WO2022259347A1

WO2022259347A1 - Dc circuit breaker

Info

Publication number: WO2022259347A1
Application number: PCT/JP2021/021668
Authority: WO
Inventors: 康平松村; 央佐々木; 知裕仲田
Original assignee: 三菱電機株式会社
Priority date: 2021-06-08
Filing date: 2021-06-08
Publication date: 2022-12-15
Also published as: JP7031083B1; JPWO2022259347A1; EP4354480A1

Abstract

In this DC circuit breaker, it is effective, when breaking, to quickly commutate an arc generated between contacts to an arc runner in order to shorten breaking time and extend the lifetime of the circuit breaker by reducing the amount of wear of the contacts. However, it is difficult to achieve high-speed commutation over the entire range from a small current region at or below the rated value to a large current region of the short-circuit current. Therefore, by forming a fixed side arc runner (12) in a shape that covers the surroundings of a fixed contact (1), an arc can be commutated at a high speed from the small current region to the large current range, and thus breaking performance can be improved.

Description

DC circuit breaker

This application relates to a DC circuit breaker.

A DC circuit breaker consists of a stator with a fixed contact, a mover with a movable contact that can be brought into and out of contact with the stator, an arc runner that transfers the arc generated between the contacts from the contact, and an arc extinguishing chamber that extinguishes the arc. , and the arc runners are arranged in the vicinity of the stator and the mover, respectively.

With this configuration, the arc generated between the contacts due to the contact opening when the current is interrupted is commutated from the contact to the arc runner, and is driven to the arc extinguishing chamber by running the arc runner, where it is connected to the grid in the arc extinguishing chamber. Current-limiting cut-off is performed against the generation of an arc voltage higher than the power supply voltage of the DC circuit by entering and dividing.

In a DC circuit breaker, by quickly commutating the arc that occurs between the contacts during interruption to the arc runner and driving it to the arc extinguishing chamber, the interruption time can be shortened and contact wear can be reduced, resulting in longer life. be done. For this reason, a configuration is known in which a projection is provided on the fixed-side arc runner to quickly commutate the ignited arc from the contact to the arc runner (see, for example, Patent Document 1).

JP 2010-170876 A

However, the above-mentioned arc runner structure can be expected to be effective in the low current range below the rated current where the arc is difficult to commutate from the contact to the arc runner. Regarding commutation, the effect of shortening the commutation time due to the shape of the commutation destination is small, and there is a problem that it is difficult to improve the commutation and running performance over the entire range from small current to large current due to the shape of the arc runner.

The present application has been made to solve the above problems, and an object thereof is to provide a DC circuit breaker equipped with an arc runner that can obtain high breaking performance by shortening the commutation time. do.

The DC circuit breaker disclosed in the present application includes a stator having a fixed contact, a movable element having a movable contact that can be brought into and out of contact with the fixed contact, and a fixed contact and the movable contact arranged near the fixed contact and the movable contact. The fixed contact has an end surface connected to the fixed arc runner and a side surface adjacent to the end surface, and the end surface of the fixed contact and the side surface adjacent to the end surface. A fixed side arc runner is formed so as to cover the side surface.

According to the DC circuit breaker disclosed in the present application, the driving force in the direction of the arc runner on the fixed side is strengthened by generating an offset magnetic flux for the arc that has occurred, and the commutation time is shortened, resulting in high breaking performance. Obtainable.

It is a sectional view showing an outline of the whole composition of a direct-current circuit breaker. FIG. 4 is a cross-sectional view showing movement of an arc in the breaking process of the DC circuit breaker; FIG. 2 is a perspective view of a stator and stationary-side arc runners according to Embodiment 1; FIG. 4 is a cross-sectional view of the stator and fixed-side arc runner of FIG. 3 taken along the line AA; FIG. 4 is a front view of the stator and the fixed-side arc runner according to Embodiment 1 as seen from the contact contact surface side; FIG. 7 is a cross-sectional view of a stator and a stationary-side arc runner according to Embodiment 2; FIG. 11 is a cross-sectional view of a stator and fixed-side arc runners according to Embodiment 3; FIG. 11 is a perspective view of a stator and stationary-side arc runners according to Embodiment 4; FIG. 11 is a perspective view of a stator and stationary-side arc runners according to Embodiment 5; FIG. 10 is a cross-sectional view of the stator and fixed-side arc runner of FIG. 9 taken along the line AA;

Preferred embodiments of the DC circuit breaker according to the present application will be described below with reference to the drawings. The same reference numerals are assigned to the same contents and corresponding parts, and detailed description thereof will be omitted. In the following embodiments as well, redundant descriptions of the configurations denoted by the same reference numerals will be omitted.

Embodiment 1.
FIG. 1 is a cross-sectional view showing the outline of the overall configuration of the DC circuit breaker according to Embodiment 1, FIG. 2 is a cross-sectional view showing the movement of the arc in the breaking process of the DC circuit breaker, and FIG. FIG. 4 is a perspective view showing an element and a fixed-side arc runner, and FIG. 4 is a cross-sectional view taken along line AA of FIG.

First, the configuration of the DC circuit breaker will be explained. The DC circuit breaker comprises a stator 3 composed of a fixed contact 1 and a fixed contact base 2, and a movable element 6 composed of a movable contact 4 and a movable contact base 5 which can be brought into and out of contact with the fixed contact 1. When current is applied, the mover 6 moves toward the stator by the closing actuator 7 and comes into contact with the upper conductor 8 connected to the stator 3 and the lower conductor connected to the mover 6 A current is passed through 9 and .

When an accident current flows at the time of current interruption, the detector 10 arranged in the lower conductor 9 operates by detecting the accident current, and the latch 11 holding the mover 6 is released to release the mover 6. is separated from the stator 3 and the opening operation is performed.

When an opening operation is performed during current interruption, an arc 16 shown in FIG. 2 is generated between the fixed contact 1 and the movable contact 4 (hereinafter referred to as arcing). The arc 16 generated between the contacts is generated by a fixed arc runner 12 arranged near the stator 3 (fixed contact 1) and a movable arc runner 13 arranged near the mover 6 (movable contact 4). , as indicated by arc 17 (hereinafter referred to as commutation). After that, the arc 17 generated between the fixed side arc runner 12 and the movable side arc runner 13 is generated by the electromagnetic force due to the current flowing through each arc runner or the conductive hot gas generated at the time of arc ignition. It travels as indicated by arc 18 in a direction away from the contacts due to flow.

The arc 18 enters the arc extinguishing chamber 15 in which a large number of grids 14 made of a thin plate-like magnetic material are arranged, as indicated by the arc 19. The arc 19 is divided by the grid 14, and the arc voltage rises. When the current exceeds the power supply voltage of the circuit, the current limiting cutoff is performed. Thus, the arc 16 generated by opening the movable contact 4 is commutated to the fixed side arc runner 12, travels in the opposite direction to the contact, and then enters the grid 14 to be cut off.

Next, the structure of the stationary arc runner 12 will be described with reference to the perspective view and AA sectional view of the stationary arc runner 12 shown in FIGS. In the figure, parts other than the arc runner 12 on the fixed side and the stator 3 are omitted, and the aspect of the arc is also shown by cutting only the fixed side.

3 and 4, a fixed contact 1 made of a silver alloy, a fixed contact base 2 made of copper, and a fixed side arc runner 12 made of iron are brazed so as to come into contact with each other. ing. The fixed contact 1 has an end surface 1a (hereinafter referred to as an upper surface) connected to the fixed-side arc runner 12 and a side surface 1b adjacent to the upper surface 1a. A side surface 1b of the fixed contact 1 faces a fixed-side arc runner 12, and the fixed-side arc runner 12 is formed so as to cover the upper surface 1a and the side surface 1b of the fixed contact 1. As shown in FIG.

Next, the operation and effects of the stationary arc runner 12 will be described. When the arc 16 is ignited, an electromagnetic force is generated from the fixed contact 1 toward the fixed-side arc runner 12 due to the self-magnetic field of the main circuit current path. The arc 16 receiving the electromagnetic force extends from the fixed contact 1 to the fixed side arc runner 12 side, and the arc point is commutated from the fixed contact 1 to the fixed side arc runner 12 .

In this structure, not only the electromagnetic force due to the self-magnetic field, but also the biased magnetic flux can be generated by forming the fixed-side arc runner 12, which is a magnetic material, up to the periphery of the fixed contact 1. More specifically, the fixed-side arc runner 12 is shaped to cover the side surface 1b of the fixed contact 1 from the top of the fixed contact 1, that is, the fixed-side arc runner 12 covers the fixed contact 1 from the top in a U-shape. Therefore, it has a structure that utilizes the biased magnetic flux.

FIG. 5 shows a view of the fixed side arc runner 12 from the contact surface side of the fixed contact 1 . A current generated by an arc 16 generated between the fixed contact 1 and the movable contact 4 flows toward the front side 20 of the paper surface in FIG. When a magnetic body (stationary arc runner 12) is placed in the vicinity of the generated magnetic flux 21, the magnetic flux passes through the magnetic body with high magnetic permeability, and the magnetic flux that is originally concentric with the current is biased ( deviation) occurs. As a result, an electromagnetic force 22 is generated in the arc through which the current is flowing in the direction of the fixed-side arc runner 12, and the commutation time can be shortened due to rapid extension of the arc.

The reason why the side surface 1b of the fixed contact 1 is covered with the fixed side arc runner 12 is to generate a larger deviation of the magnetic flux and increase the electromagnetic force. The fixed-side arc runner 12 may cover at least a part of the side surface 1b of the fixed contact 1. However, if the length of the side portion covering the fixed contact 1 of the fixed-side arc runner 12 is lower than the lower part of the contact, an arc will occur. The magnetic flux at locations lower than the position also passes through the stationary arc runner 12, and the electromagnetic force in the direction of the stationary arc runner 12 is reduced. Therefore, it is desirable that the length of the side portion of the fixed contact 1 by the fixed-side arc runner 12 is up to the intermediate position of the contact, which is about the arc firing position.

In addition, the upper portion (upper surface 1a) of the fixed contact 1 is brazed so as to come into contact with the fixed-side arc runner 12. The arc generated between the contacts is commutated to the fixed-side arc runner 12, but if there is a step or gap between the fixed contact 1 and the fixed-side arc runner 12, the commutation is not performed smoothly, resulting in a decrease in breaking performance. Or it may lead to failure of cutoff. Therefore, by bringing the upper portion of the fixed contact 1 into contact with the fixed-side arc runner 12, a structure is adopted in which the commutation is promoted.

Also, it is desirable that the contact direction height of the side portion of the fixed contact 1 of the fixed side arc runner 12 is flush with the contact contact surface or lower than the contact contact surface. When the side surface of the fixed contact 1 of the fixed side arc runner 12 is set higher than the contact contact surface and arranged at a position closer to the movable contact 4 than the fixed contact 1, the contact opening distance between the mover 6 and the stator 3 becomes equal to that between the contacts. It becomes shorter than the distance, the withstand voltage performance is deteriorated, and there is a possibility that the movable contact 4 contacts the fixed-side arc runner 12 at the time of closing, resulting in poor conduction.

The height of the contact contact surface of the fixed contact 1 (the surface that contacts and separates from the movable contact 4) means the height from the lower surface of the fixed contact 1 (the surface opposite to the contact contact surface). In addition, the height of the portion of the fixed-side arc runner 12 covering the side surface 1b of the fixed contact 1 is determined using a plane including the lower surface of the fixed contact 1 as a reference plane, and the contact direction (left side in FIG. 4) from this reference plane. direction).

As described above, according to the present embodiment, the end surface (upper surface) of the fixed contact 1 and the side surface adjacent to the upper surface are covered with the fixed arc runner 12, and the upper portion of the fixed contact 1 and the fixed arc runner are covered. 12 was connected. As a result, an eccentric magnetic flux is generated for the ignited arc, which strengthens the electromagnetic force in the direction of the fixed-side arc runner 12. By strengthening the driving force, the commutation time is shortened, and high breaking performance is obtained. be able to.

Embodiment 2.
In the first embodiment, the fixed-side arc runner 12 does not cover the back surface of the fixed contact 1, but in the second embodiment, the fixed-side arc runner 12 covers not only the side surface of the fixed contact 1 but also the back surface of the contact. shaped. The structure is the same as that of the DC circuit breaker of Embodiment 1 except that the fixed-side arc runner 12 covers the back surface of the contact. FIG. 6 is a cross-sectional view showing the fixed-side arc runner of the second embodiment. As shown in FIG. 6, since the fixed-side arc runner 12 covers the back surface of the contact, a high effect of improving the electromagnetic force can be obtained. Also, since the arc runner covering the back surface of the contact is arranged at a position that does not come into contact with the arc, it may be composed of a separate member from the fixed-side arc runner 12 .

Embodiment 3.
In Embodiment 3, the fixed contact base metal 2 is provided with the slit 23 . This structure increases the electromagnetic force due to the self-magnetic field. The structure of the DC circuit breaker is the same as that of the first and second embodiments except that slits 23 are provided.

FIG. 7 shows a side sectional view of the stationary arc runner 12 of this embodiment. A slit 23 is formed in parallel with the contact surface of the fixed contact 1 in the rear portion of the contact back of the fixed contact base metal 2 . Although FIG. 7 shows an example in which the slits 23 are formed in the stationary arc runner 12 of the second embodiment, slits may be formed in the stationary arc runner 12 of the first embodiment.

As in this structure, the slit 23 is formed in the portion of the fixed contact base metal 2 on the side of the fixed side arc runner 12 (in FIG. 7, the upper surface of the fixed contact base metal 2), so that the current path near the fixed contact 1 becomes a path 24 from below bypassing the slit 23, and the magnetic flux generated in the path 24 generates an electromagnetic force 25 in the direction of the fixed-side arc runner 12 for the arc 16 that is ignited between the contacts. This promotes arc elongation and shortens the commutation time.

The slits 23 provided in the fixed contact base metal 2 in the above structure are more effective the closer they are to the contact surface of the fixed contact 1, and the deeper the slits 23 are, the more effective they are. Further, it is desirable that the angle of the slit 23 is set in parallel with the contact surface of the fixed contact 1 because of high effect. However, even if it is changed to a predetermined angle other than that, an effect can be obtained. Furthermore, the position of the slit 23 may be determined in consideration of the mechanical strength that can withstand contact opening and closing and the limit value of temperature rise due to energization. good.

Also, a part of the fixed-side arc runner 12 described in

Embodiments

1 and 2 may be arranged behind the slit 23 to ensure strength. This structure not only provides higher strength, but also enhances the effect of the electromagnetic force by providing deep slits. In this structure, since the slit 23 is partially blocked by the fixed-side arc runner 12, a current path is generated that flows in the contact direction from above via the fixed-side arc runner 12. FIG. In this case, due to the difference in conductivity between copper, which is a member of the fixed contact base metal 2, and iron, which is a member of the fixed side arc runner 12, the current in the lower path passing through copper becomes dominant, so the electromagnetic force is significantly increased. Strength is ensured without deterioration.

Embodiment 4.
In the fourth embodiment, the ribs 26 are provided on the side surface of the stationary arc runner 12 . FIG. 8 is a perspective view showing the stator and fixed-side arc runners of this embodiment. As shown in FIG. 8, a rib 26 extending from the vicinity of the contact point to the terminal end is erected on the side surface of the stationary arc runner 12 . By adopting this structure, the commutation and running of the arc are promoted for a small current below the rated current value where the arc driving force is weak. The structure is the same as that of the DC circuit breakers of Embodiments 1 to 3 except that ribs 26 are provided.

　The arc in the small current range below the rated current is smaller than the large current, so the electromagnetic force due to the self-magnetic field and the biased magnetic flux is low. In addition, the electrical conductivity of the commutation destination space is difficult to increase because the contact points and arc runners are less likely to be ablated by the arc. For these reasons, the arc driving force is low, and commutation and running are difficult. On the other hand, in order to cut off the small current, a structure can be used in which an air puffer is provided to blow air from the lower part of the contact when the contact is opened, and the arc is forcibly driven toward the arc extinguishing chamber 15 to cut off the arc. However, the structure using the air puffer tends to increase the size of the device.

In this embodiment, taking advantage of the feature that the arc is easily ignited at the edge, a rib 26 is erected on the side surface of the fixed-side arc runner 12, and the rib 26 is provided to the end of the fixed-side arc runner 12. This structure not only improves commutation performance, but also improves running performance and promotes arc elongation to obtain a high arc voltage, thereby improving small current interruption performance. Even if this structure is provided in the arc runner 13 on the movable side, the same effect can be obtained. In addition, the DC circuit breaker of this embodiment can be made smaller and lighter than a DC circuit breaker using an air puffer.

In this structure, the rib 26 and the fixed side arc runner 12 are integrally formed by cutting, but they may be manufactured as separate members and fastened with bolts, rivets, or the like, or welded. Further, the ribs 26 may be formed not only by cutting, but also by sheet metal bending.

If the fixed side arc runner 12 and the rib 26 on the side are formed of separate members, the degree of contact between the part that connects them (for example, the screwed part when fixing by screwing) and the other part is different. Since the current flows intensively in the joints where the degree of contact is strong, depending on the formation position of the joints, the current passing through the joints gives the arc an electromagnetic force in the direction of the contact, causing the arc to flow back to the contact side. It may happen. On the other hand, if the rib 26 is integrally formed with the fixed side arc runner 12, the current flow will not concentrate on the joint position, and only the arc driving force in the direction of the arc extinguishing chamber 15 can be obtained. More preferably, the ribs 26 on the side surfaces of the side arc runner 12 are formed integrally with the fixed side arc runner 12 .

Embodiment 5.
In Embodiment 5, the fixed-side arc runner 12, the fixed contact 1, and the fixed contact base metal 2 are integrally constructed. 9 is a perspective view showing the stator and stationary arc runners of this embodiment, and FIG. 10 is a cross-sectional view of the stator and stationary arc runners of FIG. 9 taken along the line AA. It should be noted that the structure is the same as that of the DC circuit breaker of Embodiment 4, except that it has an integral structure. 9 and 10, the fixed contact 1, the fixed contact base metal 2 and the fixed arc runner 12 are integrally brazed, and then cutting 27 is performed from the upper end surface of the fixed contact 1 to the fixed arc runner 12. , the boundary between the upper end surface of the fixed contact 1 and the fixed side arc runner 12 is smoothly connected. By adopting this structure, at the boundary that is the joint between the fixed contact 1 and the fixed side arc runner 12 that occurs after brazing, the ignited small current arc is prevented from stagnation and agglutination, and the fixed side arc runner 12 can promote the commutation to and improve the breaking performance.

9 and 10, by forming an inclined portion 1c inclined toward the fixed-side arc runner 12 on the upper side of the contact surface of the fixed contact 1, the inclined portion 1c and the fixed contact 1 can be aligned, and the boundary between the inclined portion 1c of the fixed contact 1 and the fixed-side arc runner 12 can be smoothly connected by cutting.

In this structure, the joint between the contact and the arc runner is cut until it touches the upper end of the arc runner, but cutting only the upper surface of the contact and the vicinity of the joint surface of the lower part of the arc runner is also effective.

9 and 10 show an example applied to the DC circuit breaker of Embodiment 4, but the configuration of the integrated structure may be applied to the DC circuit breakers of Embodiments 1 to 3.

While this application describes various exemplary embodiments and examples, various features, aspects, and functions described in one or more embodiments may not apply to particular embodiments. can be applied to the embodiments singly or in various combinations.
Accordingly, numerous variations not illustrated are envisioned within the scope of the technology disclosed herein. For example, modification, addition or omission of at least one component, extraction of at least one component, and combination with components of other embodiments shall be included.

1: fixed contact, 2: fixed contact base metal, 3: stator, 4: movable contact, 5: movable contact base metal, 6: mover, 7: closing actuator, 8: upper conductor, 9: lower conductor, 10 : detector, 11: latch, 12: stationary arc runner, 13: movable arc runner, 14: grid, 15: arc extinguishing chamber, 16, 17, 18, 19: arc, 23: slit, 26: rib.

Claims

A stator having a fixed contact, a movable element having a movable contact that can be brought into contact with and separated from the fixed contact, and a movable element disposed near the fixed contact and the movable contact, and generated when the fixed contact and the movable contact are opened. A stationary arc runner for driving an arc into an arc-extinguishing chamber, wherein the stationary contact has an end face connected to the stationary arc runner and a side face adjacent to the end face, the end face and the side face of the stationary contact A direct-current circuit breaker, wherein the stationary-side arc runner is formed so as to cover the
The DC circuit breaker according to claim 1, wherein the fixed side arc runner is formed so as to cover the back surface of the fixed contact.
A slit is formed behind a connection portion of a fixed contact base metal that is connected to the fixed contact and constitutes the stator and is connected to the fixed contact, and the slit is formed on the fixed side arc runner side of the fixed contact base metal. 3. The direct current circuit breaker according to claim 1, wherein the direct current circuit breaker is formed at a portion.
The DC circuit breaker according to any one of claims 1 to 3, characterized in that ribs are formed on the side surface of the stationary arc runner.
The DC circuit breaker according to claim 4, wherein the ribs formed on the side surface of the stationary arc runner are formed integrally with the stationary arc runner.
The fixed-side arc runner, the fixed contact, and a fixed contact base metal that is connected to the fixed contact and constitutes the stator are integrally structured. 4. The DC circuit breaker according to any one of claims 1 to 3, characterized in that it has a slanted portion sloping at an angle, and a boundary between said fixed contact and said fixed-side arc runner has a smooth shape.
7. The fixed contact according to any one of claims 1 to 6, wherein the height of the contact contact surface of the fixed contact is the same as or higher than the portion covering the side surface of the fixed contact in the fixed side arc runner. A DC circuit breaker as described.