JP5760545B2 - Circuit breaker - Google Patents

Description

  The present invention relates to a circuit breaker including a current interrupting unit.

A circuit breaker including a current interrupting unit is known (for example, see Patent Document 1). Next, the configuration and operation will be described with reference to FIGS.
First, in FIG. 3, 1 is a main body case made of mold resin having a vertically divided structure, 2 and 3 are power supply side and load side terminals arranged at both ends of the main body case 1, 4 is an opening / closing mechanism, and 4a is an opening / closing lever thereof. Reference numeral 5 denotes an opening / closing handle, and 6 is an overcurrent tripping device for detecting an overcurrent flowing in the main circuit and tripping the opening / closing mechanism 4. Further, the lower case of the main body case 1 has a pair of left and right fixed contacts 7 and 8 connected to the power source side and load side terminals 2 and 3 as current interrupting portions of the circuit breaker, and respective contacts of the fixed contacts 7 and 8. A movable contactor 9 having a bridge shape with contacts at both ends opposite to each other, a vertically movable contactor holder 10 which is guided and held so that the movable contactor 9 is movable up and down, and is disposed opposite to the opening / closing lever 4a. A grid-type arc extinguishing device including a contact spring (compression coil spring) 11 that presses and urges the contact 9 toward the fixed contacts 7 and 8, and a pair of arc extinguishing grid plates disposed on the left and right sides of the movable contact 9. 12, an arc commutation plate 13 laid on the bottom of the main body case 1 is disposed across the left and right arc extinguishing devices 12. Note that the conductors of the fixed contacts 7 and 8 are bent in a U shape, and extend from the contact points toward the left and right arc extinguishing devices 12 with the arc runner as the arc runner.

  When the opening / closing handle 5 is turned off from the ON state shown in FIG. 3 with the above configuration, the opening / closing lever 4a of the opening / closing mechanism 4 rotates clockwise, and pushes down the contact holder 10 against the contact spring 11. Thereby, the movable contact 9 is separated from the fixed contacts 7 and 8 and disconnects the energization path.

  On the other hand, when an overload current or a short-circuit current flows in the main circuit, the overcurrent tripping device 6 operates to release the lock of the opening / closing mechanism 4, and the opening / closing lever 4a is moved by the opening / closing spring of the opening / closing mechanism 4. By rotating clockwise, the contact holder 10 is pressed down to open the movable contact 9. In this case, particularly when an excessive current such as a short-circuit current flows, an electromagnetic repulsive force acting between the stationary contacts 7 and 8 and the movable contact 9 is received without waiting for the tripping operation of the switching mechanism 4. Then, the movable contact 9 is separated from the fixed contacts 7 and 8, and the arc generated between the fixed and movable contacts is extended and driven toward the left and right arc extinguishing devices 12 (see FIG. 4A). . In addition, when the movable contact 9 moves apart to near the position of the opening end in this operation process, the arc is transferred from the movable contact 9 to the arc commutation plate 13, and the arc commutation plate 13 is moved and turned off. As is well known, the arc device 12 is pushed into the arc device 12 where the arc is divided into arc extinguishing grid plates to cut off the current limit (see FIG. 4B).

  By the way, when the arc generated between the fixed / movable contacts in the process of interrupting the short-circuit current is transferred from the movable contact 9 to the arc commutation plate 13 and the current is commutated to the arc commutation plate, the movable contact 9 No current will flow through. For this reason, the electromagnetic repulsive force between the fixed / movable contacts also disappears, and the movable contact 9 receives the spring load of the contact spring 11 and is pushed back toward the closed position. In this case, if the opening / closing mechanism 4 operates and pushes down the contact holder 10 before the movable contact 9 is pushed back to the closing position, the movable contact 9 is restrained by the contact holder 10 and opened. However, if there is a delay in the start of the tripping operation of the overcurrent tripping device 6 and the opening / closing mechanism 4 due to the energization state at the time of interrupting the current, the movable contactor via the contactor holder 10 as it is Before 9 is constrained to the open position, the movable contact 9 moved to the open position by the electromagnetic repulsive force is pushed back to the closed position, and as a result, the fixed contacts 7, 8 and the movable contact 9 There is a problem that the gap is re-ignited to deteriorate the breaking performance.

  Therefore, as a countermeasure for the above-described problem, the movable contact between the current flowing in the movable contact in the process of interrupting the short-circuit current commutating to the arc commutation plate and the time when the tripping operation of the opening / closing mechanism is established is established. In order to keep the contact at the open position so that it is not pushed back to the closed position by the drag of the contact spring, the movable contact is made of a magnetic material such as a steel plate and placed behind this movable contact. A circuit breaker having a structure in which a magnetic yoke magnetized by the current flowing through the arc commutating plate is provided on the arc commutating plate side so that the movable contact of the magnetic material is attracted and held at the open position is known. (For example, refer to Patent Document 2).

JP 2000-340093 A (FIG. 7) Japanese Patent No. 4090948 (FIGS. 1 and 2)

  By the way, the circuit breaker having the configuration disclosed in Patent Document 2 has the following problems. That is, the movable contact itself is made of a magnetic material such as a steel plate in order to attract and hold the movable contact magnetically at the open position when the short-circuit current is interrupted. However, the magnetic steel plate has higher electrical resistance than copper, so the movable contact itself generates heat due to the Joule heat loss of the current flowing through the movable contact even during normal operation. The internal temperature of the circuit breaker rises inside. In addition, when the internal temperature rises, the bimetal characteristics of the thermal overcurrent trip device mounted on the circuit breaker fluctuate, causing the circuit breaker to mistrip below the preset current value and stop the motor during operation. There is also a risk of causing problems such as.

  The present invention has been made in view of the above points, and its object is to fix the prior to the tripping operation of the opening / closing mechanism when the short-circuit current is interrupted while solving the above-mentioned problems and ensuring high energization performance of the movable contactor. An object of the present invention is to provide an improved circuit breaker that can attract and hold a movable contact that is opened by an electromagnetic repulsive force between the movable contacts at an open position.

In order to achieve the above object, according to the present invention, a pair of left and right stationary contacts communicating with a power source side and a load side terminal, and a stationary contact of the stationary contact by being guided and held by a contact holder linked to an opening / closing mechanism. A bridge-shaped movable contact disposed opposite to the contact, a contact spring that presses and urges the movable contact toward the fixed contact, a pair of grid-type arc extinguishing devices disposed on the left and right sides of the movable contact, A current interrupting unit consisting of an arc commutation plate laid across the arc-extinguishing device at the opening side of the movable contact is mounted on the main body case, and when a short-circuit current flows in the main circuit In the circuit breaker which is configured to transfer the arc generated between the contact of the movable contact and the fixed contact opened by the electromagnetic repulsive force to the arc commutation plate to cut off the current.
A magnetic material is laminated on the back surface of the movable contact made of a highly conductive material so as to cover the entire movable contact, and the arc commutation plate has an arc commutation with the magnetic surface facing the magnetic material. A U-shaped magnetic yoke that is magnetized by a current flowing through the plate is provided , and the magnetic yoke is configured such that both side surfaces of the U-shape extend from one end to the other end in the longitudinal direction of the movable contact. . Specifically, it can be configured in the following manner.
(1) the arc commutation plate is made of a magnetic material, it is formed integrally with the magnetic yoke and the arc commutation plate (claim 2).
(2) The arc commutation plate and the magnetic yoke are configured as separate parts, and a U-shaped magnetic yoke is disposed so as to surround the arc commutation plate.
(3) The movable contact is constituted by a clad material in which a good conductive material and a magnetic material are bonded together.

  According to the above configuration, the current that has been flowing to the movable contact that has been opened by the electromagnetic repulsion between the fixed and movable contacts before the opening / closing mechanism trips in the process of interrupting the short-circuit current. When commutation occurs in the commutation plate, the magnetic yoke is magnetized by the current flowing through the arc commutation plate. In this state, a magnetic attraction force acts between the magnetic pole surface of the magnetic yoke and the magnetic material laminated on the back surface of the movable contact, thereby opening the movable contact to the open position in the same manner as in the function of Patent Document 2. Can be sucked and held. In addition, since the magnetic body is laminated on the back of the movable contact which becomes a highly conductive material as a separate member, the main circuit current flowing through the movable contact in a normal state of conduction is changed to a highly conductive material having a low electrical resistance. High energization performance can be secured by flowing.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the electric current interruption part concerning Example 1 of this invention, Comprising: (a) is a figure showing the state which the short circuit current flows and the movable contact opened, (b), (c) is ( It is the perspective view of a), and arrow XX sectional drawing. It is a schematic block diagram of the electric current interruption part concerning Example 2 of this invention, Comprising: (a) is a figure showing the state which the short circuit current flows and the movable contact opened, (b), (c) is ( It is the perspective view of a), and arrow XX sectional drawing. It is a structural diagram of a circuit breaker showing a conventional example. It is operation | movement explanatory drawing at the time of the short circuit current interruption | blocking by the circuit breaker of FIG. 3, Comprising: (a), (b) is each immediately after the opening start of a movable contact, and an arc changes from a movable contact to an arc commutation plate. It is a figure showing the state which changed.

  Embodiments of the present invention will be described below based on the examples shown in FIGS. In the drawings of the respective embodiments, members corresponding to those in FIG.

  First, the Example of the electric current interruption part corresponding to Claim 1, 2 is shown to Fig.1 (a)-(c). In the drawing, the contact holder and the contact spring are not shown. In the illustrated embodiment, a magnetic body 14 made of a steel plate or the like is laminated on the back side (the surface opposite to the contact) of the movable contact 9 made of a highly conductive material such as copper. Has been. Further, the arc commutation plate 13 laid on the bottom of the main body case 1 across the arc extinguishing device 12 disposed on the left and right sides of the movable contact 9 is a magnetic material such as a steel plate. An L-shaped magnetic yoke 15 is formed on the flow plate 13 so as to protrude from both side edges of the central portion along the longitudinal direction and to make the magnetic pole surface face the magnetic body 14.

  With the above configuration, during energization during normal times when the movable contact 9 is closed, current flows through the conductor (good conductive material) of the movable contact 9. Here, when a short-circuit current flows through the main circuit, the movable contact 9 is separated from the fixed contacts 7 and 8 by the electromagnetic repulsive force as described in FIG. When the contact 9 moves to a position close to the end of the opening, the arc is transferred to the arc commutation plate 13 as shown, and the current that has been flowing to the movable contact 9 until now flows through the arc commutation plate 13. .

  In this state, as shown in FIG. 1C, the magnetic yoke 15 is magnetized by the magnetic field of the current i commutated to the arc commutation plate 13, and the magnetic flux φ is focused as shown. As a result, the magnetic attractive force F acts between the magnetic yoke 15 and the magnetic pole surface of the magnetic body 14 laminated on the movable contact 9 so that the movable contact 9 is attracted to the magnetic yoke 15. Further, the attracting state of the movable contact 9 continues until the arc disappears and no current flows through the arc commutation plate 13, during which the opening / closing mechanism 4 shown in FIG. 10 is pushed down, and the movable contact 9 is constrained and held at the open position to cut off the short-circuit current. Moreover, since the magnetic body 14 is laminated on the back surface of the movable contact 9 made of a highly conductive material, the movable contact 9 can ensure high energization performance without impairing the energization performance.

Next, an embodiment corresponding to claim 3 of the present invention is shown in FIG. In this embodiment, the magnetic yoke 15 is arranged as a U-shaped independent part so as to surround the arc commutation plate 13. As a result, the arc commutation plate 13 can be smoothly transferred from the movable contact 9 to the arc commutation plate 13 by adopting a conductor having a lower electrical resistance than the magnetic material. it can.

  In addition, the movable contact 9 in the first and second embodiments may be configured by a clad material in which a highly conductive plate material such as copper and a magnetic material plate are bonded together.

DESCRIPTION OF SYMBOLS 1 Main body case 4 Opening-closing mechanism 6 Overcurrent tripping device 7, 8 Fixed contact 9 Movable contact 10 Contactor holder 11 Contact spring 12 Arc extinguishing device 13 Arc commutation plate 14 Magnetic body 15 Magnetic yoke

Claims (4)

A pair of left and right fixed contacts that communicate with the power source side and the load side terminal, a bridge-shaped movable contact that is guided and held by a contact holder linked to an opening / closing mechanism and is disposed opposite to the fixed contact of the fixed contact; A contact spring that presses and urges the movable contact toward the fixed contact, a pair of grid-type arc extinguishing devices disposed on the left and right sides of the movable contact, and the movable contact straddling the arc extinguishing device A movable contact and a stationary contact that are equipped with a current interrupting part that is composed of an arc commutation plate laid at the opening side of the main body and that is opened by electromagnetic repulsion when a short-circuit current flows in the main circuit In the circuit breaker in which the arc generated between the contacts is transferred to the arc commutation plate so as to cut off the current.
While laminating a magnetic body so as to cover the entire movable contact on the back of the movable contact made of a highly conductive material,
The arc commutation plate is provided with a U-shaped magnetic yoke that is magnetized by a current flowing through the arc commutation plate while facing the magnetic pole surface to the magnetic body, and both sides of the U-shaped magnetic yoke have the movable contact. A circuit breaker extending from one end to the other end in the longitudinal direction of the child . The circuit breaker according to claim 1, the arc commutation plate is made of a magnetic material, the circuit breaker being characterized in that formed integrally with the magnetic yoke and the arc commutation plate. It characterized The circuit breaker according to claim 1, after constituting said magnetic yoke and said arc commutation plate as separate parts, in that a said U-shaped magnetic yoke so as to surround the arc commutation plate A circuit breaker.   4. The circuit breaker according to claim 1, wherein the movable contact is made of a clad material obtained by bonding a highly conductive material and a magnetic material.