KR100224916B1 - Circuit breaker - Google Patents

Abstract

An object of the present invention is to provide a drive coil between a stationary contact plate and a power supply side terminal, and to reduce the width of the drive coil in the width direction. The solution means includes a plurality of magnetic materials between the power supply side terminal 24, the drive coil 25, the fixed contactor 21 having the fixed contact plate 26, and the side plate 29 of the insulation agent in the arc extinguishing chamber of the case. The arrangement | positioning apparatus of the extinguishing apparatus 22 which has the grid plate 30 to multistage up and down is provided. The power supply side terminal 24, the drive coil 25, and the fixed contact plate 26 are each punched out of a separate metal plate having a required thickness dimension, and are bent. Since the thickness and width of the power supply terminal 24, the drive coil 25, and the fixed contact plate 26 can be freely set independently, the ring width of the drive coil 25 is increased to increase the conduction area without increasing the thickness. It can be secured.

Description

Circuit breaker

The present invention relates to a circuit breaker having a drive coil for driving the arc generated between the contact points at the time of interruption toward the arc extinguishing device.

16 shows the basic configuration (first conventional example) of the main portion of this type of conventional circuit breaker. A fixed contact point 2 is provided at one end of the fixed contact plate 1 fixedly installed in a case (not shown), while the fixed contact point is provided at the tip end of the movable arm 3 capable of swinging up and down with a proximal end as a support point. The movable contact 4 which isolates contact with (2) is provided. The fixed contact plate 1 is configured to have the power supply side terminal 5 integrally at the proximal end, and although not shown, the proximal end of the movable arm 3 is connected to the load side terminal via a trip device.

As a result, when an abnormal current such as a short circuit current flows in the path between the power supply terminal 5 and the load terminal, the movable arm 3 is moved upward by the trip device, and the movable contact plate 4 is fixed to the fixed contact (2). ) To open the contact. At this time, the arc generated between the contacts (2, 4) is an arc extinguishing device having a plurality of grid plates (6b) up and down between the two side plates (6a) (only one side) provided with the contact portion sandwiched therebetween. It is segmented by (6) and is to be extinguished. The grid plates 6b are provided with cutouts corresponding to the movement trajectories of the fixed contact plate 1 and the movable arm 3.

Moreover, the drive coil 7 is located between the stationary contact plate 1 and the power supply side terminal 5 on the outside of the arc extinguishing device 6 and is integrally provided. This drive coil 7 is comprised by connecting the inverted U-shaped recess 7a located in the outer surface side of the said both side plates 6a in the lower end part. As a result, the arc is driven toward the extinguishing device 6 by the interaction of the magnetic field generated by the current flowing through the drive coil 7 and the contact (Lorentz force) generated by the contact, and thus the arc is quickly extended. You are lodged.

In recent years, however, miniaturization of the height-direction dimension has been demanded as a circuit breaker of this kind, and attempts have been made for various kinds of miniaturization of the contact portion, the drive coil 7 and the arc extinguishing device 6 described above. In addition, according to such a demand for miniaturization, further improvement of the blocking performance is required, and several attempts have been made.

In such a trial, Japanese Patent Application Laid-Open No. 62-123626 discloses a configuration of the fixed contact plate 1, the drive coil 7 and the power supply terminal 5 (hereinafter, the three contacts are integrated). Second conventional example) and Japanese Patent Application Laid-Open No. 3-25811 (called the third conventional example) are as follows.

17 and 18 show a second conventional example. Here, the elongated rectangular metal plate 8 having the hole 8a as shown in FIG. 17 is bent at the broken line in the drawing. As shown in FIG. 18, the fixed contact 9 which has the fixed contact plate 1, the drive coil 7, and the power supply side terminal 5 integrally is formed. In this case, the drive coil 7 is formed by bending the metal plate 8 in the inverted U shape while shrinking it in the longitudinal direction. According to this, the material yield can be made favorable.

However, in this configuration, the rated current is applied to a large model of, for example, 225AF or more, in order to secure the energization cross-sectional area of the fixed contact plate 1 and the drive coil 7. Since the width must be enlarged, the width | variety of the fixed contactor 9 will be enlarged, and there exists a fault which leads to enlargement of the whole width direction. In order to increase the energizing cross-sectional area, it is also considered to increase the thickness of the metal sheet 8, but this increases the fixed contactor 9 in the height direction and deteriorates the workability of the bending molding.

19 and 20 show a third conventional example. Here, as shown in FIG. 19, the drive coil 7 is unfolded in both the left and right directions to form a metal sheet, and is bent to stand upwards to fix the contactor. (11) (FIG. 20) was formed. According to this, even if the rated current is applied to a large model of 225AF or more, the width of the drive coil 7 can be increased without increasing the overall width. However, when the width dimension of the drive coil 7 is enlarged, the amount which extends to the side of the metal plate 10 becomes large, resulting in deterioration of material yield. In addition, when the thickness of the drive coil 7 is increased, bending molding becomes difficult.

Next, the structure shown in FIG. 21 is disclosed by Unexamined-Japanese-Patent No. 62-163234 (the 4th prior art example) which aimed at the improvement of the breaking performance. In this case, by setting the height position of the drive coil 7 to be equal to or approximately above the position of the movable contact 4 when the movable arm 3 is opened and removed, the arc is moved to the arc extinguishing device 6 side at high speed. It is supposed to be. In this configuration, however, the distance from the fixed contact point 2 of the movable contact point 4 is short, and the initial arc length cannot be large, so that it is not possible to sufficiently improve the breaking performance.

Further, the improvement of the arrangement of the drive coil and the arc extinguishing device is disclosed in Japanese Patent Laid-Open No. 62-123627 (Fifth Conventional Example), which is shown in FIGS. 22 to 24. As shown in FIG. Here, the drive coil 7 is arranged inside the side plate 6a of the arc extinguishing device 6 and the grid plate 6b is provided on the side of the drive coil 7. As a result, the distance in the width direction between the fixed contact point 2 and the drive coil 7 can be reduced, and the overall width dimension can be reduced. However, in this structure, since the extinguishing device 6 must be arranged on the power supply side terminal 5 side, there is a drawback that the enlargement of the longitudinal direction (left and right directions in the drawing) of the device is caused.

As a method of improving the magnetic driving force of the drive coil 7, the configuration shown in Japanese Patent Laid-Open No. 62-123629 (sixth conventional example) or Japanese Patent Laid-Open No. 63-102136 (sixth conventional example) is considered. That is, FIGS. 25 to 32 show a sixth conventional example, of which the inner contacts of the left and right drive coils 7 forming an inverted U-shape in the configurations of FIGS. 25 and 26 show the fixed contact point 2 therebetween. A yoke 12 made of a magnetic material integrally having a pair of fitting portions 12a positioned to be fitted and a connecting portion 12b for connecting them at the lower end portion is provided. According to this, the generated magnetic flux can be concentrated in the vicinity of the stationary contact 2, and the self-driving performance of an arc can be improved.

27 to 29 show a configuration in which the yoke 13 is integrally formed on the grid plate 6b as a modification, and the yoke 14 is shown as another modification in FIGS. The structure which was formed integrally with the grid board 6b is shown. However, such a structure in which the yokes 12 to 14 are provided has a drawback in that the structure becomes complicated and the insulation is difficult to secure.

33 shows a seventh conventional example, in which a yoke 15 made of a magnetic material forming the magnetic field is provided so as to extend over the upper ends of both drive coils 7. In this configuration, however, the self-driving performance of the arc can be improved, but there is a drawback that causes an enlargement in the height direction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a first object thereof is to provide a driving coil between the stationary contact plate and the power supply terminal, which can reduce the width of the driving coil and improve the material yield. To provide a circuit breaker that can be. A second object of the present invention is to provide a circuit breaker capable of improving the breaking performance in addition to the first object.

1 is a perspective view of principal parts showing a first embodiment of the present invention.

2 is a plan view showing the punching shape of the power supply terminal (a), the drive coil (b), and the fixed contact plate (c) from the metal sheet.

3 is a perspective view of a fixed contact.

Figure 4 is a longitudinal front view showing the shape of the magnetic field by the drive coil.

Fig. 5 is a side view showing the main part of the arc at the time of breaking.

6 is a plan view of principal parts showing a second embodiment of the present invention;

7 is a side view of the main part.

8 is a perspective view of principal parts showing a third embodiment of the present invention.

9 is a plan view of the main part.

10 is a side view of the main part.

11 is a plan view of principal parts of a fourth embodiment of the present invention;

12 is a side view of the main part.

13 is a cross-sectional plan view showing the shape of the magnetic flux by the drive coil together with Reference Example (b).

14 is a plan view of principal parts showing a fifth embodiment of the present invention;

Fig. 15 is a main part side view.

Fig. 16 is a perspective view of main parts showing a first conventional example.

17 is an exploded view of a fixed contactor showing a second conventional example.

18 is a perspective view of a fixed contact.

19 is an exploded view of a fixed contactor showing a third conventional example.

20 is a perspective view of a fixed contact.

21 is a cross-sectional side view of a main portion showing a fourth conventional example.

Fig. 22 is a longitudinal sectional side view showing a fifth conventional example.

23 is a main portion longitudinal side view.

24 is a main portion longitudinal side view.

Fig. 25 is a longitudinal sectional side view showing the sixth conventional example.

26 is an exploded perspective view of the main part.

27 is a longitudinal end side view of the main part.

28 is a perspective view of main parts.

29 is a plan view of main parts.

30 is a main longitudinal side view.

31 is a perspective view of main parts.

32 is a plan view of main parts.

33 is a perspective view of principal parts showing a seventh conventional example.

The circuit breaker of claim 1 is provided with a driving coil between the fixed contact plate and the power terminal, and comprises the fixed contact plate, the power supply terminal and the driving coil separately, and the fixed contact plate and There is a feature in the configuration that the power supply terminal is coupled via a driving coil. According to this, the plate | board thickness and width dimension of a drive coil can be set freely regardless of the plate | board thickness of a fixed contact plate, a power supply terminal, etc. In this case, the position of the distal end of the arm of the drive coil may be configured to be substantially intermediate to the opening separation dimension at the time of fully open separation of the movable arm. According to this, in the initial stage of arc generation, the magnetic field of the drive coil can be concentrated in the fixed contact portion.

Moreover, the dimension between both side plates of the said arc extinguishing apparatus can also be comprised so that the part arrange | positioned above the drive coil may become wider than the part arrange | positioned inside the drive coil (invention of Claim 3). According to this, the width dimension of the part arrange | positioned inside the drive coil of an arc extinguishing apparatus can be suppressed small, and the width dimension of a grid board can be enlarged in the part located in the upper part of a drive coil.

In addition, the distance between the fixed contact point and the tip end portion of the grid plate may be 1/2 or more of the distance between the pair of arm portions of the drive coil (Invention 4). According to this, the magnetic field of the drive coil is not dominated by the grid plate, and the magnetic flux driving the arc in the direction of the grid plate can be effectively applied to the arc.

And it is good also as a structure which arrange | positions the board which consists of magnetic materials outside the said drive coil (invention of Claims 5-7). According to this, the effect of the magnetic driving force of the drive coil can be improved.

Hereinafter, various embodiments of the present invention will be described with reference to FIGS. 1 to 15.

Example 1

1 to 5 show a first embodiment of the present invention (corresponding to claim 1).

Although not shown in detail at first, the overall configuration of the circuit breaker according to the present embodiment will be briefly described. This circuit breaker has a fire extinguishing chamber in a case made of an insulating material, for example, at the left end, and is provided by disposing a fixed contactor 21 and a fire extinguishing device 22 in the extinguishing chamber. Moreover, the movable arm 23, the trip device which is not shown in figure, the operation handle, etc. are equipped in the said case (right side of a arc room).

As will be described later in detail with reference to FIGS. 1, 3, and 5, the fixed contactor 21 includes a power supply terminal 24, a driving coil 25, and a fixed contact plate (exposed to the outer surface of the case). It is comprised by combining 26, and the fixed contact 27 is provided in the upper surface of the said fixed contact plate 26. As shown in FIG. On the other hand, the movable arm 23 is provided to be swingable with its proximal end shaft (the right end side in FIG. 5) as a support point, and has a movable contact 28 at the distal end thereof in contact with the fixed contact 27. It is composed. At this time, the tip side of the movable arm 23 penetrates the walls of the arc chamber and is discharged into the arc chamber.

The trip device is provided with an overcurrent drawing device, a toggle link mechanism, or the like as is well known, and the base end of the movable arm 23 is electrically connected to a load side terminal exposed to the outer surface of the case via the overcurrent drawing device. It is. The toggle link mechanism is mechanically connected to the movable arm 23 and is also connected to the operation handle. Therefore, when an abnormal current flows in the main circuit (between the power supply terminal 24 and the load terminal), the overcurrent extractor detects this and activates the toggle link mechanism to move the movable arm 23 in the open separation direction so that the contact is opened. It is. In addition, when the circuit is closed, the movable arm 23 is pressed downward by a spring (not shown) so that the movable arm 23 is pressed against the stationary contact 27 so as to be in contact.

The extinguishing device 22 has a side plate made of an insulating material provided to sandwich both sides of the contact portion (fixed contact 27 and movable contact 28) as shown in FIGS. 29) (only one side is shown for convenience), and it is comprised so that the several sheets of the grid board 30 which consist of magnetic materials may be multiply up and down. In addition, although not shown in detail, each U-shaped cutout part 30a is formed in each grid board 30 from the upper surface so that the movement space of the front end part of the said movable arm 23 may be secured.

The fixed contactor 21 will also be described. As described above, the fixed contactor 21 is provided with a power supply terminal 24, a driving coil 25, and a fixed contact plate 26, but in this embodiment, the power supply terminal 24 and the driving coil 25 are used. And the fixed contact plate 26 is punched out of separate metal plate materials 31, 32 and 33 (see FIG. 2) each having a required thickness and is configured separately.

As shown in FIG. 2 (a), the dual power supply terminal 24 is punched out of the metal plate 31 by a rectangular plate with a slightly narrower proximal side, and as shown in FIG. It is bent and composed. Moreover, the screw hole 24a for a connection is formed in the front end side of this power supply side terminal 24. As shown in FIG.

As shown in FIG. 2 (b), the driving coil 25 is formed by punching out from the metal plate 32 in a shape of a long round ring, and then bending both ends in the longitudinal direction at substantially right angles. As a result, the driving coil 25 has a form in which the left and right pairs of arm portions 25a, which form an inverted U-shape, stand upward, and two connecting portions 25b for connecting these arm portions 25a to the lower ends thereof are integrally formed. Further, the fixed contact plate 26 is punched out of the metal plate member 33 into a small rectangular plate as shown in FIG. 2C, and then bent as shown in FIG. The fixed contact 27 is fixed to the upper surface of the front end of this fixed contact plate 26.

As shown in FIG. 3, the power supply terminal 24 has its proximal end secured with a connecting portion 25b of one side (left side in the drawing) of the drive coil 25 by, for example, soldering or welding. The base end portion of the fixed contact plate 26 is fixed to the upper surface portion of the other connecting portion 25b of the drive coil 25. As a result, the stationary contact plate 26 and the power supply side terminal 24 are coupled via the driving coil 25 to form the stationary contactor 21.

In the assembled state of the movable contact 21 into the case, as shown in FIG. 1, the left and right arm portions 25a of the drive coil 25 are located outside the side plates 29 of the arc extinguishing device 22. have. In this case, the fixed contact 27 is such that the drive coil 25 is located at the center portion.

In the above configuration, when an overcurrent such as a short circuit current flows in the main circuit in the closed state of the contact (see FIG. 5 (a)), the movable arm 23 is moved upward by the trip device as described above, and the contact is opened. As shown in FIGS. 4 and 5 (b), an arc A is generated between the fixed contact 27 and the movable contact 28 according to the open separation of the movable contact 28. At this time, the magnetic field B as shown in FIG. 4 is generated by the rotation of the drive coil 25 by the current flowing through the drive coil 25.

And the movable contact 28 (movable arm 23) separated by the opening is moved to the fully open separation position by the magnetic repulsion force, and the arc A generated at this time is the arc extinguishing device by the Lorentz force which is the interaction of the magnetic field B. It is taxed toward the grid board 30 of (22). As a result, as shown in FIG. 5 (c), the arc A extends rapidly by the grid plate 30, is divided, and rapidly extinguishes.

However, in the above configuration, when applying to a large model having a rated current of, for example, 225AF or more, it is necessary to secure a large energized cross-sectional area of the fixed contact plate 26 and the drive coil 25. In this case, the second conventional example described above (see FIGS. 17 and 18) causes an increase in the width direction of the fixed contact 9, and in the third conventional example (see FIGS. 19 and 20). There is a drawback that leads to deterioration of the material yield.

However, in the present embodiment, the power supply terminal 24, the driving coil 25, and the fixed contact plate 26 are constituted by separate members, respectively, so that the power supply terminal 24, the driving coil 25, and the fixed contact plate 26 are separated. Plate thickness and width dimension can be set freely. Specifically, in the drive coil 25, by increasing the link width, a large conducting cross-sectional area can be ensured without increasing the thickness, and in the fixed contact plate 27, by enlarging the thickness, a large conduction is not required even if the width is increased. The cross-sectional area can be secured.

Therefore, unlike the second conventional example, it is possible to prevent the enlargement of the width direction. On the other hand, as shown in FIG. 2, since the power supply side terminal 24, the driving coil 25, and the fixed contact plate 26 can each be precisely punched in the state of being sandwiched from the metal plate materials 31, 32, and 33, respectively, 3 Unlike the conventional example, the material yield can be improved. Since the power supply side terminal 24 and the drive coil 25 do not have to increase the thickness very much, the bending workability is also excellent.

As a result, according to the present embodiment, the drive coil 25 is provided between the fixed contact plate 26 and the power supply terminal 5, so that the width of the drive coil 25 can be reduced in size. It is possible to obtain an excellent practical effect that can improve the material yield.

Example 2

Next, a second embodiment (corresponding to claim 1) of the present invention will be described with reference to FIGS. 6 and 7. FIG. The present embodiment differs from the first embodiment in that the height position of the tip end of the arm portion 41a of the drive coil 41 is approximately the middle position of the open separation dimension at the time of fully open separation of the movable arm 23. have. In the present embodiment, the drive coil 41 has a configuration in which the pair of arm portions 41a are integrally connected by the connecting portion 41b.

In such a configuration, the arc A generated in the vicinity of the fixed contact 27 at the initial stage of the open separation of the movable arm 23 (movable contact 28) is urged by the drive coil 41 to form a grid. It will be shifted in the direction of the plate 30. In this case, since the arc A is generated near the fixed contact point 27 in the initial stage of the open separation, the arc A can be quickly and efficiently transferred by arranging the drive coil 41 near the fixed contact point. . It goes without saying that the height dimension of the drive coil 41 can be reduced.

Example 3

8 to 10 show a third embodiment (corresponding to claims 1 and 3) of the present invention. The present embodiment differs from the second embodiment in the configuration of the arc extinguishing device 51. In other words, the arc extinguishing device 51 is configured by combining the lower partition 52 and the upper partition 53 such as the upper and lower parts of the arc extinguishing device 22 of the first and second embodiments.

The lower partition body 52 is located inside both arm portions 41a of the drive coil 41, and a plurality of sheets are provided between the side plates 54 and 54 having a height dimension slightly above the arm portions 41. Grid plate 55 is provided. On the other hand, the upper partition 53 is configured by providing a plurality of grid plates 57 between the two side plates 56, 56 located at substantially equal intervals to the width dimension of the drive coil 41. Accordingly, the grid plate 57 is configured to have a slightly larger width dimension than the grid plate 55.

In the upper partition 53, both side plates 56 are respectively wrapped on the upper side of the outer surface side of both side plates 54 of the lower partition 52, and both side plates 56 are upper part of the drive coil 41. It is mounted on the upper part of the lower partition 44 so that the extinguishing device 51 may be comprised. In addition, cutouts 55a and 57a are formed in the grid plates 55 and 57, respectively.

According to such a structure, the width dimension (that is, the width dimension of the drive coil 41) of the lower part split body 52 in which the drive coil 41 is arrange | positioned inside the arc extinguishing apparatus 51 can be restrained small, and the width of the whole is small. In the upper part 53 located above the drive coil 41 while preventing the enlargement of the direction in advance, the width dimension equivalent to that of the drive coil 41 can be set, and the width dimension of the grid plate 57 is increased. can do. As a result, the cooling effect of the entire extinguishing device 51 can be improved, and the breaking performance can be improved.

Example 4

11 to 13 show a fourth embodiment (corresponding to claims 1 to 4) of the present invention. In the present embodiment, the distance M (see FIG. 12) between the fixed contact 27 and the tip end of the grid plate 55 is the distance L between both arm portions 41a of the drive coil 41 (see FIG. 12). The grid plate 55 in the vicinity of the stationary contact 27 is separated to the left side in the drawing so as to be 1/2 or more of the size).

FIG. 13 shows the relationship between the magnetic flux C generated between the two arm portions 41a of the drive coil 41 and the magnetic flux D due to the arc at the time of breaking, and as shown in FIG. 13 (b). Likewise, in the case where the distance between the grid plate 55 and the fixed contact point 27 is short (2M L), the magnetic flux C generated between both arm portions 41a of the drive coil 41 is the magnetic plate of the grid plate 55. ), It becomes difficult to contribute to the driving of the arc (A). On the other hand, in this embodiment, as shown in FIG. 13 (a), the distance between the grid plate 55 and the fixed contact point 27 is increased so that the magnetic flux generated between both arm portions 41a of the drive coil 41 is increased. (C) can be effectively acted on the arc A without being affected by the grid plate 55. As a result, according to this embodiment, the blocking performance can be further improved.

Example 5

Finally, FIGS. 14 and 15 show a fifth embodiment (corresponding to claims 1 to 7) of the present invention. In this embodiment, in addition to the configuration of the fourth embodiment, a plate 61 (referred to as a magnetic plate 61) made of magnetic material, which is located on the outer side of both arm portions 41a of the drive coil 41, is provided. have.

According to this configuration, the magnetic flux generated in the drive coil 41 passes through the magnetic plate 61, thereby preventing the dispersion of the magnetic flux. Therefore, the magnetic flux can be concentrated in the vicinity of the stationary contact 27, and a strong magnetic field can be applied to the arc A. FIG. In addition, the magnetic shield 61 can also obtain a mutual magnetic shielding effect. As a result, according to this embodiment, the blocking performance can be further improved.

As apparent from the above description, according to the present invention, the following excellent effects can be obtained.

That is, according to the circuit breaker of claim 1, a driving coil is provided between the fixed contact plate and the power supply side terminal, and the fixed contact plate, the power supply terminal, and the driving coil are separately formed, respectively, and the fixed contact plate and the power supply side. Since the terminals are coupled through the driving coil, the thickness and width of the driving coil can be set freely regardless of the fixed contact plate or the thickness of the terminal on the power supply side, and the width of the driving coil can be downsized. Material yield can also be improved.

In this case, if the position of the tip of the arm of the drive coil is positioned at approximately the middle of the opening separation dimension at the time of fully open separation of the movable arm, the magnetic field of the drive coil can be concentrated at the fixed contact portion at the beginning of arc generation. This can improve the blocking performance.

Further, if the dimensions between the two side plates of the extinguishing device are configured to have a width wider than that of the part arranged on the inside of the drive coil (circuit breaker of claim 3), the drive coil of the extinguishing device The width dimension of the grid plate can be increased in the portion located above the drive coil while the width dimension of the portion disposed inside is small, and the breaking performance can be improved while meeting the demand for miniaturization. When the distance between the fixed contact point and the grid plate tip is set to be 1/2 or more of the pair of arm portions of the drive coil (circuit breaker of claim 4), the magnetic field of the drive coil is not controlled by the grid plate. As a result, the magnetic field from the drive coil for driving the arc in the direction of the grid plate can be effectively acted on the arc, and the blocking performance can be further improved.

If a plate made of a magnetic material is disposed outside the drive coil (circuit breaker of claim 5), the drive coil can improve the effect of the magnetic driving force, thereby further improving the breaking performance.

Claims (6)

A fixed contact plate having a fixed contact at the tip side and having a power supply terminal at the proximal side, a movable arm having a movable contact separated from the fixed contact at the distal end, and having a proximal end connected to the load side terminal; A plurality of sheets are provided between a trip device for moving the movable arm in the open separation direction to open a contact when an abnormal current flows between the load side terminals, and both side plates provided to sandwich both sides of the fixed contact plate. An arc extinguishing device in which a grid plate is arranged in multiple stages in a moving direction of the movable contact; a pair of arm portions positioned outside the two side plates corresponding to the leading end of the movable arm and extending in a contact separation direction of the movable contact; It has a connecting portion for connecting the arm portion integrally, and has a drive coil for biasing the arc generated between the contact point toward the arc extinguishing device The fixed contact plate, the power supply side terminal, and the driving coil are separately formed, and the fixed contact plate and the power supply terminal are coupled to each other via the driving coil, and the position of the tip portion of the arm of the driving coil. Is a position approximately in the middle of the open separation dimension during full open separation of the movable arm. 2. The circuit breaker according to claim 1, wherein a dimension between the two side plates of the arc extinguishing device is wider than a portion disposed above the drive coil in a portion disposed inside the drive coil. The circuit breaker according to claim 1 or 3, wherein the distance between the fixed contact point and the grid plate is at least 1/2 of the distance between the pair of arm portions of the drive coil. The circuit breaker according to claim 1, wherein a plate made of a magnetic material is disposed outside the drive coil. The circuit breaker according to claim 3, wherein a plate made of a magnetic material is disposed outside the drive coil. The circuit breaker according to claim 4, wherein a plate made of a magnetic material is disposed outside the drive coil.