JPS62208522A - Arc extinguisher for circuit breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Aspects of the Invention] (Industrial Field of Application) The present invention supports a large number of grids in multiple stages on supports disposed opposite to each other to limit and extinguish the arc at the time of interruption. This invention relates to an arc extinguishing device for a circuit breaker.

(Prior art) Conventionally, this type of device uses electromagnetic force to attract the arc generated when the movable contact of the movable contact is separated from the fixed contact of the fixed contact to the grid of the arc extinguisher when the short-circuit current is cut off. The arc is then elongated and cooled to extinguish the arc. and,
Generally speaking, the following relational expression is known for arc resistance.

That is, the arc resistance is R (Ω), and the arc resistivity is p (Ω・
■), the arc length is L(CIll), and the arc cross-sectional area is S(
c+n'), then R-ρXf+S(Ω). However, the arc resistivity p decreases in inverse proportion to the temperature of the arc. Since there is such a relational expression, in order to increase the arc resistance R in order to improve the current limiting performance at the time of interruption, it is necessary to increase the arc resistivity ρ, increase the arc length, or increase the arc cross-sectional area. It would be better if S was made smaller. Therefore, as a method for increasing the arc resistance R and improving the current limiting performance, for example, JP-A-57-806
Listed as those listed in Publication No. 29.

In this device, the fixed contact and the movable contact are coated with an organic or inorganic insulating material other than the contact surfaces where the fixed contacts and the movable contact come into contact. In this way, only the portion where the fixed contact and the movable contact face each other becomes an electrical contact surface,
The conductor portions of the other fixed contacts and movable contacts near this electrical contact surface are covered with an insulator. As a result, the arc cross-sectional area S of the arc that occurs when the movable contact tries to separate from the fixed contact at the time of disconnection is limited by the insulator, and the current density between the contacts is expected to increase. It was hoped that by increasing the amount of metal particles generated, the cooling of the arc space would be promoted and the arc resistivity p would be increased by 2.

(Problem to be Solved by the Invention) However, in the conventional configuration described above, since the movable contact originally moves when the movable contact is cut off, it is necessary to replace the insulating material covering the movable contact with another component. It had the disadvantage that it had to be fixed in place and had poor reliability.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an arc extinguishing device for a circuit breaker which can increase arc resistance and improve current limiting arc extinguishing performance, and which is easy to assemble and has high reliability.

[Structure of the Invention] (Means for Solving the Problems) The arc extinguishing device for a circuit breaker of the present invention has a support body supporting a large number of grids in multiple stages, and movable grids near fixed contacts. It is constructed by placing arc restricting insulators on both sides of the recess that forms the contact movement path, and the arc restricting insulators suppress the spread of the arc and cool the arc to increase arc resistance. It is something.

(Function) When the movable contact is separated from the fixed contact at the time of interruption, an arc is generated between the contacts. At this time, the arc is prevented from spreading and cooled by the arc restricting insulator. This increases the arc resistance and limits the arc.

Furthermore, since the arc pressure on the fixed contact side is higher than the arc pressure on the movable contact side, the current is also limited by the pressure diffusion effect.

As a result, current limiting arc extinguishing performance is improved. Moreover, since the arc restricting insulator is simply disposed in the arc extinguishing device, which is a stationary member, it can be easily assembled.

(Example) An example of the present invention will be described below with reference to the drawings.

First, in FIG. 1, which shows a circuit breaker with a portion cut away, 1 is a vertically elongated case, and an operating handle 2 that protrudes from approximately the center of the case 1 and can be rotated from side to side is disposed. . This operation handle 2 is linked to an opening/closing operation mechanism (not shown), and is rotated to the right when the power is turned on, and to the left when the power is turned off. Reference numeral 3 denotes a power terminal provided at the upper rear surface of the case 1. 4 is power terminal 3
A fixed contact 5 is connected to the fixed contact 5 at the tip of the fixed contact.
is provided. Reference numeral 6 denotes a movable contact that comes into contact with and separates from the fixed contact 5. This is provided at the tip of the movable contact 7, and when the operating handle 2 is rotated to the right, it operates an opening/closing operation mechanism (not shown) and is movable. The contact 7 is rotated toward the fixed contact 4, and the movable contact 6 comes into contact with the fixed contact 5.

The movable contactor 7 is connected to a load terminal via a thermal external body made of a flexible conductor, a heater, a bimetal, etc. (not shown), and an electromagnetic magnetic external body having an armature yoke. When an overload current is detected, a thermal external device is activated to activate an opening/closing mechanism (not shown), and the movable contact 7 is rotated toward the side opposite to the fixed contact 4, and the movable contact 6 is separated from the fixed contact 5, or a short circuit occurs. At the time of current detection, the electromagnetic attraction section operates in the same manner as when overload current is detected, and the movable contact 6 is separated from the fixed contact 5.

Now, 8 is an arc extinguishing device installed in the upper part of case 1.
This consists of two sets of plate-shaped supports 9 made of insulators, and a grid 10 made of a large number, for example seven, of magnetic material, for example iron plates.
and two U-shaped arc restricting insulators 11 (see FIGS. 2 and 3). The support body 9 is formed with a hole 9a for supporting the grid 10 and a groove 9b for fitting the arc restricting insulator 11 (see FIG. 4). The grid 10 has a protrusion 10a1 which is fitted into the punching hole 9a of the support body 9 by punching.
A concave portion 10b forming a moving path of the movable contact and protrusions 10c forming both sides of the four portions 10b are formed (see Fig. 5).
. The arc restricting insulator 11 is formed with a side portion 11a for fitting into the groove 9b of the support 9 (see FIGS. 6 and 7). From the above, a large number (seven) of grids 10 are inserted into the holes 9a and the protrusions 1 are inserted into the supports 9 arranged oppositely.
By engaging 0a, an arc extinguishing device 8 supported in multiple stages (7 stages) is configured, and the recess 1 forms a moving path for the movable contacts of a plurality of (three) grids 10 close to the fixed contacts 5.
On both sides (protruding piece 10c) inside 0b, there is a side part 11a in the groove 9b.
The arc restricting insulator 11 is arranged by engaging with the arc restricting insulator 11.

Next, in the above structure, the operation when the movable contact 6 is separated from the fixed contact 5 due to overload current or short circuit current will be explained with reference to FIGS. 8 to 10.

When the movable contact 6 separates from the fixed contact 5, an arc A is generated between these contacts. The arc current of this arc A is magnetically driven in the direction shown by the solid line in the figure because a biased magnetic field is formed in the grid 10 in the direction shown by the broken line in the figure. As a result, the arc A is guided to the recess 10b of the grid 10, and is extinguished by the cooling action of the grid 10.

By the way, the arc A generated when the movable contact 6 is separated from the fixed contact 5 tries to spread between the contacts as shown in FIG. As a result, the arc cross-sectional area S does not increase, and at the same time, the arc resistivity ρ increases due to contact with the arc restricting insulator 11 and cooling. Since the movable contact 6 is opened at a very high speed, the spread of the arc A on the movable contact 6 side is also suppressed, and the arc resistance R can be expected to increase even in this portion. In this case, the arc A on the fixed contact 5 side is narrowed by the arc restricting insulator 11 and the pressure of the arc A increases, but it is rapidly diffused in the direction of the movable contact 6 due to the pressure diffusion effect.

Due to the increase in arc resistance R and the pressure diffusion effect of the arc, the arc A is current-limited and extinguished.

According to this embodiment, the following effects can be obtained. That is, since the arc A generated when the movable contact 6 is opened is limited by providing the arc restricting insulator 11 on the arc extinguishing device 8 side, which is a stationary member, the arc A generated when the movable contact 6 is opened is limited. Unlike the case where an insulator is provided to limit the current, parts for fixing the insulator are unnecessary or simplified, and reliability is increased. Further, when the arc is extinguished, a difference in arc pressure occurs between the portion where the arc restricting insulator 11 is provided and the other portions, and this pressure difference causes the arc A to undergo a diffusion action, thereby improving the arc extinguishing performance.

Further, at least a portion of the arc restricting insulator 11 of the above embodiment, for example, the opposing contact surface 11b may be formed of a fluororesin, such as polytetrafluoroethylene. In this way, the contact surface 11b is exposed to the high temperature arc A generated when the movable contact 6 is opened, so polytetrafluoroethylene decomposes and negative fluorine ions (F-
) atoms are dissociated into arc space. This F-atom then deposits positive ions forming a space charge layer within the arc space. Therefore, the arc resistivity ρ becomes even larger, so that the arc resistance R can be increased. However, the arc temperature is 5
Since this adhesion effect is significant below 000°, this adhesion effect becomes even more significant when the arc is about to be extinguished, and the arc resistivity ρ becomes even larger, thereby improving the arc extinguishing performance.

Note that the present invention is not limited to the embodiments described above and shown in the drawings; for example, the groove 9b of the support 9 of the arc extinguishing device 8 and the side portion 11 of the arc restricting insulator 11 of the above embodiment
It goes without saying that the embodiments may be modified as appropriate without departing from the scope of the invention, such as replacing a with a punch hole and a protrusion, respectively, by inserting a protrusion into the punch hole and then caulking it.

[Effects of the Invention] As described above, the present invention arranges arc restricting insulators on both sides of the concave portions of a plurality of grids near the fixed contacts, so arc resistance can be increased and current limiting extinguishing can be achieved. This has extremely excellent effects in that the arc can be improved, assembly is simple, and reliability can be improved.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a partially cutaway longitudinal side view of a circuit breaker, Fig. 2 is a front view of the arc extinguisher, and Fig. 3 is a line taken along the line ■-■ in Fig. 2. 4 is a side view of the support, FIG. 5 is a plan view of the grid, FIG. 6 is a plan view of the arc restricting insulator, FIG. 7 is a side view of the same, and FIGS. FIG. 10 is an explanatory diagram of the action when the movable contact is opened. In the drawing, 5 is a fixed contact, 6 is a movable contact, 8 is an arc extinguishing device,
9 is a support, 10 is a grid, 10b is a recess, 10c is a protrusion (on both sides), and 11 is an arc restricting insulator. Applicant Toshiba Corporation Figure 1 Figure 2 Figure 3 ＾ 4 Figure
Figure 5 Man 6 Figure j
P, 7 Figure 78 Figure 9 Figure 10

Claims (1)

[Claims] 1. In an arc extinguishing device in which a large number of grids are supported in multiple stages on supports disposed opposite to each other, on both sides of a recess forming a moving path of a movable contact of a plurality of grids near a fixed contact. An arc extinguishing device for a circuit or disconnection characterized by disposing an arc restricting insulator. 2. The arc extinguishing device for circuits and breakers as set forth in claim 1, wherein at least a portion of the arc restricting insulator is formed of a fluororesin.