JP2014192025A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit breaker capable of guiding an arc occurring between contacts so as to move away from the contacts quickly.SOLUTION: The circuit breaker includes: a fixed contact plate 42 and an arc running plate 70 which guide an arc A1 occurring between contacts so as to move away from the contacts by the action of an electromagnetic field; and a magnetic substance 8 which is disposed in the vicinity of the fixed contact plate 42 and the arc running plate 70 and is electrically isolated from the fixed contact plate 42 and the arc running plate 70. The magnetic substance 8 is disposed so that a magnetic field generated around the fixed contact plate 42 and the arc running plate 70 passes through the magnetic substance.

Description

  The present invention relates to a circuit breaker.

  Conventionally, there has been known a circuit breaker having a link mechanism that opens and closes a contact according to a handle operation, and a trip mechanism that drives a link mechanism and forcibly opens a contact when an abnormal current flowing in an electric circuit is detected. For example, it is disclosed in Patent Document 1. The circuit breaker described in Patent Document 1 includes an arc extinguishing device for quickly extinguishing an arc generated when a contact is opened.

  The arc extinguishing device includes an arc traveling plate and an arc extinguishing grid. The arc traveling plate is formed of a strip-shaped metal plate and guides the generated arc to the arc extinguishing grid. The arc extinguishing grid is configured by arranging a plurality of arc extinguishing plates in parallel along the thickness direction at a predetermined interval. The arc extinguishing grid breaks the induced arc. With this arc extinguishing device, when the movable contact leaves the fixed contact and an arc is generated, the arc is extended to extinguish the arc.

JP 2009-212063 A

  By the way, in the circuit breaker like the above-mentioned conventional example, the arc generated between the contacts is guided to the arc extinguishing grid by utilizing the Lorentz force acting on the arc. Here, in a circuit breaker that cuts off a large current, it is necessary to quickly extinguish the arc generated between the contacts, and therefore it is desirable to induce the arc to the arc extinguishing grid quickly. In addition, even in a circuit breaker that does not include an arc extinguishing grid, it is expected to guide the arc so that it is quickly moved away from the contact point.

  In order to induce the arc to move away from the contact point quickly, it is conceivable to increase the Lorentz force acting on the arc. As a means for increasing the Lorentz force, for example, a fixed contact plate to which the fixed contact is fixed may be formed of a magnetic material such as iron. However, a circuit breaker that cuts off a large current has a problem in that it is difficult to adopt such a configuration because the resistance in the current path through which the current flows must be reduced.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a circuit breaker capable of guiding an arc generated between contacts so as to be quickly moved away from the contacts.

  The circuit breaker of the present invention includes an induction member that induces an arc generated between contacts in a direction away from the contact by the action of an electromagnetic field, and a magnetic body that is disposed in the vicinity of the induction member and is electrically insulated from the induction member The magnetic body is arranged so that a magnetic field generated around the induction member passes therethrough.

  In this circuit breaker, it is preferable that the magnetic body is configured to cover at least a part of the surface of the induction member excluding the surface on which the arc travels.

  In this circuit breaker, the magnetic body is preferably arranged so that a magnetic field generated around the arc passes therethrough.

  The circuit breaker includes a body that houses the induction member, and the body is configured by coupling a plurality of members to each other by an assembly screw, and the assembly screw is a magnetic field generated around the induction member. Are preferably arranged so as to pass through and formed of a magnetic material.

  In the present invention, the magnetic body is arranged so that a magnetic field generated around the induction member passes. Therefore, according to the present invention, the Lorentz force acting on the arc generated between the contacts can be increased, and the arc can be induced to be quickly moved away from the contacts.

It is a figure which shows the model of the fixed contact board and arc travel board in the circuit breaker which concerns on embodiment of this invention, (a) is a perspective view, (b), (c) is a perspective view when arrange | positioning a magnetic body. It is. It is a figure which shows the basic composition of a circuit breaker same as the above, (a) is a side view, (b) is a perspective view. (A)-(d) is a figure which shows the external appearance of a circuit breaker same as the above. It is a figure explaining the induction | guidance | derivation to the arc-extinguishing apparatus in the circuit breaker same as the above. It is a figure explaining the magnetic field which generate | occur | produces with the arc current in a circuit breaker same as the above. (A), (b) is a figure explaining the Lorentz force which acts on the arc in a circuit breaker same as the above. It is a figure explaining the result of an electromagnetic field analysis in a circuit breaker same as the above, (a) is a basic model figure, (b) is a figure which shows a magnetic field at the time of forming a fixed contact plate with copper, (b) is fixed It is a figure which shows the magnetic field at the time of forming a contact plate with iron. It is a figure explaining the result of electromagnetic field analysis in a circuit breaker same as the above, (a) is a figure at the time of arranging the 1st magnetic body, (b) is a figure showing the magnetic field in (a), (c) is It is a figure at the time of arrange | positioning a 2nd magnetic body and a 3rd magnetic body, (d) is a figure which shows the magnetic field in (c). (A)-(c) is a figure at the time of arrange | positioning a 4th magnetic body and a 5th magnetic body in the circuit breaker same as the above.

  Hereinafter, in describing the circuit breaker according to the embodiment of the present invention, the basic configuration of the circuit breaker will be described with reference to the drawings. As shown in FIGS. 2 (a) and 2 (b), the circuit breaker includes a body 1, a first terminal portion 2, a second terminal portion 3, a contact portion 4, a link mechanism 5, and a trip mechanism. 6 and an arc extinguishing device 7. 2A and 2B show a state in which a cover 11 described later is removed. 2A and 2B show a state where the contact portion 4 is open.

  As shown in FIGS. 3A to 3D, the container body 1 is configured by butting the body 10 and the cover 11 together. Each of the body 10 and the cover 11 is formed in a box shape having one surface opened in the width direction (the left-right direction in FIG. 3B) by an insulating synthetic resin. Inside the container 1, the terminal portions 2 and 3, the contact portion 4, the link mechanism 5, the trip mechanism 6, and the arc extinguishing device 7 are accommodated.

  The 1st terminal part 2 is provided in the left end in Fig.2 (a) of the container 1, and the electric wire (not shown) for connecting with a load (not shown) is connected. The 2nd terminal part 3 is provided in the right end in Fig.2 (a) of the container 1, and the electric wire (not shown) for connecting with an external power supply (not shown) is connected. As shown in FIGS. 2A and 2B, the terminal portions 2 and 3 include terminal fittings 20 and 30 and terminal screws 21 and 31, respectively. Each of the terminal fittings 20 and 30 is a so-called pillar terminal that is formed in a rectangular tube shape having an axial direction in the left-right direction using a conductive metal plate. By inserting one end of the electric wire into the terminal fittings 20 and 30 and fastening the terminal screws 21 and 31, the electric wire can be connected to the terminal portions 2 and 3.

  As shown in FIGS. 2A and 2B, the contact portion 4 includes a fixed contact 40 and a movable contact 41 that contacts and separates from the fixed contact 40. The fixed contact 40 is fixed to the fixed contact plate 42. The fixed contact plate 42 is formed of a low resistance material such as copper, for example, and is curved in a cross-sectional view so as to cover one of the assembly screws 12 used when the body 10 and the cover 11 are coupled (FIG. 2). (See (a)). The movable contact 41 is provided at one end of an arm 43 formed by punching and bending a metal plate. The arm 43 is rotatable between a position where the movable contact 41 is in contact with the fixed contact 40 and a position where the arm 43 is separated from the fixed contact 40 with a shaft 43A provided at the other end as a fulcrum. One end of the first braided wire 44 is fixed to an intermediate portion of the arm 43. The other end of the first braided wire 44 is fixed to an intermediate portion of a bimetal plate 610 described later.

  The link mechanism 5 opens and closes the contact portion 4 in accordance with an opening / closing operation (on / off operation). The structure of such a link mechanism 5 is well known, but will be briefly described below. As shown in FIGS. 2A and 2B, the link mechanism 5 includes a handle 50 and a plurality of link members 51. The handle 50 is rotatably supported by the body 2 in a state where the operation knob 50A protrudes outside from a window hole 2A provided on the front wall of the body 2. Each link member 51 connects the handle 50 and the arm 43, and interlocks the arm 43 with the rotation operation of the handle 50. The handle 50 is rotatable between an on position where the contact portion 4 is closed and an off position where the contact portion 4 is opened.

  When detecting an abnormal current (short circuit current and overload current), the trip mechanism 6 drives the link mechanism 5 to forcibly open (that is, trip) the contact portion 4. The configuration of the trip mechanism 6 is well known, but will be briefly described below. As shown in FIGS. 2A and 2B, the trip mechanism 6 includes an electromagnetic trip device 60 and a thermal trip device 61.

  As shown in FIGS. 2A and 2B, the electromagnetic trip device 60 includes a coil 60A, a fixed iron core (not shown), a movable iron core (not shown), and a return spring (not shown). And a pin 60B and a yoke 60C. The coil 60A is formed by winding a rectangular copper wire around the outer peripheral surface of a coil bobbin 60D formed in a cylindrical shape from an insulating synthetic resin. One end of the coil 60 </ b> A is connected to the terminal fitting 20 of the first terminal portion 2, and the other end is connected to the fixed contact plate 42. The fixed iron core is made of a magnetic material and is housed inside the coil bobbin 60D. The movable iron core is made of a magnetic material and is slidably arranged between a position in contact with the fixed iron core and a position away from the fixed iron core in the coil bobbin 60D. The return spring is made of, for example, a coil spring, and is housed between the movable iron core and the fixed iron core in the coil bobbin 60D. The return spring bends when the movable iron core moves in a direction in contact with the fixed iron core, and generates an elastic force that moves the movable iron core in a direction away from the fixed iron core. The pin 60B is coupled to the movable iron core, and its tip protrudes outside the coil bobbin 60D. And the pin 60B is comprised so that the front-end | tip may cooperate with a part of link member 51, when a movable iron core is attracted | sucked by a fixed iron core. The yoke 60C is made of a magnetic material, and is formed so as to be curved in a sectional view so as to cover the periphery of the coil bobbin 60D as shown in FIG.

  The thermal tripping device 61 is composed of a bimetal plate 610 as shown in FIGS. As the bimetal plate 610, a direct heating type that curves by self-heating, or an indirectly heated type that curves by heating by a heater can be used. One end of the bimetal plate 610 is configured to cooperate with a part of the link member 51 when the bimetal plate 610 is curved. One end of the second braided wire 45 is fixed to the other end of the bimetal plate 610. The other end of the second braided wire 45 is connected to the terminal fitting 30 of the second terminal portion 3.

  The arc extinguishing device 7 is intended to quickly extinguish an arc A1 (see FIG. 4) generated when the contact portion 4 is opened. The arc extinguishing device 7 includes an arc traveling plate 70 and an arc extinguishing grid 71 as shown in FIGS. The arc traveling plate 70 is formed by bending a strip-shaped metal plate, and one end on the right side in FIG. 2A is coupled to one end of the bimetal plate 610. The arc traveling plate 70 extends to the left side of the container body 1 in FIG. 2A along the lower wall in the container body 1 in FIG. The arc extinguishing grid 71 includes a plurality of (12 in the drawing) arc extinguishing plates 710 and two (1 in the drawing) support plates 711. Each arc-extinguishing plate 710 is formed of a conductive material, and is arranged in parallel along the height direction of the vessel 1 (the vertical direction in FIG. 2A). Each support plate 711 is formed of an insulating material and covers both sides of each arc-extinguishing plate 710 in the width direction (direction perpendicular to the paper surface in FIG. 2A).

  Hereinafter, the operation of the arc extinguishing device 7 will be briefly described with reference to FIG. When the arc A1 is generated when the movable contact 41 is separated from the fixed contact 40, an arc current flows to the fixed contact plate 42 and the arc traveling plate 70 via the arc A1, and a magnetic field is generated by this current. By this magnetic field, a Lorentz force acts on the arc A1, and the arc A1 is extended and is induced to the left side in FIG. The arc extinguishing grid 71 divides the induced arc A <b> 1 by a plurality of arc extinguishing plates 710. Thereby, since a high arc voltage arises, it can suppress and suppress a short circuit current. That is, the fixed contact plate 42 and the arc traveling plate 70 correspond to “induction members” that guide the arc generated between the contacts in a direction away from the contact by the action of an electromagnetic field.

  Hereinafter, the operation of the link mechanism 5 will be briefly described. When the handle 50 is rotated to the on position, each link member 51 cooperates with the handle 50. As a result, the arm 43 rotates clockwise around the shaft 43A, and the movable contact 41 comes into contact with the fixed contact 40 (that is, the contact portion 4 is closed). As a result, the electric path is routed through the path of the terminal fitting 20, the coil 60A, the fixed contact plate 42, the fixed contact 40, the movable contact 41, the arm 43, the first braided wire 44, the bimetal plate 610, the second braided wire 45, and the terminal fitting 30. Formed and energized. At this time, the movable contact 41 is pressed in a direction toward the fixed contact 40 by an elastic force of a contact pressure spring (not shown). Thereby, the contact pressure with respect to the fixed contact 40 of the movable contact 41 is large.

  Thereafter, when the handle 50 is rotated to the off position, each link member 51 cooperates with the handle 50. As a result, the arm 43 rotates counterclockwise about the shaft 43A, and the movable contact 41 is separated from the fixed contact 40 (that is, the contact portion 4 is opened). Thereby, the electric circuit formed between each terminal part 2 and 3 is open | released, and electricity supply is cancelled | released.

  Next, the operation of the trip mechanism 6 will be briefly described. First, the operation of the electromagnetic trip device 60 will be described. In a state where no current flows through the coil 60A (initial state), the movable iron core is separated from the fixed iron core by the elastic force of the return spring. For this reason, the pin 60 </ b> B connected to the movable iron core is retracted to a position where it does not cooperate with a part of the link member 51.

  When a current flows between the terminal portions 2 and 3 and the coil 60A is energized, an attractive force is generated between the movable iron core and the fixed iron core so as to reduce the magnetic resistance of the magnetic path passing through the fixed iron core, the yoke 60C, and the movable iron core. Works. When the current flowing through the coil 60A is an excessive current such as a short circuit current, the movable iron core moves to the fixed iron core against the elastic force of the return spring. At this time, the pin 60B connected to the movable iron core projects rightward in FIG. 2A, and the tip of the pin 60B cooperates with a part of the link member 51, whereby the trip operation by the link mechanism 5 is performed. When the trip operation is performed and the contact portion 4 is forcibly opened, the current flowing through the coil 60A is reduced and the attractive force acting on the movable iron core is reduced. Then, the movable iron core is moved to the initial position by the elastic force of the return spring, and the pin 60B is also retracted to the initial position.

  Next, the operation of the thermal tripping device 61 will be described. In a state where no current flows through the bimetal plate 610 (initial state), the bimetal plate 610 is not curved and the bimetal plate 610 does not cooperate with a part of the link member 51. On the other hand, when an excessive current such as an overload current flows between the terminal portions 2 and 3, the temperature of the bimetal plate 610 rises due to the excessive current, and the bimetal plate 610 is bent. Thereby, the bimetal plate 610 cooperates with a part of the link member 51, and the trip operation by the link mechanism 5 is performed. When the trip operation is performed and the contact portion 4 is forcibly opened, the current flowing through the bimetal plate 610 decreases. Then, the temperature of the bimetal plate 610 decreases, the degree of curvature thereof decreases, and the bimetal plate 610 eventually returns to the initial state where it does not cooperate with part of the link member 51.

  Hereinafter, the principle that the arc A1 generated between the contacts is guided to the arc extinguishing grid 71 will be briefly described. In the following description, as shown in FIG. 5, it is assumed that the fixed contact plate 42 and the arc traveling plate 70 are both long flat plates and are arranged in parallel to each other. Further, it is assumed that the arc A1 is cylindrical as shown in FIG.

  When the arc A1 is generated between the contacts, the fixed contact plate 42 and the arc traveling plate 70 are short-circuited by the arc A1, as shown in FIG. The arc current I1 flows through the fixed contact plate 42, the arc A1, and the arc traveling plate 70. Due to the arc current I1, a magnetic field B1 along the circumferential direction of the arc current I1 is generated on the fixed contact plate 42. Similarly, a magnetic field B2 along the circumferential direction of the arc current I1 is generated in the arc A1, and a magnetic field B3 along the circumferential direction of the arc current I1 is generated on the arc traveling plate 70.

  As shown by the arrows in FIGS. 6A and 6B, the Lorentz force toward the center of the arc A1 acts on the arc A1. In FIGS. 6A and 6B, the thicker the arrow, the greater the Lorentz force, and the thinner the arrow, the smaller the Lorentz force. The Lorentz force acting on the arc A1 is determined by the length of the current path of the arc A1, the arc current I1, and the magnetic flux density interlinking with the arc current I1.

  In the first region on the right side of the arc A1 shown in FIG. 6B, the second region on the left side shown in FIG. 6B is generated by the magnetic fields B1 and B3 generated in the fixed contact plate 42 and the arc traveling plate 70, respectively. Compared to the region, the magnetic flux density interlinking with the arc current I1 is increased. Therefore, as shown in FIG. 6A, the left-handed first Lorentz force F1 in FIG. 6 is larger than the right-handed second Lorentz force F2 in FIG. The third Lorentz force F3 is applied. The arc A1 is guided to the arc extinguishing grid 71 by the third Lorentz force F3.

  In order to quickly guide the arc A1 to the arc extinguishing grid 71, the third Lorentz force F3 may be increased. And in order to enlarge the 3rd Lorentz force F3, what is necessary is just to enlarge the magnetic flux density linked with the arc current I1 in a 1st area | region. Therefore, in the circuit breaker according to the present embodiment, as shown in FIGS. 1B and 1C, the magnetic body 8 that is electrically insulated from the fixed contact plate 42 is disposed in the vicinity of the fixed contact plate 42. ing. Similarly, a magnetic body 8 that is electrically insulated from the arc traveling plate 70 is disposed in the vicinity of the arc traveling plate 70.

  Hereinafter, a model of the fixed contact plate 42 and the arc traveling plate 70 and a model of the magnetic body 8 are created, and it is assumed that an arc A1 is generated between the fixed contact plate 42 and the arc traveling plate 70. The results of electromagnetic field analysis using the method are shown. First, a basic model will be described. As shown in FIGS. 1A and 7A, the fixed contact plate 42 and the arc traveling plate 70 are both designed to be long flat plates. Each of the plates 42 and 70 is designed so that the width W1 is 4 mm, the thickness T1 is 1.5 mm, and the length L1 in the longitudinal direction is 45 mm. Further, it is assumed that an arc A1 having a diameter φ0 of 3 mm and a height L0 of 16 mm is generated between the fixed contact plate 42 and the arc traveling plate 70. Furthermore, it is assumed that an arc current I1 of 4 kA flows through each of the plates 42 and 70 and the arc A1.

  First, in the model shown in FIG. 1A, when the fixed contact plate 42 and the arc running plate 70 are designed with copper which is a nonmagnetic material, the periphery of each plate 42, 70 is shown in FIG. 7B. Magnetic fields B1 and B3 are generated. In FIG. 7B, only the magnetic field B1 generated around the fixed contact plate 42 is shown, and the same applies to FIGS. 7C, 8B, and 8D. . In the same figure, the thicker the arrow, the stronger the magnetic field B1, and the thinner the arrow, the weaker the magnetic field B1. The same applies to FIGS. 7 (c), 8 (b), and 8 (d). . In this case, the third Lorentz force F3 is 7.88N. In the following description, the model shown in FIG. 1A in which the plates 42 and 70 are designed with copper is referred to as a “basic model”.

  Here, as a reference, in the model shown in FIG. 1A, the analysis results when the fixed contact plate 42 and the arc traveling plate 70 are designed with iron (here, SPCC (cold rolled steel plate)) that is a magnetic material. Indicates. Magnetic fields B1 and B3 shown in FIG. 7C are generated around the plates 42 and 70, respectively. In this case, compared with the case where each plate 42 and 70 is designed with copper, magnetic field B1 and B3 which generate | occur | produce around each plate 42 and 70 becomes strong, and the magnetic flux density linked with the arc electric current I1 in a 1st area | region. Also grows. Therefore, the third Lorentz force F3 in this case is 9.126 N, which is 15.8% larger than the basic model.

  Next, a model in which the first magnetic body 80 is disposed as the magnetic body 8 will be described. The first magnetic body 80 is made of iron (here, SPCC (cold rolled steel plate)), which is a magnetic material, and is designed as a long flat plate as shown in FIG. As shown in FIGS. 1B and 8A, the first magnetic body 80 is designed so that the width W2 is 7 mm, the thickness T2 is 1 mm, and the length L2 in the longitudinal direction is 45 mm. As shown in FIG. 8A, the first magnetic body 80 is arranged with a certain distance G1 (= 0.5 mm) from the upper surface of the fixed contact plate 42 in the figure. Similarly, the first magnetic body 80 is arranged at a certain distance G1 from the lower surface of the arc traveling plate 70 in the figure. Therefore, the first magnetic body 80 is electrically insulated from both the fixed contact plate 42 and the arc traveling plate 70.

  In the model shown in FIG. 1B, when the fixed contact plate 42 and the arc traveling plate 70 are designed with copper, magnetic fields B1 and B3 shown in FIG. 8B are generated around the plates 42 and 70, respectively. . In this model, when the magnetic fields B1 and B3 pass through the first magnetic body 80, the magnetic fields B1 and B3 become stronger. For this reason, as a result, the magnetic flux density interlinking with the arc current I1 in the first region also increases. Therefore, the third Lorentz force F3 in this case is 9.694 N, which is 23.0% larger than the basic model.

  Here, as a reference, in the model shown in FIG. 1B, the analysis result when the fixed contact plate 42 and the arc traveling plate 70 are designed with iron (here, SPCC (cold rolled steel plate)) which is a magnetic material. Indicates. In this case, compared with the basic model, the magnetic fields B1 and B3 generated around the plates 42 and 70 become stronger, and the magnetic flux density interlinked with the arc current I1 in the first region also becomes larger. Therefore, the third Lorentz force F3 in this case is 10.278 N, which is 30.4% larger than the basic model.

  Next, a model in which the first magnetic body 80, the second magnetic body 81, and the third magnetic body 82 are arranged as the magnetic body 8 will be described. Each of the second magnetic body 81 and the third magnetic body 82 is made of iron (here, SPCC (cold rolled steel plate)), which is a magnetic material, and as shown in FIG. To design. As shown in FIGS. 1C and 8C, each of the magnetic bodies 81 and 82 is designed so that the width W3 is 3 mm, the thickness T3 is 1 mm, and the length L3 in the longitudinal direction is 45 mm. . As shown in FIG. 8C, the second magnetic body 81 is arranged with a fixed gap G2 (= 0.5 mm) from the left surface of the fixed contact plate 42 and the arc traveling plate 70 in the figure. As shown in FIG. 8C, the third magnetic body 82 is disposed with a fixed gap G2 from the right surface of the fixed contact plate 42 and the arc traveling plate 70 in the figure. Accordingly, the magnetic bodies 81 and 82 are electrically insulated from both the fixed contact plate 42 and the arc traveling plate 70.

  In the model shown in FIG. 1C, when the fixed contact plate 42 and the arc traveling plate 70 are designed with copper, magnetic fields B1 and B3 shown in FIG. 8D are generated around the plates 42 and 70, respectively. . In this model, the magnetic fields B1 and B3 pass through not only the first magnetic body 80 but also the second magnetic body 81 and the third magnetic body 82, so that the magnetic fields B1 and B3 are compared with the model shown in FIG. Becomes even stronger. For this reason, as a result, the magnetic flux density interlinking with the arc current I1 in the first region is further increased compared to the model shown in FIG. Therefore, the third Lorentz force F3 in this case is 12.718 N, which is 61.4% larger than the basic model.

  As described above, in the circuit breaker according to the present embodiment, the magnetic body 8 is arranged so that the magnetic fields B1 and B3 generated around the fixed contact plate 42 and the arc traveling plate 70 that are induction members pass. For this reason, in the circuit breaker of the present embodiment, the Lorentz force (third Lorentz force F3) acting on the arc A1 can be increased, and the arc A1 generated between the contacts can be quickly guided to the arc extinguishing grid 71. Can do. In other words, the circuit breaker of the present embodiment can guide the arc A1 generated between the contacts so as to be quickly away from the contacts.

  In particular, as shown in FIG. 1C, if the magnetic body 8 is arranged so as to cover the periphery of the fixed contact plate 42 and the arc traveling plate 70, the Lorentz force acting on the arc A1 can be further increased and more quickly. The arc A1 can be guided to the arc extinguishing grid 71. As shown in FIG. 8C, the arc A1 travels on the lower surface of the fixed contact plate 42 in FIG. 8 and the upper surface of the arc traveling plate 70 in FIG. For this reason, it is desirable to arrange the magnetic body 8 so as to cover at least a part of the surface excluding the surface on which the arc A1 travels among the surfaces of the plates 42 and 70.

  By the way, as shown in FIGS. 9A to 9C, the fourth magnetic body is formed on both sides of the fixed contact plate 42 and the arc traveling plate 70 along the short direction (left and right direction in FIG. 8A). 83 and the fifth magnetic body 84 may be disposed. The fourth magnetic body 83 and the fifth magnetic body 84 are both made of iron (here, SPCC (cold rolled steel plate)), which is a magnetic material, and both are designed to be long flat plates. As shown in FIG. 9A, each of the magnetic bodies 83 and 84 is designed so that the width W4 is 10 mm, the thickness T4 is 1 mm, and the length L4 in the longitudinal direction is 22 mm. As shown in FIG. 9A, the fourth magnetic body 83 is spaced a certain distance G3 (= 3 mm) from one side surface (the left surface in FIG. 8A) of the fixed contact plate 42 and the arc traveling plate 70. Arrange. Further, as shown in FIG. 9A, the fifth magnetic body 84 has a fixed gap G3 (= 3 mm) from the other side surface (the right surface in FIG. 8A) of the fixed contact plate 42 and the arc traveling plate 70. Place with a gap. Accordingly, the magnetic bodies 83 and 84 are electrically insulated from both the fixed contact plate 42 and the arc traveling plate 70.

  Since the magnetic field B2 generated around the arc A1 passes through each of the magnetic bodies 83 and 84, the magnetic field B2 can be increased, and the magnetic flux density interlinked with the arc current I1 can be increased in the first region. . Therefore, by arranging the magnetic bodies 83 and 84, the Lorentz force acting on the arc A1 can be increased, and the arc A1 generated between the contacts can be more quickly guided to the arc extinguishing grid 71.

  For example, in the model shown in FIG. 9A, when the fixed contact plate 42 and the arc traveling plate 70 are designed with copper, the third Lorentz force F3 is 9.378 N, which is 19.0% larger than the basic model. In addition, in the model of the figure, when each plate 42 and 70 is designed with iron, the 3rd Lorentz force F3 is set to 10.36N, 36.2% larger than a basic model. In the model shown in FIG. 9B, when the fixed contact plate 42 and the arc traveling plate 70 are designed with copper, the third Lorentz force F3 is 11.892N, which is 50.9% larger than the basic model. In the model shown in the figure, when the plates 42 and 70 are designed with iron, the third Lorentz force F3 is 12.442 N, which is 57.9% larger than the basic model. In the model shown in FIG. 9C, when the fixed contact plate 42 and the arc traveling plate 70 are designed with iron, the third Lorentz force F3 is 14.464N, which is 83.6% larger than the basic model.

  By the way, in the circuit breaker of this embodiment, the assembly screw 12 is provided so that it may be covered with the fixed contact plate 42, as shown in FIG. The assembly screw 12 is provided at a position where the magnetic field B1 generated around the fixed contact plate 42 passes. Therefore, if the assembly screw 12 is formed of a magnetic material such as iron, the magnetic field B1 is increased, and the magnetic flux density interlinking with the arc current I1 in the first region can be increased. In this configuration, the Lorentz force acting on the arc A1 can be further increased, and the arc A1 generated between the contacts can be guided to the arc extinguishing grid 71 more quickly.

  In the circuit breaker of the present embodiment, the flat magnetic body 8 is arranged so as to cover the periphery of the fixed contact plate 42 and the arc traveling plate 70. For example, the magnetic breaker 8 has a semicircular arc shape in cross section. You may cover the circumference | surroundings of each board 42 and 70. FIG. Moreover, in the circuit breaker of this embodiment, although the magnetic body 8 is provided in any of the fixed contact plate 42 and the arc traveling plate 70, it is sufficient that the magnetic body 8 is disposed on at least one of them. Moreover, in the circuit breaker of this embodiment, although iron is used as the material of the magnetic body 8, the magnetic body 8 may be formed from other magnetic materials.

  The circuit breaker of the present embodiment is configured to guide the arc A1 to the arc extinguishing grid 71, but may be configured not to include the arc extinguishing grid 71. For example, even when an arc extinguishing space for escaping the arc A1 is provided instead of the arc extinguishing grid 71, the circuit breaker of this embodiment can quickly guide the arc A1 to the arc extinguishing space. .

  Moreover, the circuit breaker of this embodiment can be used as both an AC circuit breaker and a DC circuit breaker. When the circuit breaker of this embodiment is used as a DC circuit breaker, the fourth magnetic body 83 and the fifth magnetic body 84 may be configured with permanent magnets magnetized in a specific direction.

42 Fixed contact plate (induction member)
70 Arc travel plate (induction member)
8 Magnetic material

Claims (4)

An induction member that induces an arc generated between the contacts in a direction away from the contacts by the action of an electromagnetic field;
A magnetic body disposed in the vicinity of the induction member and electrically insulated from the induction member;
The circuit breaker, wherein the magnetic body is arranged so that a magnetic field generated around the induction member passes therethrough.   2. The circuit breaker according to claim 1, wherein the magnetic body is configured to cover at least a part of a surface around a surface of the induction member excluding a surface on which the arc travels.   The circuit breaker according to claim 1 or 2, wherein the magnetic body is arranged so that a magnetic field generated around the arc passes therethrough. Comprising a container housing the guiding member;
The container is configured by connecting a plurality of members to each other by an assembly screw,
The circuit breaker according to any one of claims 1 to 3, wherein the assembly screw is arranged so that a magnetic field generated around the induction member passes and is formed of a magnetic material.

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