JP2008226632A - Circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit breaker in which arc resistance is improved by reducing wear of a grid of a deion type arc extinguishing chamber due to arc. <P>SOLUTION: An arc extinguishing chamber 10 of deion grid type is installed at a current cut-off part of a circuit breaker, and the arc extinguishing chamber 10 includes a grid which is arranged along the opening movement route of a movable contactor 3 and has a V-shape cut-out groove 12a formed in the center of the plate surface. A wedge-shape central partition wall 14 made of a polymer material of insulating object is provided at the rear side on the grid plate surface on the extension line of the V-shape cut-out groove 12a as a wind direction guiding member to divert the arc extinguishing gas flow to right and left by dividing like the arrow heads P1, P2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a circuit breaker for wiring breakers, earth leakage breakers and the like, and more particularly to a structure of a der ion grid type arc extinguishing chamber mounted on a circuit breaker.

  First, the whole structure is shown in FIG. In FIG. 2, 1 is a main body case of a circuit breaker, 2 is a stationary contact united with a power supply side terminal, 2a is a stationary contact, 2b is an arc horn extending from the stationary contact to an arc extinguishing chamber described later, 3 is a movable movable contact, 3a is a movable contact, 4 is a load side terminal, 5 is a contact holder for the movable contact 3, 6 is an opening / closing mechanism for the movable contact 3, 7 is an operating handle, and 8 is a trip. A crossbar 9 is an overcurrent tripping device (bimetal type), and a der ion grid type arc extinguishing chamber 10 is disposed in the current interrupting portion.

  Next, FIGS. 3A and 3B show a conventional structure of the current interrupting portion provided with the der ion grid arc extinguishing chamber 10 described above. In other words, the derion grid type arc extinguishing chamber 10 includes a plurality of grids arranged between the side walls (insulating material) 11 facing left and right, and the left and right side walls arranged side by side along the opening movement path of the movable contact 3. (Arc-extinguishing plate) 12 and an assembly of a slit arc-extinguishing plate (polymer material) 13 arranged on the grid 12 and provided on the entrance side of the arc-extinguishing chamber 10.

Here, the grid 12 is a magnetic plate having a substantially U shape as a whole, and has a groove width toward the entrance side of the arc extinguishing chamber 10 (opening movement path side of the movable contact 3) at the center of the plate surface. An expanding V-shaped cut groove 12a is formed. The main body case 1 is closed around the current interrupting portion by an interphase partition wall except for the gas exhaust opening that opens to the back surface (exit side) of the arc extinguishing chamber 9.
The current interrupting operation of the circuit breaker configured as described above is well known, and when an overcurrent (such as a short circuit current) flows in the main circuit, an electromagnetic driving force acting between the fixed contact 2 and the movable contact 3 is generated. In response to this, the movable contact 3 is opened in the direction of the arrow shown in the figure. At the same time, the arc arc generated between the fixed / movable contacts is driven toward the arc extinguishing chamber 10 by electromagnetic force, and the V-shaped cut groove 12a of the grid 12 is caused by the deviation of the magnetic flux distribution passing through the grid 12 by the magnetic field of the arc current. And is divided between the grids 12 arranged in the upper and lower stages, and an increase in voltage drop and a cooling action are added. Further, the arc column is narrowed down by the gas pressure of the arc gas (high temperature and high pressure) generated in the current interrupting portion, and further, the arc gas flow that flows from the inlet side of the arc extinguishing chamber 10 toward the back gas exhaust port through the gap between the grids. The split arc leg displaces and cools on the plate surface of the grid 12, whereby the arc voltage increases, the arc between the fixed / movable contacts disappears, and the current is interrupted.

On the other hand, with respect to the derion grid type arc extinguishing chamber, an arc dividing member made of an insulating material is inserted in the center of the grid along the depth direction of the arc extinguishing chamber so as to divide the grid into left and right surface areas, and the arc extinguishing chamber is extinguished. There is known a configuration in which the arc drawn into the arc chamber is divided into two arc columns on the left and right by the dividing member, the arc diameter is narrowed, and the arc voltage is increased to improve the current limiting interruption performance (for example, Patent Documents). 1).
JP 2006-12540 A

  By the way, the aforementioned der ion grid type arc extinguishing chamber is required to have a high arc resistance (durability) mechanically from the viewpoint of ensuring the reliability of the product, in addition to the current limiting interruption performance. That is, when the grid 12 made of a magnetic metal material is repeatedly exposed to a high-temperature arc generated when the current is interrupted, the surface of the metal plate is evaporated and worn. In this case, since the arc drawn into the arc extinguishing chamber 10 is concentrated on the V-shaped notch groove 12a formed at the center of the grid 12, the worn portion of the grid 12 is also centered on the V-shaped notch groove 12a. The wear of the grid arc is concentrated faster than the other surface areas because it concentrates on the extension line of the V groove where the legs of the grid arc are displaced. Further, if this grid wear progresses excessively, the grid 12 itself may break from the center and cause a trouble that the original arc extinguishing function cannot be exhibited.

  Therefore, conventionally, as a safety measure for avoiding grid breakage caused by excessive wear, when the depth dimension L of the grid 12 shown in FIG. 3B is determined, the depth is multiplied by a high safety factor in advance. The present situation is that the dimension L is designed to be longer. However, when the depth dimension L of the grid 12 is increased, the outer size of the arc-extinguishing chamber 10 increases accordingly, and the space occupied by the arc-extinguishing chamber 10 occupying in the main body case of the circuit breaker increases, making it difficult to make the product compact and compact. It becomes.

  On the other hand, the wear of the grid 12 due to contact with the high-temperature arc increases as the concentration of the arc pushed into the arc extinguishing chamber (arc constriction, current density) increases. The arc current density, and hence the arc energy density, can be reduced if the foot (arcing point) can be diffused over a wide area on the grid surface. It is possible to increase the arc resistance. In such a point, as in Patent Document 1, the arc drawn into the arc extinguishing chamber by the arc dividing member arranged in the full length region at the center of the plate surface along the depth direction of the grid is divided into the left and right, and the grid is narrowed down. Although the current absolute value of each arc column divided in half above is halved, the current density of the arc in contact with the grid plate surface is the same as before the division, so the concentration and progress of grid wear are not reduced, and the arc extinguishing chamber A sufficient improvement in mechanical arc resistance cannot be expected.

  The present invention has been made in view of the above points, and an arc drawn into the arc extinguishing chamber by adding a wind direction guide member of a simple gas flow on the plate surface of the grid that constructs the derion type arc extinguishing chamber. An object of the present invention is to provide an improved circuit breaker that can diffuse a wide area on the grid surface to reduce wear on the grid, improve arc resistance, and make the arc extinguishing chamber compact and compact.

In order to achieve the above object, according to the present invention, a circuit breaker equipped with a der ion grid type arc extinguishing chamber in a current interrupting unit, the arc extinguishing chamber is arranged along the opening moving path of the movable contact. In the case where a grid is provided, and a V-shaped notch groove is formed toward the entrance side of the arc extinguishing chamber at the center of the plate surface of each grid,
Wind direction that divides the arc gas flow that flows through the arc extinguishing chamber from the current interrupting portion toward the gas exhaust port and diverts to the left and right on the rear side of the grid plate surface, aligned with the extension line of the V-shaped notch groove of the grid A guide member is provided (Claim 1), and the wind direction guide member is specifically configured in the following manner.
(1) The shape of the wind direction guide member is a wedge-shaped shape that tapers toward the entrance side of the arc extinguishing chamber.
(2) The said wind direction guide member is comprised with the insulator of the polymeric material which touches a high temperature arc and discharge | releases arc-extinguishing gas (Claim 3).

  With the above configuration, the arc generated between the fixed / movable contacts at the time of current interruption and electromagnetically driven toward the arc extinguishing chamber is intensively drawn toward the V-shaped notch groove of the grid as in the conventional case, and Divided between. On the other hand, the arc gas that flows into the arc-extinguishing chamber from the inlet side and flows through the gap between the grids toward the exhaust outlet side behind the arc generated at the current interrupting part is provided on the rear side of the center of the grid plate surface. It is divided into two by the wedge-shaped wind direction guide member and flows so as to deviate in the left and right directions.

  As a result, the arc that reaches the V-shaped groove of the grid and is divided between the upper and lower grids is interfered with the arc gas flow and spreads in the left-right direction on the plate surface of the grid so that the arc diameter increases. Become. As a result, the arc current density passing through the grid is reduced, and the intensive wear and excessive progress of the grid can be suppressed and the arc resistance of the grid can be increased. Further, by improving the arc resistance, the design depth dimension L of the grid described in FIG. 3 can be reduced, and the arc extinguishing chamber and the circuit breaker mounting the arc extinguishing chamber can be reduced in size and size.

Embodiments of the present invention will be described below based on the examples shown in FIGS. 1 (a) and 1 (b). In addition, the same code | symbol is attached | subjected to the member corresponding to FIG. 3 (a), (b) in the figure.
That is, the current interrupting portion of the illustrated embodiment is basically the same as the conventional structure shown in FIG. 3, but the arc gas wind direction guide member is provided between the plate surfaces of the grids 12 arranged in the upper and lower stages with a gap therebetween. A center partition wall 14 having the following structure is newly added.

The center partition 14 is an insulator made of a polymer material such as polyamide resin, and its shape is a wedge shape tapered toward the entrance side of the arc extinguishing chamber 10, and its plate thickness corresponds to the gap between the grids. It is arranged on the rear side on the plate surface of the grid 12 so as to be aligned with the extended line of the V-shaped notch groove 12a formed at the center of the grid 12.
With the above configuration, the high-temperature and high-pressure arc gas that is generated in the surrounding area together with the arc arc generated between the fixed / movable contacts at the time of interruption of current and flows through the inside of the arc extinguishing chamber 10 from the inlet side toward the exhaust outlet behind, Due to the wind guide action of the center partition wall 14, the flow is divided into two flows as shown by the arrows P1 and P2 in the figure, and flows so as to deviate in the left and right directions in the arc extinguishing chamber.

As a result, the arc arc that is ignited and extended between the fixed / movable contacts, is intensively drawn into the V-shaped notch groove 12a of the grid 12 by electromagnetic force, and is divided between the grids 12 arranged in the upper and lower stages, Due to the interference action with the arc gas flows P1 and P2, the arc diameter is increased by diffusing horizontally on the plate surface of the grid 12 as shown in the figure.
As a result, the current density of the arc divided between the grids is reduced corresponding to the arc diffusion, the concentration of arc heat applied to the grid 12 is reduced, and the wear and progress of the grid are reduced. Further, arc extinguishing gas is generated from the center partition wall 14 that is directly exposed to the arc and contributes to extinction of the arc.

  Thereby, the arc extinguishing chamber 10 maintains the original arc extinguishing function, and the arc resistance (durability) of the grid 12 is increased as compared with the conventional structure, thereby improving the reliability of the product. Further, as the arc resistance is improved, the depth dimension L of the grid 12 shown in FIG. 3B is reduced to make the arc extinguishing chamber 10 and the circuit breaker mounted with the arc extinguishing chamber smaller and more compact. Can be configured.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the electric current interruption part of the circuit breaker by the Example of this invention, (a) is sectional drawing of a side view, (b) is a top view of (a). Overall structural diagram of a circuit breaker for wiring that is an object of the present invention FIG. 3 is a conventional structural view of a current interrupting portion in FIG. 2, (a) is a sectional side view, (b) is a plan view of (a).

Explanation of symbols

2 fixed contact 2a fixed contact 3 movable contact 3a movable contact 10 derion grid type arc extinguishing chamber 11 side wall 12 grid 12a V-shaped notch 14 center partition wall (wind direction guide member)
arc Arc P1, P2 Arc gas flow

Claims (3)

A circuit breaker equipped with a der ion grid type arc extinguishing chamber in a current interrupting section, wherein the arc extinguishing chamber includes a grid arranged along the opening movement path of the movable contact, and the plate surface of each grid In the center formed a V-shaped cutout groove toward the entrance side of the arc extinguishing chamber,
A wind direction guide member is provided on the rear side of the grid plate surface in alignment with the extended line of the V-shaped notch groove of the grid and diverts the flow of the arc gas flowing through the arc extinguishing chamber to the left and right. Circuit breaker to do. 2. The circuit breaker according to claim 1, wherein the airflow direction guide member has a tapered wedge shape toward the entrance side of the arc extinguishing chamber. 3. The circuit breaker according to claim 1, wherein the wind direction guide member is an insulating material made of a polymer material.

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