CN1113029A - Inturruptor for sub-line - Google Patents

Abstract

A circuit breaker for wiring, provided with a rectangular magnetic body surrounding a closed magnetic circuit of a movable contact and a fixed contact, the movable contact is assembled on the front end of the movable contact, and the fixed contact is assembled on the front end of the conductor of the fixed contact , the fixed contacts are made of conductors that are bent into a U shape and face each other to become two sides. Since the magnetic flux generated in the space on both sides where the fixed contact is sandwiched passes through the magnetic body, the magnetic flux density between the movable contact and the fixed contact, that is, the space where the arc is generated, becomes larger, so the repulsive force F _M of the movable part and the arc The driving force F _A becomes larger, and the arc extinguishing ability is improved.

Description

The present invention relates to a circuit breaker for wiring provided for blocking overcurrent of a circuit, and particularly relates to a magnetic structure provided on the switch part of the contact in order to improve arc extinguishing capability.

Circuit breakers also include circuit breakers for wiring. Its important task is to block large currents such as short-circuit currents to protect circuits. Various methods have been thought of to reliably block larger currents.

Fig. 13 is a front view showing a contact switching unit of a conventional circuit breaker for distribution, and Fig. 14 is a view seen from the arrow direction F thereof. In these figures, the contact opening and closing part is composed of the following parts: the movable contact 12 driven by the driving mechanism not shown in the figure and the movable contact 11 installed at the front end of the movable part 1; A fixed part 2 composed of a fixed contact 22 and a fixed contact 21 installed on the front end of one side; a U-shaped magnetic body 3 that surrounds the space where the movable contact 11 and the fixed contact 21 are located and opens downward; and ensures that the magnetic The body 3 is insulated from the fixed part 2 and the movable part 1 and is used to protect the insulating plate 4 of the magnetic body 3 because an arc is generated between the movable contact 11 and the fixed contact 21 when disconnected. Since the magnetic body 3 needs to surround the driving range of the movable contact 12, it has a shape elongated in the vertical direction. The position represented by the solid line of the movable part 1 is in the "closed" state where the movable contact 11 is in contact with the fixed contact 21, and the position represented by the double-dot lock line in Fig. 1 is in the "open" state.

The current I flowing in the movable part 1 and the fixed part 2 flows in the direction indicated by the arrow in the figure. The fixed contact 22 is made into a U-shape so as to generate a repulsive force to the movable part 1 . That is to say, if the two sides of the U font of the fixed contact 21 equipped with the fixed contact 22 are conductor 221 and conductor 222 respectively, the direction of the current flowing in these conductors 221 and 222 becomes the opposite direction as shown in the figure , the current of the movable contact 12 is opposite to that of the conductor 221 closer to it. A repulsive force to disengage from the fixed contact 22 is thus generated on the movable contact 12 . This repulsion is called moving part repulsion. The purpose of setting the magnetic body 3 is to apply a large electromagnetic force to the arc generated between the movable contact 11 and the fixed contact 21 when the circuit is open, so as to easily extinguish the arc. The electromagnetic force generated by the arc is called is the arc driving force. That is to say, as follows, by means of the current flowing in the movable contact 12 and the fixed contact 22, a magnetic flux is generated in a direction perpendicular to the paper surface of FIG. The magnetic circuit reduces the consumption of the magnetomotive force outside the space where the arc is generated, so that a large magnetic flux can be generated in the space where the arc is generated. If the magnetic flux density at the position where the arc has been generated is denoted as B, and the length of the arc is denoted as L, then the arc driving force F _A is expressed in the following formula.

F _A = IBL

Table 1

Since the magnetic flux density B is proportional to the current I, ignoring the nonlinearity of the magnetic properties of the magnetic body 3, the final arc driving force F _A is proportional to the square of the current I. The above-mentioned repulsive force F _M of the moving parts is also proportional to the square of the current I. Therefore, the arc driving force F _A and the repulsion force F _M of the movable part, which contribute to the improvement of its arc extinguishing ability, have the characteristics of increasing with the increase of current.

Fig. 15 is a magnetic field distribution diagram of a contact opening and closing part of the circuit breaker for distribution shown in Figs. 13 and 14 . The magnitude of the current I flowing in the movable contact 12, the conductor 221 and the conductor 222 is equal, and the direction can be seen from FIG. The curves represent lines of force whose density is proportional to the magnetic flux density. That is to say, the denser the lines of magnetic force, the greater the magnetic flux density B at that position. The movable contact 11 and the fixed contact 21 are not shown in this figure. The position where the arc occurs is between the movable contact 12 and the conductor 221. It can be seen from the figure that the magnetic flux density B is large in this part where the magnetic force lines are concentrated. Most of the lines of magnetic force in this part pass through the magnetic body 3 . Therefore, the magnetic flux density in this part becomes large due to the presence of the magnetic body 3 .

Fig. 16 is a front view showing a contact opening and closing part of a conventional distribution circuit breaker having a different magnetic body shape than the above, and Fig. 17 is a view of Fig. 16 viewed from the direction of the arrow. In these figures, the fixed member 2 and the movable member 1 are the same as the above-mentioned conventional examples, the difference being that the magnetic body 3G has a U-shape opening upward. Since the U-shaped bridging portion is disposed in the space between the conductor 221 and the conductor 222, that is, at a position close to the space between the movable contact 12 and the conductor 221 as an arc generation space, as shown in the figure, the magnetic body 3G Compared with the above-mentioned magnetic body 3, the dimension in the up-down direction can be made much smaller.

Fig. 18 is a magnetic field distribution diagram of a contact opening and closing part of the circuit breaker for distribution shown in Figs. 16 and 17 . As in the case of FIG. 15 , most of the magnetic flux passing through the arc generating space, that is, the space between the movable contact 12 and the conductor 221 passes through the magnetic body 3G, and the magnetic flux density in this portion increases due to the magnetic body 3G.

The shape of the magnetic body is made into a U-shaped opening downward like the magnetic body 3 of FIG. 15 , or it is made into a U-shaped opening upward like the magnetic body 3G of FIG. In addition to the difference in the vertical dimension as described above, the magnitude relationship between the arc driving force F _A and the movable part repulsion F _M is also different in the two magnetic bodies having different shapes. That is, the magnetic body 3 in FIG. 15 has a larger movable member repulsive force _FM and a smaller arc driving force _FA than the magnetic body 3G in FIG. 18 as can be seen from Table 1 below. Therefore, such a difference in the magnitude of the electromagnetic force should also be taken into consideration when selecting the shape and arrangement of the magnetic body.

字形。这样一来，当磁性体3向下开口时，在导体221和导体222之间产生的磁通对使电弧产生空间的磁通密度增大的贡献小，而在磁性体3G向上开口时，与此相反，则在活动部件1上方空间产生的磁通没有有效的贡献。As mentioned above, the magnetic body used in the contact opening and closing part of the existing wiring circuit breaker is made

glyph. Thus, when the magnetic body 3 opens downward, the magnetic flux generated between the conductor 221 and the conductor 222 contributes little to increasing the magnetic flux density in the arc generating space, but when the magnetic body 3G opens upward, the On the contrary, the magnetic flux generated in the space above the movable part 1 has no effective contribution.

The object of the present invention is to provide a circuit breaker for wiring which can simultaneously increase the arc driving force _FA and the repulsive force _FM of the movable part and improve the arc extinguishing capability in order to solve such problems.

In order to solve the above-mentioned problems, the circuit breaker for wiring of the present invention is equipped with: a U-shaped fixed contact, a fixed contact arranged on the front end of one side of the fixed contact, a movable contact driven by a driving mechanism, and a movable contact arranged at an The movable contact on the front end of the side connected to the driving mechanism of the movable contact, when the circuit breaker is closed, the fixed contact and the movable contact are in contact. Road magnets. The magnetic body is rectangular, and can be formed by the openings of two U-shaped magnetic bodies facing each other. The two front ends are arranged overlapping each other, or the protruding parts facing each other are arranged at the position where the movable contact is inserted inside the closed magnetic circuit.

In the structure of the present invention, by arranging a magnetic body forming a closed magnetic circuit surrounding the fixed contact and the movable contact, one side of the conductors on both sides of the U shape that constitutes the fixed contact is equipped with a fixed contact. The magnetic flux generated in the space passes through the magnetic body, so the magnetic flux density in the arc-generating space where these magnetic fluxes pass concentratedly becomes large. The magnetic body forming the closed magnetic circuit can adopt a rectangular parallelepiped and a magnetic body with small reluctance, and can also form a closed loop by disposing two U-shaped magnetic bodies opposite to each other in its opening. At this time, if the two front ends are mutually If two U-shaped magnetic bodies are arranged at predetermined intervals, even if the dimensional viscosity of the two U-shaped magnetic bodies deteriorates, there is no great hindrance to production. By arranging two U-shaped magnetic bodies so that their two front ends overlap each other, it is possible to obtain a magnetic body having a magnetic resistance as small as that of the above-mentioned rectangular magnetic body. The magnetic flux passing between the protrusions can be increased by arranging the mutually facing protrusions at positions where the movable contact is sandwiched inside the rectangle.

Fig. 1 is a front view showing a contact opening and closing unit of a first embodiment of a circuit breaker for distribution according to the present invention.

Fig. 2 is a view seen from the direction of arrow A in Fig. 1 .

FIG. 3 is a diagram showing the magnetic field distribution of the contact switch shown in FIG. 2 .

Fig. 4 is a perspective view omitting the contact opening and closing part of the magnetic body in Figs. 1 and 2 .

Fig. 5 is a front view showing a contact switching unit of a circuit breaker for distribution according to a second embodiment of the present invention.

FIG. 6 is a view seen from the arrow B direction of FIG. 5 .

Fig. 7 is a front view showing a contact switching unit of a circuit breaker for distribution according to a third embodiment of the present invention.

FIG. 8 is a view seen from the arrow C direction of FIG. 7 .

Fig. 9 is a front view showing a contact switching unit of a circuit breaker for distribution according to a fourth embodiment of the present invention.

FIG. 10 is a view seen from the arrow D direction of FIG. 9 .

Fig. 11 is a front view showing a contact switching unit of a distribution circuit breaker according to a fifth embodiment of the present invention.

FIG. 12 is a view seen from the arrow E direction of FIG. 11 .

Fig. 13 is a front view of a contact switching unit of a conventional circuit breaker for distribution.

FIG. 14 is a view seen from the arrow F direction of FIG. 13 .

Fig. 15 is a diagram showing the magnetic field distribution of the contact opening and closing part shown in Fig. 14 .

Fig. 16 is a front view of a conventional circuit breaker for distribution different from that of Fig. 13 .

FIG. 17 is a view seen from the arrow G direction of FIG. 16 .

Fig. 18 is a diagram showing the magnetic field distribution of the contact opening and closing part shown in Fig. 17 .

The present invention will be described below according to the examples. Fig. 1 is the front view of the contact switching part of the wiring circuit breaker of the embodiment of the present invention, and Fig. 2 is the view seen from the direction of arrow A in Fig. 1, and the structural parts identical with Fig. 13, 14 are denoted by the same numerals, Similar structural components are indicated by adding a letter A after the label, and will not be described in detail.

In these figures, the magnetic body 3A is formed in a rectangular shape as shown in FIG. 2 so that it is arranged to surround the conductor 221 of the movable contact 12 and the fixed contact 22, forming a closed magnetic circuit as a magnetic circuit. The combination of the insulator 4 and the magnetic body 3A is also formed into a rectangle, and is arranged inside the magnetic body 3A. Usually the insulator 4 is disconnected at the conductor 221 portion. Movable contact 12 and conductor 221 pass through in the encirclement of magnetic body 3A, because the electric current I flowing on movable contact 12 and conductor 221 is equal in magnitude and direction is opposite, so the summation of the magnetomotive force along the rectangular side of magnetic body 3A is Zero, so there is no magnetic flux component circulating along the closed magnetic circuit of the magnetic body 3A. Therefore, even a closed magnetic circuit has no effect.

Fig. 3 is a magnetic field distribution diagram of the contact opening and closing part shown in Fig. 1 and Fig. 2 . Comparing this figure with the aforementioned Figures 15 and 18, it can be seen that the magnetic flux generated in the space above the movable contact 12 is similar to that of Figure 15, and the magnetic flux generated between the conductor 221 and conductor 222 is similar to that of Figure 18. The individual magnetic fluxes in the space between the contact 12 and the conductor 221 merge together. Therefore, the magnetic flux density B in the arc generating space is larger than either of the above two prior art examples.

Fig. 4 is a perspective view of a contact opening and closing section omitting a magnetic body. A state is shown in which the movable contact 11 is separated from the fixed contact 21 in order to interrupt the current, and an arc 200 that electrically connects the two contacts 11 and 21 occurs at this time. The current I flows in from the right side of the conductor 221 , flows through the fixed contact 21 , the arc 200 , the movable contact 11 , and the movable contact 12 in sequence, and then flows out from the right side of the movable contact 12 . The currents flowing in opposite directions in the movable contact 12 and the conductor 221 generate mutually repulsive electromagnetic force, which is the repulsive force F _M of the movable part, which is an upward force as shown in the figure. These currents generate magnetic flux in the space where the arc 200 is generated, and as a result of the electromagnetic interaction between this magnetic flux and the current I flowing through the arc 200, an arc driving force F _A is generated in the direction shown in the figure.

Calculate the repulsive force F _M of the movable part according to the calculation result of the magnetic field, and integrate the product of the current density i flowing in the cross section of the movable contact 12 and the magnetic flux density B at the position in the entire cross section of the movable contact 12 . Since the current and magnetic flux are AC and have the same phase, they can be calculated simply by using effective value or peak value. The arc driving force F _A is to integrate the product of the current I along the set arc 200 and the component perpendicular to the direction of the magnetic flux density and the current I. At this time, when the direction of the magnetic flux density is different, due to the arc 200 The direction of the force of each part is not the same, so it is necessary to integrate the vector.

Table 1 is a comparison table of the arc driving force _FA and the repulsive force _FM of the movable part under the condition that only the magnetic bodies are different. Taking the case of no magnetic body as a reference value, the magnetic body 3 in FIG. 15 , the magnetic body 3G in FIG. 18 , and the magnetic body 3A in FIG. 3 were compared. The calculation conditions are stipulated as follows: current I=20KA, the gap length between the fixed contact 21 and the movable contact 22 is 3 mm, etc. Also, the lengths of the movable contact 12 and the conductors 221 and 222 are limited, and are approximately infinite for convenience in calculation. Therefore, the numerical values in this table only show the tendency of magnitude relationship, and since the numerical accuracy is not high, more detailed calculation conditions such as the dimensions of the components are omitted.

The values in the table are: the numbers outside the brackets represent each force in Newton (N), and the numbers in the brackets represent the ratio when the value without a magnet is taken as 100.

From this table, it can be seen that, in the case of Fig. 15 and Fig. 18 as a conventional example, the arc driving force F _A and the repulsion force F _M of the movable part are both increased by 10-20% in the case of Fig. 18 compared with the case of no magnetic body. This is the effect of setting the magnetic body 3 or 3G. Comparing the values in Fig. 15 with those in Fig. 18, the arc driving force F _A in Fig. 18 is large, and the repulsion force F _M of the movable part in Fig. 15 is large.

Comparing the values in Fig. 3 with the values in Fig. 15 and Fig. 18, it can be seen that the arc driving force _FA is the same as the value in Fig. 18, and the repulsive force F _M of the movable part is larger than any previous examples.

Fig. 5 is the front view of the contact opening and closing part of the second embodiment of the present invention, and Fig. 6 is a view seen from the arrow B direction in Fig. 5, and the same structural parts as Fig. 1 and Fig. 2 are represented by the same numerals, and similar structural parts are in The letter B is added after the label to replace the original label A, and will not be described in detail. Compared with the magnetic body 3A in FIG. 1 , the magnetic body 3B has a smaller width dimension in FIG. Since the smaller the width, the smaller the increase of the magnetic flux, and after the two contacts 11, 21 protrude, the magnetic flux density in the space where the arc is generated becomes smaller, so the final contact opening and closing parts in Fig. 5 and Fig. 6 are the same as Fig. 1 and Fig. 2 Compared with the contact opening and closing part, the repulsive force F _M of the moving parts and the driving force F _A of the arc are both smaller. However, the magnetic body 3B is smaller in size and lighter in weight than the magnetic body 3A, and thus has an advantage of low cost. Therefore, the appropriate size of the magnetic body can be adopted under the premise of obtaining the necessary repulsive force F _M of the moving parts and the driving force F _A of the arc.

Fig. 7 is the front view of the contact opening and closing part of the third embodiment of the present invention, and Fig. 8 is the view seen from the direction of arrow C in Fig. 7, and the parts with the same structure as Fig. 1 and Fig. 2 are represented by the same symbols, and similar structural parts The letter C is added after the label to replace the original letter A, and will not be described in detail. In these figures, the magnetic body 3C is divided into upper and lower parts of an upper magnetic body 3C ₁ and a lower magnetic body 3C ₂ . The upper magnetic body _3C1 is in a U-shape opening downward, and the lower magnetic body _3C2 is in a U-shape opening upward. Their front ends are opposite to each other with an appropriate gap, and an insulator 4C is provided inside them. The size of the gap can be determined according to the ease of operation such as loading the magnetic body 3C. Since the size of this gap has little influence on the magnetic flux passing through the magnetic body 3C, a structure having such a gap can be employed.

Like the magnetic bodies 3A, 3B, when the magnetic body is made into a single rectangle, there are situations such as difficulty in manufacture and difficulty in incorporating into the contact opening and closing part. In such a case, by dividing the magnetic body into upper and lower parts and providing an appropriate gap, it is possible to facilitate the production and assembly of the magnetic body.

Fig. 9 is a front view of the contact switching part of the circuit breaker for wiring according to the fourth embodiment of the present invention, and Fig. 10 is a view seen from the direction of arrow D in Fig. 9, and the same structural components as Fig. 7 and Fig. 8 are denoted by the same reference numerals Indicates that for similar structural components, the letter D is added after the label to replace the original letter C, and will not be described in detail. In these figures, the magnetic body 3D is composed of a font-shaped upper magnetic body 3D1 opening downward and a U-shaped lower magnetic body 3D2 opening upward, which is the same as the magnetic body 3C of the third embodiment of Fig. 7 and Fig. 8 . The point is to overlap and join the front ends of the upper magnetic body 3D1 and the lower magnetic body 3D2. That is, the upper magnetic body 3D1 is assembled so that the lower magnetic body 3D2 is embedded. Therefore, since there is no gap in the closed magnetic path of the magnetic body 3D like the magnetic body 3C, its magnetic resistance has a value equivalent to that of the magnetic body 3A of the first embodiment. Therefore, when the structure divided into upper and lower parts is applied because the magnetic resistance is expected to be as small as required and due to manufacturing reasons, the magnetic body 3D can be used.

Fig. 11 is a front view of a circuit breaker for wiring according to the fifth embodiment of the present invention, and Fig. 12 is a view viewed from the direction of arrow E in Fig. 11, and the same structural components as those in Fig. 1 and Fig. 2 are denoted by the same symbols, and similar structural components The letter E is added after the label to replace the original letter A, without further elaboration. In these figures, a protrusion 3E1 is provided on the magnetic body 3E, and the protrusion 3E1 protrudes from both sides toward a position where the movable contact 12 is interposed therebetween. This position is a space where an arc is generated, and the magnetic flux passing through the magnetic body 3E exits from the protruding portion 3E1. That is, the magnetic flux passes between the protrusions 3E1 on both sides. Since the length of the gap in this portion is shortened by providing the protruding portion 3E1 , the magnetic flux concentrates between the protruding portions 3E1 on both sides, and the magnetic flux density B increases. This increases the arc driving force _FA .

The magnetic body 3E is formed by providing the protrusion 3E1 on the magnetic body 3A of the first embodiment. Since the protruding portion 3E1 has nothing to do with the structure of the magnetic body before the protruding portion 3E1 is provided, the same effect as that of the magnetic body 3E can be obtained by providing the protruding portion 3E1 on each of the magnetic bodies 3B, 3C, and 3D in the second to fourth embodiments. .

As mentioned above, the present invention is provided with a magnetic body forming a closed magnetic circuit surrounding the movable contact and the fixed contact, and the fixed contact is arranged on one side of the U-shaped conductors on both sides of the fixed contact. The magnetic flux generated in the space on both sides of the conductor passes through the magnetic body, so the magnetic flux density in the space between the fixed contact and the movable contact can be increased, and the repulsive force F _M of the movable part and the driving force of the arc can be increased. Both F _{and A} are also increased, thereby obtaining an effect of improving the arc extinguishing capability.

And, as the magnetic body that forms closed circuit, can adopt the magnetic body of rectangular shape and magnetic resistance small, also can adopt two U-shaped magnetisms, make its opening portion opposite arrangement to form closed circuit, at that time, if two U-shaped magnetic If the two front ends of the magnetic body are arranged at a predetermined distance from each other, even if the dimensional accuracy of the two U-shaped magnetic bodies is not high, it will not affect the production much. Also, by arranging the two front ends of the two U-shaped magnetic bodies overlapping each other, it is also possible to obtain a magnetic body having the same magnitude of reluctance as the above-mentioned rectangular magnetic body. In addition, by arranging the protruding parts facing each other at the position where the movable contact is clamped inside the rectangle, the magnetic flux passing between the protruding parts can also be increased, and then the repulsive force F _M of the movable part and the arc driving force F _A can be obtained. Increased, the arc extinguishing ability improves such an effect.

Claims (6)

1. A circuit breaker for wiring, which has: a U-shaped fixed contact and a fixed contact provided on the front end of one side of the fixed contact, a movable contact driven by a driving mechanism and a fixed contact arranged at a position different from this The driving mechanism of the movable contact connects the movable contact on the front end of that side, and the fixed contact contacts the movable contact when the circuit breaker is closed. body. 2. The circuit breaker for wiring according to claim 1, wherein the magnetic body has a rectangular shape. 3. The circuit breaker for wiring according to claim 1, wherein said magnetic body is composed of two U-shaped magnetic bodies with openings facing each other. 4. The circuit breaker for wiring according to claim 3, wherein said two U-shaped magnetic bodies are provided with a predetermined distance between the two front ends thereof. 5. The circuit breaker for wiring according to claim 3, wherein said two U-shaped magnetic bodies are arranged so that their two front ends overlap each other. 6. The circuit breaker for distribution according to any one of claims 1 to 5, wherein protruding portions facing each other are provided at positions where the movable contacts are sandwiched inside the closed magnetic circuit.

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