JP2012156044A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve current-limiting breaking performance of a circuit breaker by changing the current path, which runs through a stationary and movable contactor, to a loop-shape so that all currents flowing in the stationary and a movable contactor at the time of short-circuit breaking can be effectively utilized for fast movable contactor opening and extended arc drive.SOLUTION: A circuit breaker having a current cutoff part, a make-and-break mechanism part and an overcurrent drawing part mounted inside a main body case comprises: a pair of stationary contactors 7, 8 whose current cutoff parts respectively extend to a power supply side terminal and a load side terminal; a bridge type movable contactor 9; a direct-acting contactor holder having the movable contactor 9 mounted therein and communicates with the make-and-break mechanism part; and a pair of arc-extinguishing chambers 12 disposed along a contact parting path of the movable contactor on both sides thereof. In the circuit breaker, the power supply side and load side stationary contactors 7, 8 are constructed in such a way that their contactor conductors are extended from one end of the movable contactor 9 to the other end on the opposite side, and extended parts 7b, 8b thereof are provided with stationary contacts 7a, 8a disposed at both ends of the movable contactor 9 and opposed to a movable contact 9a.

Description

  The present invention relates to a circuit breaker including a two-point breaking type current breaker configured to open and close an electric circuit with a bridge-shaped movable contact facing a pair of fixed contacts, and more specifically, the current breaker This relates to the arrangement structure of the stationary contacts in FIG.

  For a circuit breaker applied to a low-voltage distribution line, in order to improve the breaking performance, a pair of fixed contacts that are connected to the power supply side terminal and the load side terminal, respectively, and a bridge facing the fixed contact Two points composed of a movable movable contact, a direct-acting movable contact holder mounted on the movable contactor and connected to the opening / closing mechanism, and a pair of arc extinguishing chambers arranged on both sides of the movable contact A circuit breaker of a cut type is known (for example, refer to Patent Document 1).

  Next, FIG. 5 shows a conventional structure of the circuit breaker of the two-point cut type described above. In FIG. 5, 1 is a main body case of a circuit breaker made of a resin case, 2 and 3 are power supply side and load side terminals made of screw terminals, 4 is a current cut-off section, and 5 is a toggle link mechanism. The opening / closing mechanism unit 5a is a combination of a release spring, 5a is an opening / closing operation handle linked to the opening / closing mechanism unit 5, 5b is an output shaft of the opening / closing mechanism unit 5, and 6 is a thermal-electromagnetic overcurrent tripping unit. The current interrupting unit 4 is disposed on the bottom side of the main body case 1 so as to be isolated from the switching mechanism unit 5 and the overcurrent tripping unit 6.

  Here, the current interrupting unit 4 includes a fixed contact 7 connected to the power supply side terminal 2, a fixed contact 8 connected to the load side terminal 3 via the overcurrent tripping unit 6, and a pair of power supply side and load side Up-and-down motion connected to the opening / closing mechanism 5 by mounting the movable contact 9 in a bridge shape facing the lower side of the fixed contacts 7 and 8, and the movable contact 9 and the contact pressure spring 10. Type movable contact holder 11 and a pair of arc extinguishing chambers (grid-type arc extinguishing chambers) arranged on both sides (power supply side and load side) along the opening path of the movable contact 9 ) 12 and an assembly of a commutation plate 13 disposed on the bottom side of the movable contact 9.

  The fixed contacts 7 and 8 are formed by bending the distal end side of the fixed contact into a U-shape as shown in FIG. 6, and providing fixed contacts 7a and 8a on the lower surface of the conductor. The contacts 7a and 8a are opposed to the movable contact 9a disposed at both ends of the movable contact 9.

  The opening / closing operation of the circuit breaker configured as described above is also described in detail in the above-mentioned Patent Document 1. That is, in the closed state of FIG. 5 and FIG. 6A, the main circuit current flows from the power source side terminal 2 through the fixed contact 7 → the movable contact 9 → the fixed contact 8 → the overcurrent tripping portion 6. It flows to terminal 3. The opening / closing mechanism 5 is latched and held by a latch with the release spring stored. When the main circuit current flowing through the circuit breaker from this state becomes an overcurrent state, the overcurrent tripping section 6 responds to release the release spring latch in the opening / closing mechanism section 5. As a result, the release spring that has been stored up until now is released, and the movable contact holder 11 is driven downwardly through the toggle link mechanism and the output shaft 5b. As a result, as shown in FIG. 6B, the movable contact 9 is separated from the fixed contacts 7 and 8 to open the electric circuit. Further, when the operation handle 5a is operated from the ON position to the OFF position in the closed state of the electric circuit, the toggle link mechanism of the opening / closing mechanism section 5 is reversed to release the accumulating force of the release spring. Similarly, the movable contact 9 is opened.

  On the other hand, when a large current such as a short circuit current flows in the electric circuit, the movable contact 9 instantaneously does not wait for the release operation of the opening / closing mechanism section 5 due to the electromagnetic repulsive force acting between the fixed contacts 7 and 8. Driven in the opening direction, the movable contactor 9 is held at the opening end position by the operation of the opening / closing mechanism 5.

  Further, when this short circuit is interrupted, an arc 14 is generated between the movable contact 9a disposed at both ends of the movable contact 9 and the fixed contacts 7a, 8a of the fixed contacts 7, 8 as shown in FIG. . As is well known, the arc 14 is driven to extend toward the arc-extinguishing chamber 12 by the electromagnetic force acting between the stationary contacts 7 and 8 and the current flowing through the movable contact 9 to cut off the current limit. is there.

Japanese Patent No. 4258699

  In order to enhance the current-limiting effect at the time of short-circuit interruption and extinguish the arc as early as possible with the above circuit breaker, the arc is extinguished while the movable contact is opened at high speed as early as possible to stretch the arc for a long time. It is important to drive electromagnetically quickly toward the arc chamber.

  With respect to the current interrupting portion having the conventional structure shown in FIG. 6 and the driving electromagnetic force acting on the movable contact 9 and the arc 14 at the time of short-circuit interruption, the following problems may be encountered. understood.

  In other words, FIG. 7 shows a current cut-off portion of the two-point cut-off type current breaker that combines the U-shaped fixed contacts 7 and 8 and the bridge-shaped movable contact 9 shown in FIG. FIG. 3 is a diagram schematically showing a flow path, a direction, and a direction of a driving electromagnetic force acting on an arc. In the figure, arrows i-1, i-2, i-3, and i-4 indicate the direction of current flowing through each part of the current interrupting unit, and thick line arrows indicate electromagnetic repulsive force and attractive force.

  Here, the movable contact 9 is electromagnetically driven in the opening direction with the addition of electromagnetic repulsive force (Fleming's left-hand rule) due to currents i-2 and i-3 flowing in opposite directions. The arc 14 ignited between the fixed contacts 7a and 8a and the movable contact 9a with the opening of the movable contact 9 generates electromagnetic repulsive forces f-1 and f-2 due to currents i-2 and i-3. Upon receipt, it is electromagnetically driven so as to extend outward (arc extinguishing chamber side).

  On the other hand, when looking at the driving electromagnetic force acting on the movable contact 9 and the arc 14 by the current i-1 flowing in the conductor portion from the terminal side of the fixed contact 7 (the same applies to the fixed contact 8) to the U-bend portion, The movable contact 9 is applied with an electromagnetic attractive force (the current directions of currents i-1 and i-3 are the same) to weaken the opening driving force of the movable contact 9. Further, an electromagnetic attracting force f-3 and an electromagnetic repulsive force f-4 that hinder the outward extension drive to the arc 14 also act on the inside and outside of the arc. In addition, since the leading ends of the conductors of the fixed contacts 7 and 8 are bent in the middle, the electromagnetic driving force in the opening direction hardly acts on the central portion of the movable contact 9 in the longitudinal direction.

  For this reason, in the conventional structure of the current interrupting part, the opening speed of the movable contact 9 in the initial stage of the short circuit is weakened, and the electromagnetic driving force for extending the arc 14 toward the arc extinguishing chamber 12 (see FIG. 5) is also reduced. High current limiting effect.

  The present invention has been made in view of the above points. The object of the present invention is to solve the above-described problems, and to rapidly release the electromagnetic force generated by all currents flowing through the stationary contact and the movable contact during short circuit interruption. A circuit breaker that improves the current-limiting interrupt performance by changing the current path through the fixed contact and movable contact of the current interrupter into a loop shape so that it can be used effectively for the extension drive of the arc. There is to do.

In order to achieve the above object, according to the present invention, there is provided a circuit breaker in which a current interrupting part, a switching mechanism part, and an overcurrent pulling part are incorporated in a main body case, wherein the current interrupting part is a power supply side terminal, a load side terminal. A pair of fixed contacts, a bridge-shaped movable contact facing the fixed contacts, and a direct-acting movable contact holder mounted with the movable contacts and linked to the opening / closing mechanism. , Consisting of a pair of arc-extinguishing chambers arranged on both sides of the movable contact facing the opening movement path,
The power supply side and load side fixed contacts extend the fixed contact conductor from one end side of the movable contact to the opposite end along the longitudinal direction of the movable contact, and then move the movable contact to the extension portion. A fixed contact facing the movable contact disposed at both ends of the child is provided (Claim 1).

In the circuit breaker having the above configuration,
(1) The intermediate portions of the conductors of the fixed contact on the power supply side and the fixed contact on the load side are three-dimensionally crossed to form an extension portion of each fixed contact.
(2) An arc runner whose tip extends toward the arc extinguishing chamber is formed in an extension of the stationary contact on the power source side and the load side (claim 3).

With the above configuration, the following effects can be obtained.
(1) About the fixed contacts on the power supply side and the load side, by arranging the contact conductors as in claim 1, the fixed contact on the load side from the fixed contact on the power supply side via the movable contact The current path leading to is a simple loop shape. As a result, when the short circuit is interrupted, the electromagnetic driving force due to the current flowing through the stationary contact and the movable contact acts in the direction of driving the movable contact in the opening direction, and the opening speed of the movable contact is reduced compared to the conventional structure. Can be increased.

In addition, the arc generated between the fixed contact and the movable contact at the time of short circuit interruption receives a repulsive force from the inside of the arc and an attractive force from the outside by the driving electromagnetic force of the current flowing in the loop-shaped current path. As a result, the arc can be quickly driven to extend toward the arc extinguishing chamber, and the current limiting interruption performance is improved.
(2) Further, in forming the extension portion in the stationary contact, the conductor intermediate portion of the stationary contact on the power source side and the stationary contact on the load side are three-dimensionally crossed with each other (Claim 2). Can form an extension of the stationary contact that flows in the same direction.
(3) Furthermore, by forming an arc runner that extends to the arc extinguishing chamber in connection with the extension of the stationary contact on the power supply side and the load side (Claim 3), the arc generated on the fixed contact is arced. It can be moved to the runner and moved quickly to the arc extinguishing chamber.

It is a block diagram of the electric current interruption part by the Example of this invention, Comprising: (a) is a front view showing the closing state of a movable contact, (b) is XX sectional drawing of arrow (a). It is a front view showing the opening state of the movable contact corresponding to Fig.1 (a). It is a cross-sectional perspective view along the contactor longitudinal direction about the electric current interruption part of FIG. It is the figure which represented typically the electric current path at the time of the short circuit interruption | blocking in the electric current interruption part of FIG. 1, a flow direction, and the direction of the drive electromagnetic force which acts on an arc. It is a figure showing the whole structure of the conventional two-point circuit breaker. FIGS. 6A and 6B are structural diagrams of a current interrupting unit in FIG. 5, and FIGS. 6A and 6B are front views showing a closed state and a state of a short circuit breaking operation, respectively. It is the figure which represented typically the electric current path at the time of the short circuit interruption | blocking in the electric current interruption part of FIG. 6, a flow direction, and the direction of the drive electromagnetic force which acts on an arc.

Embodiments of the present invention will be described below based on the examples shown in FIGS. In addition, in the figure of an Example, the same code | symbol is attached | subjected to the member corresponding to FIG.
That is, in the current interrupting unit of the illustrated embodiment, the power-side and load-side fixed contacts 7 and 8 connected to the power-side terminal 2 and the load-side terminal 3 (see FIG. 5) of the circuit breaker are shown in FIG. The front end portion is extended from one end side to the opposite end without bending the U-shape as in the conventional structure, and the movable contact 9a of the movable contact 9 is formed on the lower surface of the extension portions 7b and 8b. Fixed contacts 7a and 8a are provided.

  Here, the extension 7b of the fixed contact 7 on the power supply side extends downward along the fixed contact 8 on the load side, and the extension 8b of the fixed contact 8 on the load side is the fixed contact on the power supply side. It extends to the lower side along the child 7 and is opposed to the bridge-shaped movable contact 9 at this position. Further, between the contact conductors of the fixed contacts 7 and 8 and the conductors of the extension portions 7b and 8b, there are connected connecting conductors 7c and 8c that obliquely intersect with each other from the opposite directions. 8c is isolated from each other so that the contact conductors are three-dimensionally crossed. Further, the extension portions 7b and 8b of the fixed contacts 7 and 8 extend toward the arc extinguishing chambers 12 arranged on both sides of the movable contact 9 to form arc runners 7d and 8d. Yes.

  With the above configuration, the current path from the fixed contact 7 on the power source side to the fixed contact 8 on the load side through the movable contact 9 is different from the conventional structure (see FIG. 7), and a simple loop as shown in FIG. Follow the path. In FIG. 4, arrows i-1 and i-2 indicate the directions of current flowing through the stationary contact 7 on the power source side and its extension 7b. Arrows i-3 and i-4 indicate the directions of current flowing through the movable contact 9 and the arc 14, respectively. Arrows i-5 and i-6 indicate the load-side fixed contact 8 and its extension 8b. It represents the direction of the flowing current.

  As can be seen from the loop-shaped current path described above, the currents flowing through the fixed contacts 7 and 8 and their extensions 7b and 8b and the transition conductors 7c and 8c are all in the same direction, and the current flowing through the movable contact 9 Is the opposite. As a result, the currents i-1, i-2, i-5, i-6 flowing through the stationary contacts 7, 8 and their extensions 7b, 8b are all electromagnetic forces that drive the movable contact 9 in the opening direction. Will work. Thereby, compared with the conventional structure described in FIG. 7, the electromagnetic driving force in the opening direction acting on the movable contact 9 is enhanced, and the opening speed at the time of short-circuit interruption can be greatly increased.

  For the arc 14 generated between the fixed contacts 7a, 8a of the fixed contacts 7, 8 and the movable contact 9a of the movable contact 9, the current i− flowing along the loop-shaped current path. 1 to i-6 cause the electromagnetic repulsive forces f-1 and f-2 and the electromagnetic attractive force f-4 represented by arcuate thick arrows in FIG. 4 to act on the inside and the outside of the arc 14, respectively. The arc 14 is electromagnetically driven toward the arc extinguishing chamber 12 (see FIG. 2) (Fleming's left-hand rule). Further, by this electromagnetic drive, the arcing point of the arc 14 is transferred from the fixed contacts 7 a, 8 a of the fixed contacts 7, 8 a to the arc runners 7 d, 8 d, and quickly moves toward the arc extinguishing chamber 12. As a result, the generation of electromagnetic force that hinders the extension of the arc 14 which has been a problem in the conventional structure (see FIG. 7) is eliminated, and in addition to the effect of increasing the breaking speed of the movable contact 9 described above, The current limiting interruption performance can be greatly improved.

DESCRIPTION OF SYMBOLS 1 Main body case 2 Power supply side terminal 3 Load side terminal 4 Current interrupting part 5 Opening and closing mechanism part 6 Overcurrent tripping part 7 Power supply side fixed contact 8 Load side fixed contact 7a, 8a Fixed contact 7b, 8b Fixed contact Extension part 7c, 8c Transition conductor 7d, 8d Arc runner 9 Bridge-shaped movable contact 9a Movable contact 10 Contact pressure spring 11 Movable contact holder 12 Arc extinguishing chamber

Claims (3)

A circuit breaker in which a current interrupting part, an opening / closing mechanism part, and an overcurrent pulling part are incorporated in a main body case, wherein the current interrupting part is connected to a power supply side terminal and a load side terminal, respectively, and a pair of fixed contacts A bridge-shaped movable contact that faces the child, a direct-acting movable contact holder that is mounted with the movable contact and linked to the opening / closing mechanism, and an opening moving path of the movable contact. In what consists of a pair of arc extinguishing chambers arranged on both sides,
The power supply side and load side fixed contacts extend the fixed contact conductor from one end side of the movable contact to the opposite end along the longitudinal direction of the movable contact, and then move the movable contact to the extension portion. A circuit breaker comprising a fixed contact facing the movable contact disposed at both ends of the child.   2. The circuit breaker according to claim 1, wherein a conductor intermediate portion of the power-side fixed contact and the load-side fixed contact are three-dimensionally crossed to form an extension portion of each fixed contact. Circuit breaker. 3. The circuit breaker according to claim 1 or 2, wherein an arc runner whose tip extends toward the arc extinguishing chamber is formed at an extension of the stationary contact on the power source side and the load side. Circuit breaker.