JP2012221701A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit breaker capable of efficiently extinguishing arc in a DC circuit or a low-current region.SOLUTION: A circuit breaker comprises: a movable contact piece for opening and closing a main circuit; a movable contact joined to the movable contact piece; a fixed contact arranged at a position facing the movable contact; a fixed contact piece supporting the fixed contact; an arc-extinguishing device for extinguishing arc generated between the movable contact and the fixed contact; an opening/closing mechanism for opening and closing the movable contact piece; a tripping device for detecting overcurrent in the main circuit and opening the movable contact piece; a body case housing the contacts, the contact pieces, the arc-extinguishing device, the opening/closing mechanism and the tripping device; and a body cover covering the body case. A recess is provided on the rear side of the body case on which the fixed contact is arranged, and a magnet is inserted and fixed into the recess of the body case.

Description

  The present invention relates to a circuit breaker that protects an electric circuit from an overcurrent.

  In general, a circuit breaker has a main contact portion including a fixed contact and a movable contact, an open / close mechanism that opens and closes both contact points of the main contact portion, and an overcurrent that exceeds the rated current flows in the main contact portion. A tripping mechanism for performing a circuit breaking operation that sometimes separates the movable contact from the fixed contact and an overcurrent relay mechanism that operates the tripping mechanism are provided. The overcurrent relay mechanism is equipped with a bimetal as a mechanism that operates when the magnitude of the overcurrent is not relatively excessive, and the bimetal has a heater that generates heat commensurate with the overcurrent. The tripping mechanism is activated by a bimetal operation based on the generated heat, thereby opening the main circuit.

  Moreover, the breaking operation in the circuit breaker is performed by restoring the insulation voltage between the contacts by opening the contacts. At this time, an arc is generated between the contacts, and it is known that a voltage at both ends (hereinafter referred to as an arc voltage) increases as the contact opening distance of the contact increases. The arc is quickly transferred to the arc extinguishing device, and the arc is extinguished by the arc extinguishing action of the arc extinguishing device, thereby recovering the insulation voltage between the contacts.

  In addition, when using a circuit breaker in a DC circuit such as a photovoltaic power generation system recently, it always has the same pole and there is no current zero, so the arc extinguishing time is longer than when using it in an AC circuit. . Therefore, there is a method in which an electromagnetic force is applied to the arc by arranging the magnets to stretch the arc and increase the arc voltage. In this method, it is necessary to insulate the magnet when it is arranged in the vicinity of the contact. For example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 10-31952), it is installed in a synthetic resin holder. There is.

Japanese Patent Laid-Open No. 10-31952

  Patent Document 1 discloses that in a circuit breaker, a magnet 41 is arranged near the movable contact 14 and the fixed contact 15 and the arc between the contacts 14 and 15 is discharged outside in accordance with Fleming's left-hand rule. It is disclosed that 41 is held by a synthetic resin holder 40 and the holder 40 is engaged with the grooves 42a and 42b of the container.

  Generally, when a magnet is arranged away from a fixed contact or a movable contact, the electromagnetic force by the magnet becomes smaller in proportion to the distance from the contact. Therefore, an efficient arc extinguishing action cannot be obtained. On the other hand, when arranged near the contact point, the electromagnetic force increases, so that the efficiency of the arc extinguishing action is improved. However, as in Patent Document 1, an insulating cover that insulates the magnet is necessary, and thus the cost is increased. there were.

  In the above structure, the electromagnetic force for transferring the arc to the arc extinguishing device is proportional to the magnetic flux generated by the energized current, so the electromagnetic force is smaller in the low current region than in the high current region. There has been a problem that the time for transferring the arc to the arc extinguishing device becomes long.

  In the conventional structure, the electromagnetic force is applied to the arc-extinguishing device side to stretch the arc.If the magnet polarity is reversed, the electromagnetic force is applied to the opposite side of the arc-extinguishing device. There was a problem that could not be obtained.

  An object of the present invention is to provide a circuit breaker that eliminates the above object and efficiently extinguishes an arc in a short time in a DC circuit or a low current region.

  To achieve the above object, the present invention provides a movable contact for opening and closing a main circuit, a movable contact joined to the movable contact, a fixed contact disposed at a position facing the movable contact, A fixed contact for supporting the fixed contact, an extinguishing device for extinguishing an arc generated between the movable contact and the fixed contact, an opening / closing mechanism for opening and closing the movable contact, A tripping device that detects an overcurrent of a main circuit and opens the movable contact, a main body case that houses the contact point, a contact and extinguishing device, an opening / closing mechanism, and a tripping device, and the main body case. A circuit breaker including a main body cover for covering is characterized in that a concave portion is provided on the back side of the main body case where the fixed contact is disposed, and a magnet is inserted into the concave portion of the main body case and fixed.

  The magnet installed in the circuit breaker is characterized in that the direction of the magnetic pole is arranged so as to be in the axial direction connecting the power supply side terminal and the load side terminal of one pole.

  According to the present invention, since the arc is stretched by the electromagnetic force generated by the magnet immediately after the contact is opened, the time for transferring the arc to the arc extinguishing device is shortened and an efficient arc extinguishing action is obtained. Furthermore, because the electromagnetic force acts in the interphase direction of the circuit breaker, the same effect can be obtained even when the energizing direction of the circuit breaker is reversed. Therefore, efficient arc extinguishing regardless of the polarity of the magnet The effect can be obtained. Also, by inserting and fixing the magnet in the recess on the back of the case, the cover is unnecessary because the magnet is insulated with the resin case, so that the assembly workability is good, the arc extinguishing action is efficient, and it is small and inexpensive. A simple circuit breaker can be provided.

It is sectional drawing which shows the structure of the circuit breaker of this invention. It is sectional drawing which shows the magnet arrangement | positioning of this invention. It is explanatory drawing which shows the principle of this invention. It is explanatory drawing which shows the principle of this invention. It is a figure which shows the back surface of the main body case of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Example 1]
FIG. 1 shows a cross-sectional view of the internal structure of the circuit breaker of the present invention.

  In FIG. 1, 1 is a circuit breaker, 11 is a fixed contact, 12 is a fixed contact joined to the fixed contact 11, 13 is a movable contact disposed at a position facing the fixed contact 12, and 14 is a movable contact 13. 15 is an opening / closing mechanism for driving the movable contact 14 to open / close an electric current, 16 is a tripping device for driving the opening / closing mechanism 15 to open a contact when an overcurrent flows, 17 Is an arc-extinguishing device that eliminates an arc generated between the contacts when the contacts are opened, 18 is a power supply side terminal for wiring an electric wire to the circuit breaker 1, and 19 is an electric wire from the circuit breaker 1 to a load. It is a load side terminal for wiring. Reference numeral 20 denotes a handle for opening and closing the contact. Reference numeral 21 denotes a main body case that accommodates the above-described components. Reference numeral 22 denotes a main body cover that covers the main body case 22, both of which are made of resin and are used as insulating materials inside the circuit breaker.

  When an overcurrent flows through the circuit breaker 1 and the tripping device 16 operates, the movable contact 14 operates instantaneously by the switching mechanism 15, and the movable contact 13 is separated from the fixed contact 12. At this time, an inertia that causes a current to flow between the fixed contact 12 and the movable contact 13 works to generate an arc.

  When the circuit breaker is used in an AC circuit, the arc is extinguished because the current zero point is short, but when it is used in a DC circuit, it is difficult to extinguish because there is no current zero point, and the arc is long. In some cases it will persist. Further, if the arc is not generated and disappears, the contact portions of the fixed contact 12 and the movable contact 13 may be dissolved, or gas may be generated and the mold resin may be dissolved. Therefore, it is necessary to be extinguished in a short time.

  In FIG. 1, reference numeral 23 denotes a magnet, and reference numeral 25 denotes a recess provided on the back surface of the main body case 21 for inserting and fixing the magnet 23.

  The extinguishing device 17 is a so-called der ion type in which a plurality of magnetic iron plates 26 having substantially U-shaped cutouts through which the movable contact 14 passes are stacked on the load side and slanted on the power source side at a wide interval. It is. Further, the magnetic iron plate 26 has a substantially U shape, surrounds the periphery of the movable contact 14, and extends to both sides of the movable contact 14.

  FIG. 2 is a partial cross-sectional view showing a configuration of a contact portion which is a main part of the present invention.

  FIG. 2 shows a state in which the fixed contact 12 and the movable contact 13 are opened, and an arc 30 is generated between the fixed contact and the movable contact, and a diagram in which the magnet 23 of the present invention is arranged.

  The magnet 23 is a permanent magnet, and there are types of alloy magnets, ferrite magnets, and rare earth magnets. Any magnet may be used, and those having a large magnetic force are particularly suitable.

  Further, the magnet 23 is disposed almost directly below the fixed contact 12, and a concave portion 25 is provided on the back surface of the main body case 21. The magnet 23 is arranged in such a direction that the magnetic field of the magnet 23 is parallel to the straight line connecting the power supply side terminal 18 and the load side terminal 19 of the circuit breaker 1, and against the arc between the contacts. Place them so that they intersect vertically. Thus, since the recessed part 25 can be formed in the back surface of the main body case 21 by molding, it can manufacture with high precision, can also attach the magnet 23 easily, and can hold | maintain the distance with the fixed contact 12 as designed. Further, the insulation between the fixed contact 12 and the magnet 23 is also possible by the resin of the main body case.

  Next, the effect of the magnet 23 is demonstrated using FIG.3 and FIG.4.

  FIG. 3 shows the structure of the contact portion of the fixed contact and the movable contact, FIG. 3 (a) is a top view thereof, FIG. 3 (b) is a front view thereof, and FIG. 3 (c) is a movable iron plate and a movable iron plate. It is a perspective view showing a contact.

FIG. 3 shows a state in which the arc 30 is generated when the fixed contact and the movable contact are opened when current flows from the power supply side terminal to the load side terminal (arrow 34).
That is, the current flowing through the circuit breaker flows through the fixed contact 11 through the fixed contact 12 as shown by the arrow 34, through the arc 30, through the movable contact 13 and the movable contact 14, and flows from the load side terminal to the load.

The magnet 23 is disposed almost directly below the fixed contact 12, and is disposed so that the power supply side has an N pole and the load side has an S pole. With such a magnet arrangement, the magnetic field generated by the magnet 23 has a magnetic field distribution from the power supply side to the load side as indicated by an arrow 40. Further, as shown in FIG. 3A, the direction of current is an arrow 41 (direction perpendicular to the paper surface from bottom to top), and the direction of the magnetic field is arrow 32 (left to right direction on the paper surface). Therefore, the direction of the force acting on the arc 30 is an arrow 42 (downward direction on the paper) according to Fleming's left-hand rule. That is, the direction of the force acting on the arc 30 is perpendicular to the axial direction connecting the power supply side and the load side, that is, the lower interphase direction that is the direction of the adjacent phase (rightward when viewed from the power supply side). ). Therefore, in the perspective view showing the magnetic iron plate and the movable contact of the extinguishing apparatus of FIG. 3C, the arc 30 is pulled to the left side toward the power source side and contacts the magnetic iron plate 26. The arc 30 in contact with the plurality of magnetic iron plates 26 expands, is divided by the magnetic iron plates 26, and disappears.
With such a configuration, the arc can be extinguished in a short time.

  Next, the case where a current flows from the load side to the power source side when a circuit breaker is used in the DC circuit will be described with reference to FIG.

  4 shows the structure of the contact portion of the fixed contact and the movable contact, FIG. 4 (a) is a top view thereof, FIG. 4 (b) is a front view thereof, and FIG. 4 (c) is a movable iron plate of the silencer and movable. It is a perspective view showing a contact.

FIG. 4 shows a state in which the arc 30 is generated when the fixed contact and the movable contact are opened when a current flows from the load side terminal to the power source side terminal.
That is, the current flowing through the circuit breaker flows through the movable contact 14, through the movable contact 13, then through the arc 30, through the fixed contact 12 and the fixed contact 11, and flows from the power supply side terminal to the power supply side. Is shown.

Since the magnet 23 is arranged almost directly below the fixed contact 12 so that the power source side is an N pole and the load side is an S pole, the magnetic field by the magnet 23 is on the power source side as indicated by an arrow 32 (same as the arrow 40). The magnetic field distribution is directed to the load side. Further, as shown in FIG. 4A, the direction of current is an arrow 41 (direction perpendicular to the paper surface from the top to the bottom), and the direction of the magnetic field is arrow 32 (left to right direction on the paper surface). Therefore, the direction of the force acting on the arc 30 is an arrow 33 (upward direction on the paper surface) according to Fleming's left-hand rule. That is, the direction of the force acting on the arc 30 is perpendicular to the axial direction connecting the power supply side and the load side, that is, the upper interphase direction that is the direction of the adjacent phase (leftward direction when viewed from the power supply side). is there.
Therefore, in the perspective view showing the magnetic iron plate and the movable contact of the extinguishing apparatus in FIG. 4C, the arc 30 is pulled to the right side toward the power source side and contacts the magnetic iron plate 26. The arc 30 in contact with the plurality of magnetic iron plates 26 is divided by the magnetic iron plates 26 and disappears.

  3 and 4 show that the arrangement of the magnet 23 is the N pole on the power source side and the S pole on the load side, and if this pole is placed in reverse, the generation of the arc 30 is reversed, and the arc disappears. The effect is the same with magnetic iron plates in the interphase direction.

  Next, in FIG. 5, the main body cover on which the magnet 23 is installed will be described.

  FIG. 5 shows the back surface of the main body cover 21, and the upper side of the figure is the power supply side and the lower side is the load side. The circuit breaker of the present invention is a two-pole one and is used for a DC circuit. In FIG. 5, reference numeral 25 denotes a recess for inserting and fixing the magnet 23, which is formed almost directly below the fixed contact 12.

Since the main body cover 21 is manufactured by molding a mold resin, the concave portion 25 can be formed with high accuracy. And although the magnet 23 is inserted and fixed in this recessed part, it can arrange | position with high precision and the assembly workability | operativity is favorable. Further, the magnet 23 can insulate not only the fixed contact 12 but also other components. After the magnet 23 is installed, the recess is covered with a resin plate from above and covered.
In FIG. 5, the upper and lower circles indicate the terminal mounting portions on the power supply side and the load side.
Here, a two-pole circuit breaker is shown, but a three-pole circuit breaker has the same configuration and the same effect.

11: Fixed contact, 12: Fixed contact, 13: Movable contact,
14 ... movable contact, 15 ... opening / closing mechanism, 16 ... tripping device,
17 ... Disappearance device, 18 ... Power supply side terminal, 19 ... Load side terminal,
20 ... Handle, 21 ... Body case, 22 ... Body cover,
23 ... Magnet, 25 ... Recessed part of the body case, 26 ... Magnetic iron plate,
30 ... arc, 33, 42 ... direction of electromagnetic force acting on arc 30;
32, 40 ... direction of the magnetic field acting on the arc 30 31, 41 ... direction of the current flowing through the arc 30.

Claims (2)

A movable contact for opening and closing the main circuit;
A movable contact joined to the movable contact;
A fixed contact disposed at a position facing the movable contact;
A stationary contact for supporting the stationary contact;
An extinguishing device for extinguishing an arc generated between the movable contact and the fixed contact;
An opening / closing mechanism for opening and closing the movable contact;
A tripping device for detecting an overcurrent of the main circuit and opening the movable contact;
A main body case housing the contact, contact, extinguishing device, opening / closing mechanism and tripping device;
In a circuit breaker comprising a main body cover for covering the main body case,
A recess is provided on the back side of the main body case where the fixed contact is disposed,
A circuit breaker characterized in that a magnet is inserted and fixed in a recess of the main body case. The circuit breaker according to claim 1,
The circuit breaker is characterized in that the magnet is arranged so that the magnetic pole direction is an axial direction connecting a power supply side terminal and a load side terminal of one pole.

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