circuit breaker

Abstract

To provide a circuit breaker in which a device such as a distribution board to be housed can be reduced in size, and which has excellent operability.SOLUTION: A circuit breaker 10 includes: a stator 24 that is connected to a power supply side terminal 12; a plurality of grids 52 that extinguishes an arc A generated between the stator 24 and a movable element 26 at a current disconnection of the movable element 26 which is contacted and separated to / from the stator 24 so as to be connected to a load side terminal 14; an arc-extinguishing chamber 30 in which each grid 52 is housed; an exhaust port 50 that is formed in the arc-extinguishing chamber 30 and exhausts a hot gas G generated from the arc A; and a voltage induction 62 that is provided at a position where the hot gas G contacts in the arc-extinguishing chamber 30. The voltage induction 62 is connected to the load side terminal 14 via a resister 64. The voltage induction 62 is provided on a first wall 44 on a side opposite to a stator contact 24a of the stator 24 in the arc-extinguishing chamber 30.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a circuit breaker for connecting and disconnecting a circuit between terminals. [Background technology]

[0002] In a circuit breaker, the hot gas generated from the arc when current is interrupted contains ablated gas from the electrode material and the arc-extinguishing metal grid, making it conductive. In a circuit breaker, the conductive hot gas is exhausted to the outside through an exhaust port to prevent the internal pressure of the arc-extinguishing chamber from increasing.

[0003] Circuit breakers are sometimes placed inside switchboards. There is a concern that conductive hot gas exhausted from the circuit breaker could develop into a ground fault or short circuit if it comes into contact with the metal housing of the switchboard. In order to sufficiently cool the hot gas and allow it to disperse, a large arc space must be secured between the exhaust port and the switchboard housing, which hinders the miniaturization of the device.

[0004] For this reason, in the circuit breaker described in Patent Document 1, a labyrinth structure made of a resin material is placed outside the exhaust port, and the hot gas is lowered in temperature and conductivity inside this structure before being discharged into the external space. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-103005 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in many circuit breakers, the hot gas exhaust port is located near the terminal due to its configuration. Therefore, the labyrinth structure described in Patent Document 1 is also located near the terminal, making it difficult to attach and detach the electric wire to and from the terminal. Therefore, it is preferable to install the labyrinth structure after connecting the electric wire, but this increases the number of work steps. Furthermore, if the circuit breaker is three-phase, three labyrinth structures must also be installed.

[0007] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a circuit breaker that can be housed in a small device such as a distribution board and that is easy to work with. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the present invention provides a circuit breaker for connecting and breaking a circuit between one and another terminals, comprising: a stator connected to one terminal; an armature connected to the other terminal and adapted to move toward and away from the stator; a plurality of grids for extinguishing an arc generated between the stator and the armature when current is interrupted; an arc-extinguishing chamber housing the grids; an exhaust port formed in the arc-extinguishing chamber for discharging hot gas generated from the arc; and a voltage inductor made of a conductor or resistor, provided in the arc-extinguishing chamber at a location where the hot gas comes into contact with the voltage inductor, the voltage inductor being electrically connected to the other terminal. Such a circuit breaker allows for the miniaturization of a device, such as a switchboard, in which it is housed, and is easy to work with.

[0009] The voltage inductor may be provided on a first wall of the arc-extinguishing chamber on a side facing the fixed contact of the stator, thereby making it easier for hot gas to come into contact with the voltage inductor.

[0010] The arc extinguishing chamber may have a second wall provided on a side where the arc moves as it extends, the exhaust port may be provided in the vicinity of a corner of the second wall where the second wall meets the first wall, and a guide surface may be provided in the gap between the ends of the grids and the second wall, the guide surface being inclined to guide the hot gas away from the exhaust port toward the first wall, thereby making it easier to guide the hot gas to the voltage conductor.

[0011] The voltage conductor may be provided at least at a portion of the first wall that intersects with an extension of the guide surface, thereby ensuring that the hot gas comes into contact with the voltage conductor.

[0012] The voltage inductor may be connected to the other terminal via a resistor, which makes it difficult for the arc to be commutated to the voltage inductor. [Effects of the Invention]

[0013] In the circuit breaker according to the present invention, the voltage inductor is connected to the load terminal, so that the potential of the hot gas that comes into contact with the voltage inductor drops to the same voltage as or close to that of the load terminal. Even if the hot gas with a reduced potential comes into contact with a switchboard or other device after being exhausted from the exhaust port, there is no risk of a ground fault occurring. Arc space can be reduced, allowing for a more compact device. Furthermore, because this process essentially occurs inside the circuit breaker, no external additional elements are required for the exhaust port, and the workability of attaching and detaching the electric wire terminals is excellent. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of a circuit breaker according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of a circuit breaker. [Figure 3] FIG. 3 is a partially enlarged schematic cross-sectional view of the circuit breaker. [Figure 4] FIG. 4 is a cross-sectional side view of a circuit breaker and switchboard in an arcing situation. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a circuit breaker according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments.

[0016] FIG. 1 is a perspective view of a circuit breaker 10 according to an embodiment of the present invention. The circuit breaker 10 is a molded case circuit breaker, earth leakage circuit interrupter, or the like, and is installed between a power source and a load, automatically cutting off the circuit when it detects a large current flowing through the circuit. The circuit breaker 10 connects and cuts off current between a power source side terminal (one terminal) 12 and a load side terminal (the other terminal) 14. The circuit breaker 10 is for three-phase AC, but may also be for two-phase or direct current.

[0017] In this case, the circuit breaker 10 is for three-phase AC, and therefore is provided with three power supply terminals 12. Each power supply terminal 12 is provided inside a wire connection space 16, which is partitioned on both sides by walls 15. The wire connection space 16 is open in two directions: in the direction in which the wires extend and in the direction in which the connection screws are inserted. The load terminal 14 is located on the opposite side of the power supply terminal 12 and has a configuration similar to that of the power supply terminal 12. In the following explanation, for the purpose of identifying the orientation, the side on which the power supply terminal 12 is provided will also be referred to as the power supply side, and the side on which the load terminal 14 is provided will also be referred to as the load side. The up and down directions will be indicated by the arrows in each figure. These designations are used for convenience of explanation, and the installation orientation of the circuit breaker 10 is not limited.

[0018] Fig. 2 is a schematic cross-sectional view of the circuit breaker 10. Fig. 2 shows one of the three phases, but each phase has the same configuration. The circuit breaker 10 includes, within a main body 22, a stator 24 having fixed contacts 24a, and a mover 26 that moves relative to the stator 24 to move a movable contact 26a toward and away from the fixed contact 24a.

[0019] The stator 24 is a part of the power supply side plate 28 extending from the power supply side terminal 12. The power supply side terminal 12 is one end of the power supply side plate. The mover 26 is an arm-shaped member that rotates around an axis 26b. The movable contact 26a is located at the tip of the mover 26, facing the fixed contact 24a. As the mover 26 rotates, the movable contact 26a moves up and down inside the arc-extinguishing chamber 30, moving toward and away from the fixed contact 24a. In other words, when the mover 26 tilts down, the fixed contact 24a and the movable contact 26a come into contact with each other, closing the circuit breaker 10, and when the mover 26 rises up, the fixed contact 24a and the movable contact 26a separate, opening the circuit breaker 10 and interrupting the current. For example, the position of the mover 26 is approximately horizontal in FIG. 2 when closed, and approximately 30 degrees in FIG. 2 when open.

[0020] The shaft 26b of the mover 26 is journaled on a metal shaft seat 32. A small metal relay bracket 34 is connected to the shaft seat 32. The load side terminal 14 is one end of a load side plate 36. The relay bracket 34 is connected to the load side terminal 14 by the load side plate 36. In other words, the mover 26 is electrically connected to the load side terminal 14 via the shaft seat 32, relay bracket 34, and load side plate 36. In Figure 2, reference numeral 38 denotes an operating handle, reference numeral 40 denotes an opening / closing mechanism, and reference numeral 42 denotes a tripping device.

[0021] 3 is a partially enlarged schematic cross-sectional view of the circuit breaker 10. A fixed contact 24a is provided facing upward at the bottom of the arc-extinguishing chamber 30. A movable contact 26a moves up and down on the load side of the arc-extinguishing chamber 30.

[0022] The upper wall (opposing the fixed contact 24a) of the arc extinguishing chamber 30 is referred to as the first wall 44. In this case, the first wall 44 forms the upper wall of the housing of the circuit breaker 10. As will be described later, when current is interrupted, an arc A can occur between the fixed contact 24a and the movable contact 26a. The generated arc A moves while extending toward the power source due to the action of magnetic flux. The wall of the arc extinguishing chamber 30 on the side toward which the arc A moves is referred to as the second wall 46. In this case, the second wall 46 serves as a partition wall between the arc extinguishing chamber 30 and the electric wire connection space 16 (see FIG. 1). An exhaust port 50 is provided above the second wall 46 near a corner 48 where the second wall 46 meets the first wall 44. The exhaust port 50 connects the arc extinguishing chamber 30 to the external electric wire connection space 16. The end of the first wall 44 on the power source side forms an inclined surface 44a that faces the corner 48.

[0023] The arc extinguishing chamber 30 contains a large number of grids 52 for extinguishing the arc A. Each grid 52 is fixed to a pair of side plates 54 that form the inner wall of the arc extinguishing chamber 30. The grids 52 are plate-shaped except for the upper and lower grids, and are arranged substantially parallel to each other at narrow intervals in the vertical direction. The grids 52 are provided over almost the entire area of ​​the arc extinguishing chamber 30. The grids 52 are, for example, made of a magnetic material.

[0024] These grids 52 are set at approximately the same inclination as the mover 26 in the open-circuit state. The ends of these grids 52 on the power supply side are set so as to gradually become farther away from the second wall 46, from those arranged at the bottom to those arranged at the top. In other words, there are acute-angled gaps 56 between the second wall 46 and the ends of the multiple grids 52 that widen upward.

[0025] The uppermost grid 52a (referred to as upper grid 52a) of the multiple grids 52 has an end 52aa that is slightly closer to the load side than the others. The load-side end of the upper grid 52a forms a bent portion 52ab that points slightly upward. The bent portion 52ab avoids interference with the mover 26 and makes it easier for the arc A to hit it.

[0026] An inclined plate 60 is provided in the gap 56. The lower end of the inclined plate 60 is fixed to the second wall 46 and is gently inclined upward so as to move toward the load side. The inclined plate 60 is spaced at a substantially constant distance from the power supply side end of the grids 52 other than the upper grid 52a. The upper end of the inclined plate 60 is located slightly lower than the exhaust port 50. The inclined plate 60 is fixed to the second wall 46 and the side plate 54 and is stable. A solid structure may be formed between the inclined plate 60 and the second wall 46. In other words, the inclined plate 60 is only required to be configured so that a guide surface 60a, which is an inclined surface on the load side, is formed.

[0027] As shown in Figures 2 and 3, in the circuit breaker 10, a voltage inductor 62 is provided extending from the wall surface of the first wall 44 of the arc-extinguishing chamber 30 to the relay bracket 34. The circuit breaker 10 is a three-phase circuit breaker, and a voltage inductor 62 is provided for each phase. The voltage inductor 62 is, for example, formed by bending a metal plate along a path, and is stable within the circuit breaker 10. The voltage inductor 62 may be formed of a flexible wire extending to the relay bracket 34. Flexible wires facilitate routing during the assembly process. The voltage inductor 62 may be connected to the shaft seat 32 or the load-side plate 36 in addition to the relay bracket 34. In other words, the voltage inductor 62 may be electrically connected to the load-side terminal 14. Although the voltage inductor 62 is electrically connected to the load-side terminal 14 even when connected to the armature 26, it is preferable to connect it to the shaft seat 32, relay bracket 34, or load-side plate 36, which are fixed and do not move.

[0028] The voltage inductor 62 is connected to the relay bracket 34 via a resistor 64. Conceptually, the resistor 64 can be considered as part of the voltage inductor 62. The resistor 64 may be provided anywhere along the voltage inductor 62. Figure 2 shows an example in which one end of the resistor 64 is connected to the relay bracket 34.

[0029] Next, a description will be given of the operation of the circuit breaker 10. Figure 4 is a cross-sectional side view of the circuit breaker 10 and the switchboard 66 in a situation where an arc A has occurred.

[0030] As shown in Fig. 4, the circuit breaker 10 may be installed inside a switchboard 66 having a metal housing. In the circuit breaker 10, an arc A may occur between the stator 24 and the armature 26 during a current interruption operation. The arc A is driven by the magnetic flux toward the depth of the notch in the grid 52, where it is divided and cooled by the grid 52, increasing the arc resistance. As a result, the power supply voltage is no longer able to maintain the arc voltage, and the arc A is extinguished.

[0031] Hot gas G is generated during the process in which arc A is extended and extinguished by grid 52. In Fig. 4, the area of ​​hot gas G is conceptually indicated by a dotted background. Pressure rises within arc extinguishing chamber 30 due to gas overheating caused by arc A, and hot gas G generated within arc extinguishing chamber 30 forms a gas flow and is discharged to the outside through exhaust port 50. Hot gas G is conductive because it contains metallic vapor.

[0032] Incidentally, the hot gas G generated in a circuit breaker according to the prior art has a potential that corresponds to the distance to the stator 24 and the mover 26. This potential can be, for example, about halfway between the power supply side potential and the load side potential, and can be sufficiently high. There is a concern that a ground fault may occur if the high-potential hot gas G comes into contact with the housing of the switchboard 66 after being discharged from the exhaust port 50. For this reason, it is necessary to secure an arc space between the circuit breaker and the housing, which has hindered the miniaturization of the device.

[0033] In contrast, in the circuit breaker 10 according to this embodiment, the voltage inductor 62 is provided on the first wall 44 inside the arc extinguishing chamber 30, and the hot gas G comes into contact with the voltage inductor 62. The voltage inductor 62 is made of a conductor and a resistor, and therefore has the effect of inducing a voltage, and the potential of the hot gas G that comes into contact with the voltage inductor 62 drops. Because the voltage inductor 62 is connected to the load-side terminal 14, the potential of the hot gas G drops to the same voltage as or close to that of the load-side terminal 14. Even if the hot gas G with a reduced potential comes into contact with the switchboard 66 after being discharged from the exhaust port 50, there is no concern of a ground fault occurring, and the arc space can be reduced, allowing for a more compact device.

[0034] Hot gas G is generally considered to be generated in the same location as arc A. Arc A, at least initially, is generated between fixed contact 24a and movable contact 26a. Voltage inductor 62 has the function of bringing the potential of hot gas G closer to the potential of load-side terminal 14 and movable contact 26. Therefore, providing voltage inductor 62 on first wall 44, which faces fixed contact 24a, effectively induces voltage. Furthermore, first wall 44 is the wall farthest from stator 24 within arc-extinguishing chamber 30, and arc A is not commutated to voltage inductor 62 provided on first wall 44. Furthermore, compared to other walls within arc-extinguishing chamber 30, first wall 44 facilitates layout design of voltage inductor 62 relative to relay bracket 34 and shaft seat 32.

[0035] Furthermore, in the circuit breaker 10, the potential of the generated hot gas G is appropriately reduced by the time it is discharged from the exhaust port 50, so there is no need to provide a structure such as that described in Patent Document 1 at the exhaust port 50. This widens the electric wire connection space 16, exposing the power supply side terminals 12 and improving the workability of attaching and detaching the electric wire terminals. However, depending on the conditions, it is also possible to provide the circuit breaker 10 with a structure such as that described in Patent Document 1 in order to further suppress the voltage of the hot gas G.

[0036] Furthermore, although the voltage inductor 62 is basically a conductor such as a metal plate, it is connected to the load terminal 14 via the resistor 64, and therefore its resistance is at least greater than that of the mover 26 when viewed from the load terminal 14, and the arc A generated between the stator 24 and the mover 26 does not commutate between the stator 24 and the voltage inductor 62. The resistor 64 should have an appropriate capacity selected based on the current expected to flow when the potential of the hot gas G is reduced and the duration of current flow.

[0037] Furthermore, if the voltage inductor 62 is made of a resistive material such as carbon or a resin plate containing carbon, the same effect can be obtained even if the resistor 64 is omitted. Furthermore, if it is confirmed by taking into consideration the distance between the voltage inductor 62 and the stator 24, the arrangement of the grid 52 between the voltage inductor 62 and the stator 24, or by conducting experiments, that the arc A will not be commutated from the stator 24 to the voltage inductor 62 via the hot gas G, the resistor 64 may be omitted even if the voltage inductor 62 is a conductor.

[0038] As shown in FIG. 3 , hot gas G moves toward the power source through the gaps between the grids 52, eventually joining together and being discharged through the exhaust port 50. Because each grid 52 is inclined upward toward the power source and the exhaust port 50 is located near the upper end of the second wall 46, hot gas G flows diagonally upward toward the corner 48. Therefore, hot gas G is likely to come into contact with the voltage conductor 62 provided on the first wall 44, particularly near the corner 48. Because hot gas G mainly flows out from between the grids 52, the voltage conductor 62 within the arc extinguishing chamber 30 is preferably provided on the first wall 44 in a range extending from the end 52aa of the upper grid 52a to the corner 48 in the horizontal direction. This allows hot gas G to easily come into contact with the voltage conductor 62.

[0039] As described above, acute-angled gaps 56 that widen upward exist between the second wall 46 and the ends of the plurality of grids 52, but because the inclined plates 60 are provided in the gaps 56, the hot gas G that flows out from the gaps between the grids 52 is guided upward along the guide surfaces 60a. Therefore, the portion of the hot gas G that is generated relatively low within the arc extinguishing chamber 30 does not rise vertically along the second wall 46, but is guided upward by the guide surfaces 60a and guided slightly toward the load side so as to move away from the exhaust port 50.

[0040] Therefore, the hot gas G is not discharged directly from the exhaust port 50, but instead detours around the first wall 44 before flowing to the exhaust port 50, making it easier for the hot gas G to come into contact with the voltage inductor 62. In other words, the guide surface 60a is set to be inclined toward the first wall 44 so as to move the hot gas G away from the exhaust port 50, making it easier for the hot gas G to come into contact with the voltage inductor 62 of the first wall 44.

[0041] Furthermore, the voltage conductor 62 is preferably provided at least at a location on the first wall 44 that intersects with an imaginary extension surface 60ax ​​of the guide surface 60a. This ensures that the hot gas G guided by the guide surface 60a comes into contact with the voltage conductor 62.

[0042] However, the flow path of the hot gas G may change due to various influences such as the shape of the arc extinguishing chamber 30, the position of the exhaust port 50, and the arrangement of the grid 52. Therefore, the voltage inductor 62 is not limited to the above example, and may be provided at a location where the hot gas G comes into contact with the hot gas G according to the flow of the hot gas G.

[0043] The present invention is not limited to the above-described embodiment, and can of course be freely modified within the scope of the gist of the present invention. [Explanation of symbols]

[0044] 10. Circuit Breaker 12 Power supply terminal (one terminal) 14 Load side terminal (other terminal) 24 Stator 24a fixed contact 26 Mover 26a Movable contact 28 Power supply side plate 30 Arc room 36 Load side plate 44 1st wall 46 Second wall 48 Corner 50 exhaust port 52 Grid 52a Top Grid 52aa end 56 Gap 60 Inclined plate 60a Guide surface 60ax extension surface 62 Voltage Inductor 64 Resistor 66 Switchboard A Arc G Hot Gas

Claims

1. A circuit breaker for connecting and disconnecting a circuit between one and the other terminals, a stator connected to one terminal; a mover connected to the other terminal and adapted to move toward and away from the stator; a plurality of grids for extinguishing arcs that occur between the stator and the movable element when current is interrupted; an arc extinguishing chamber in which the grid is housed; an exhaust port formed in the arc extinguishing chamber for discharging hot gas generated from the arc; a voltage inductor provided in the arc extinguishing chamber at a location where the hot gas comes into contact, the voltage inductor being made of a conductor or a resistor; and the voltage inductor is provided on a first wall of the arc extinguishing chamber on a side facing the fixed contact of the stator, and is electrically connected to the other terminal; the arc extinguishing chamber has a second wall provided on a side to which the arc moves when it extends, the exhaust port is provided in the second wall near a corner where the second wall meets the first wall, In the gaps between the ends of the grids and the second wall, guide surfaces are provided that are inclined toward the first wall so as to move the hot gas away from the exhaust port. A circuit breaker characterized by:

2. The voltage inductor is provided at least at a portion of the first wall that intersects with an extension of the guide surface.

2. The circuit breaker of claim 1.

3. The voltage inductor is connected to the other terminal via a resistor.

3. The circuit breaker according to claim 1 or 2.

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