influenced by the flows of hot gases and the electromagnetic forces of the grids 12 of the arc extinguishing plate 15 and moves along the white arrow 32 which indicates the travel of the arc 22 in FIG. 7. Consequently, the arc 22 turns into a divided arc 23.

Further, hot gases generated by the arc 23 and having high electrical conductivity move along the surface of the arc extinguishing plate 15 and are diffused in a radial pattern, as indicated by the black arrows 31 which indicate the flows of the hot gases.

If no interrupting portion 30 is disposed on the insulating plate 13, parts of the diffused hot gases may pass around from sides and may move again in directions toward the center of the arc extinguishing plate 15. In this case, a situation in which restrike of an arc or the like occurs is also conceivable. However, as shown in FIG. 7, the interrupting portions 30 which have projecting shapes in the forms of lines bent at obtuse angles and which have the bent portions facing each other are formed on the insulating plate 13 of the arc extinguishing plate 15 so as to originate from edges of the opening at the center and so as to extend to edges on the outer peripheral side of the arc extinguishing plate 15. Thus, hot gases are diffused as indicated by the black arrows 31, and a hot gas passing around from a side is received by one of the bent portions, whereby the hot gas can be diffused in a radial pattern to the outer side of the arc extinguishing plate 15.

By the above features, backflow of the hot gases generated owing to the divided arc 23 can be prevented, and the hot gases can be diffused to the outer side of the arc extinguishing plate 15. Therefore, the hot gases can be ejected to the vicinity of a housing of the arc extinguishing chamber 14. Consequently, restrike of an arc can be prevented, and an interruption characteristic of the DC circuit breaker 100 can be improved.

In the present embodiment 1, each interrupting portion 30 having a bent shape is formed on the lower surface of the insulating plate 13 with use of the same resin material as that of the insulating plate 13. However, the present disclosure is not limited thereto. The same advantageous effects can be obtained also by making an interrupting portion 30 having a linear or bent projecting shape with use of a different insulating material and attaching the interrupting portion 30 to the insulating plate 13 by pasting or screwing.

In addition, although a configuration in which the interrupting portions 30 are attached to the lower surface of the insulating plate 13 of each arc extinguishing plate 15 has been described in the present embodiment, the same advantageous effects can be obtained even when an interrupting portion 30 having a linear or bent projecting shape is formed on the upper surface of the insulating plate 13.

In addition, although each interrupting portion 30 is formed on the insulating plate 13 with use of an insulating material in the present embodiment 1, it is also possible to: form an interrupting portion 30 having a linear or bent projecting shape on each grid 12 of the arc extinguishing plate 15 with use of a metal material; and bring side surfaces of the interrupting portion 30 into close contact with the grid by welding to fix the interrupting portion 30. Alternatively, the interrupting portion 30 can be formed also by half-blanking the grid 12 through press working.

Further, although the arc extinguishing chamber 14 in which each arc extinguishing plate 15 composed of the insulating plate 13 and the grids 12 is disposed horizontally has been used in the present embodiment 1, the same advantageous effects can be obtained by forming the interrupting portions 30 on the insulating plate 13 or the grids 12 in the same manner, also in an arc extinguishing chamber 14 in which each arc extinguishing plate 15 composed of the insulating plate 13 and the grids 12 is disposed in the vertical direction as in a DC circuit breaker 101 shown in a cross-sectional view in FIG. 8.

FIG. 9 shows the flows of hot gases and an arc 22 having travelled to the intervals between the arc extinguishing plates 15 disposed in the vertical direction.

An arc 20 having emerged upon opening between the fixed contact 1 and the movable contact 3 moves and travels into the opening portion at the center in FIG. 9. The arc 22 is influenced by the flows of hot gases and the electromagnetic forces of the grids 12 of each arc extinguishing plate 15 and moves along the white arrow 32 which indicates the travel of the arc 22 in FIG. 9. Consequently, the arc 22 turns into a divided arc 23.

Further, hot gases generated by the arc 23 and having high electrical conductivity can be moved along the surface of the arc extinguishing plate 15 and diffused in a radial pattern, as indicated by the black arrows 31 which indicate the flows of the hot gases.

In the present embodiment 1, the interrupting portions 30 having the bent portions disposed so as to face each other have been used. In addition, an example has been shown in which four interrupting portions 30 originating from edges of the opening at the center and extending to edges on the outer peripheral side are used on one arc extinguishing plate 15. However, since the important point about the interrupting portions 30 formed on the arc extinguishing plate 15 is to move hot gases to the outer side, the shape of each interrupting portion 30 is not limited to a bent shape and a projecting shape in the form of a line. Specifically, a cylindrical shape, a prismatic shape, or the like having proportions that greatly differ in the longitudinal direction and the lateral direction may be employed, and the interrupting portion 30 does not necessarily have to be so long as to extend to an edge on an outer peripheral side. Furthermore, the number of the interrupting portions 30 is also not limited to four and only has to be one or more.

Embodiment 2

In embodiment 1, an example has been shown in which: the plurality of arc extinguishing plates 15 each obtained by superposing the insulating plate 13 and the grids 12 are disposed in the arc extinguishing chamber 14; and the interrupting portions 30 are formed on a surface of the insulating plate 13 or each grid 12.

The present embodiment is basically the same as embodiment 1 in that each interrupting portion 30 is formed so as to originate from an edge of the opening at the center. Meanwhile, the present embodiment is characterized in that interrupting portions 33 are formed so as to be in contact with side surfaces of the fixed-side arc runner 10 and the movable-side arc runner 11.

FIG. 10 is a perspective view of an arc extinguishing plate 15 at a lowermost stage connected to the fixed-side arc runner 10 and the movable-side arc runner 11. FIG. 10 shows a state where the movable contact 3, the movable element 4, and the upper conductor 6 are disposed beneath the arc runners.

The fixed-side arc runner 10 and the movable-side arc runner 11 are fixed to a surface of the arc extinguishing plate 15 such that a part of each arc runner protrudes to the said surface. The interrupting portions 33 having bent shapes are disposed in a radial pattern on the surface of the insulating plate 13 such that end portions of the interrupting portions 33 are connected to the protruding portions of the arc runners.

An arc 20 having emerged upon opening between the movable contact 3 and the fixed contact (not shown) is transferred between the arc runners, and an arc 22 having travelled to a location on the arc extinguishing plate 15 at the lowermost stage shown in FIG. 10 moves in a direction toward the outer periphery owing to the flows of hot gases and electromagnetic force of each grid 12 in the same manner as in FIG. 7. Consequently, the arc 22 turns into a divided arc 23. Further, the arc 23 generates hot gas having high electrical conductivity which is prevented by the interrupting portion 33 from flowing back, to be diffused in a radial pattern in the direction toward the periphery of the insulating plate 13 of the arc extinguishing plate 15.

By the above features, backflow of the hot gases generated owing to the divided arc 23 can be prevented, and the hot gases can be diffused to the outer side of the insulating plate 13 of the arc extinguishing plate 15. Therefore, the hot gases can be ejected to the vicinity of the housing of the arc extinguishing chamber 14. Further, in the present embodiment, a region in the vicinity of each arc runner is a region in which the arc 22 travels at high speed, and thus the effect of preventing the backflow can also be notably obtained. Consequently, restrike of an arc can be prevented, and the interruption characteristic of the DC circuit breaker 100 can be improved.

In the present embodiment, an example has been shown in which the interrupting portions 33 are formed on the insulating plate 13, at the lowermost stage in the arc extinguishing chamber 14, which is connected to the arc runners. However, the present disclosure is not limited thereto, and the same advantageous effects can be obtained also by forming the interrupting portions 33 on the grids 12.

In addition, the disposition locations for the interrupting portions 33 are not limited to such locations that the interrupting portions 33 are in contact with side surfaces of the arc runners, and only has to be locations near the arc runners. Thus, the same advantageous effects are exhibited also by forming the interrupting portions 33 on the inner wall of the arc extinguishing chamber 14 retaining the fixed element 2 and the movable element 4 or on a frame portion forming a circuit breaker body.

In addition, if the interrupting portions 30 formed on the arc extinguishing plate 15 disposed in the arc extinguishing chamber 14 described in embodiment 1 and the interrupting portions 33 disposed on the arc extinguishing plate 15 at the lowermost stage described in the present embodiment so as to be in contact with the side surfaces of the arc runners are used together, restrike of an arc can be further prevented, and the interruption characteristic of the DC circuit breaker 100 can be improved.

DESCRIPTION OF THE REFERENCE CHARACTERS

1 fixed contact
2 fixed element
3 movable contact
4 movable element
5 closing actuator
6 upper conductor
7 lower conductor
8 detector
9 latch
10 fixed-side arc runner
11 movable-side arc runner
12 grid
13 insulating plate
14 arc extinguishing chamber
15 arc extinguishing plate
16 interruption mechanism portion
20 to 23 arc
30 interrupting portion
33 interrupting portion
100, 101 DC circuit breaker

Claims

A DC circuit breaker comprising:
an interruption mechanism portion (16) configured to perform opening between a fixed contact (1) and a movable contact (3), to interrupt DC current;

an arc extinguishing plate (15) obtained by superposing an insulating plate (13) and a grid (12) which has electrical conductivity and has a plate shape; and

an arc extinguishing chamber (14) in which a plurality of the arc extinguishing plates (15) are accommodated in a stacked state at fixed intervals such that edges of the arc extinguishing plates (15) are located above the fixed contact (1) and the movable contact (3), wherein

an interrupting portion (30) having a projecting shape is disposed on either surface of each arc extinguishing plate (15) so as to originate from an edge of the arc extinguishing plate (15), characterized in that

the interrupting portion (30) is disposed in a radial pattern so as to originate from an edge of an opening formed at a center of the arc extinguishing plate (15) and extend to an edge of outer peripheral side of the arc extinguishing plate (15).
The DC circuit breaker according to claim 1, wherein a plurality of the interrupting portions (30) are disposed mutually in a radial pattern.
The DC circuit breaker according to claim 2, wherein the plurality of the interrupting portions (30) are disposed on a surface of the grid (12) formed on each arc extinguishing plate (15) or an opposite surface, of the arc extinguishing plate (15), that corresponds to a region in which the grid (12) is formed.
The DC circuit breaker according to claim 3, wherein
a projecting portion is disposed in addition to the interrupting portions (30), and

the projecting portion is disposed in a region, on the arc extinguishing plate (15), in which the grid (12) is not formed.
The DC circuit breaker according to claim 2, wherein each arc extinguishing plate (15) is accommodated in the arc extinguishing chamber (14) such that a surface of the arc extinguishing plate (15) is oriented in a horizontal direction.
The DC circuit breaker according to claim 5, wherein
the arc extinguishing plate (15) has an opening at a center portion thereof,

an edge, of the arc extinguishing plate (15), that delimits the opening is located above the fixed contact (1) and the movable contact (3), and

the plurality of the interrupting portions (30) are disposed mutually in a radial pattern so as to originate from the edges.
The DC circuit breaker according to claim 6, wherein the plurality of the interrupting portions (30) have shapes of bent lines and are disposed such that bent portions thereof face each other.
The DC circuit breaker according to claim 2, wherein each arc extinguishing plate (15) is accommodated in the arc extinguishing chamber (14) such that a surface of the arc extinguishing plate (15) is oriented in a vertical direction.