JPS60143541A - 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 [Technical Field of the Invention] The present invention relates to a circuit breaker, and more particularly to a circuit breaker with improved current-limiting performance during interruption.

[Prior Art] FIG. 1(a) is a sectional plan view showing a general circuit breaker, and FIG. 1(b) is a side sectional view taken along line bb in FIG. 1(a). In Fig. 1(a) and (b), if the movable contact (302) and the fixed contact (202) are now closed, the current flows from the fixed conductor (201) to the fixed contact (202).
2) Flows through the path of → movable contact (302) → movable conductor (301).

In this state, when a large current such as a short-circuit current flows through this circuit, the operating mechanism section (4) operates and the movable contact (30
2) is separated from the fixed contact (202).

At this time, an arc A is generated between the fixed contact (202) and the movable contact (302), and the arc A is generated between the fixed contact (202) and the movable contact (302).
302), an arc voltage is generated between the two. This arc voltage increases as the separation distance of the movable contact (302) from the fixed contact (202) increases. At the same time, the arc A is attracted and expanded by the magnetic force in the direction of the arc extinguishing plate (5), so the arc voltage further increases -FM.

In this way, the arc current reaches a current zero point and the arc A is extinguished, completing the interruption. During such a cutoff operation, the movable contact (302) and the fixed contact (2Q2
), a large amount of energy is generated by the arc A in a short period of time, ie, within a few milliseconds. Therefore, the temperature of the gas inside the enclosure (1) rises, and the pressure also rises rapidly, but this high-temperature, high-pressure gas is
1) is released into the atmosphere.

The circuit breaker and its internal components operate as described above when breaking the circuit breaker, but then the fixed contact (20
2) and the operation of the movable contact (302) will be explained in detail. Generally, arc resistance R is given by the following formula. That is, R = ρ・S/S However, R: Arc resistance (Ω) ρ: Arc resistivity (ΩΦcI11) S: Arc length Cl11) S: Arc cross-sectional area (G) However, in general, large currents of several KA or more In the case of a short arc A in which the arc length Ω is 50 mm or less, the arc space is occupied by metal particles. Moreover, this release of metal particles occurs at the contact point (202), (
203) occurs in a direction perpendicular to the surface. Also,
At the time of release, these ejected metal particles have a temperature close to the boiling point of the contact metal, and as soon as they are injected into the arc space, they are injected with electrical energy and become high temperature and pressure, and are conductive. It flows away from the conductor at high speed while expanding in a direction according to the pressure distribution in the arc space. The arc resistivity ρ and arc cross-sectional area S in the arc space are determined by the amount of metal particles generated and the direction in which they are released. Therefore, the arc voltage is also determined by the behavior of the metal particles. Next, the behavior of such metal particles will be explained using FIG. 2.

In Fig. 2, (202) is a fixed contact, (302) is a movable contact, and contacts (202), (302)
The respective X planes of are the contact points (202) and (302)
is the opposing surface in contact with, and the Y surface is the surface of the contact point (202), (302) other than the opposing surface X surface and the conductor (
2Ql) , a part of the surface of (202) is shown. In addition, in the figure, the contour Z indicated by the dashed line is the contact point (202), (30
2) Shows the outline of the arc A that occurs between the metal particles a and the contact points (202) and (302)
) (7) This is a schematic diagram of each metal particle emitted from the X-plane and Y-plane by evaporation, etc., and the emission direction is in the direction of each streamline indicated by arrow m and arrow n, respectively. be.

The metal particles a and b released from such contacts (202) and (302) are heated from about 3,000°C, which is the temperature of the conductive metal, due to the energy of the arc space.
The temperature is raised to a temperature at which it becomes conductive, that is, 8,000°C or higher, or a high temperature of about 20,000°C, and in the process of temperature rise, energy is removed from the arc space, lowering the temperature of the arc space, and as a result. , increases the arc resistance R. Note that the amount of energy taken away by the metal particles a and b from the arc space increases as the degree of temperature rise of the metal particles increases, and the degree of temperature rise increases between the points of contact (202) and (302).
It is determined by the position in the arc space and the emission path of the metal particles a and b generated from the arc.

However, in the conventional circuit breaker shown in Fig. 2, the metal particles a emitted from the center of the X plane take away a large amount of energy from the arc space, but the metal particles emitted from the seventh side In comparison, the amount of energy 4 taken away from the arc space is small.

In other words, in the range where metal particles A flow, a large amount of energy is taken away and the temperature of the arc space is lowered, so the arc resistivity ρ increases.On the other hand, in the range where metal particles A flow, a large amount of energy is absorbed and the temperature of the arc space is lowered. Since the temperature of the arc space is not reduced, the arc resistivity ρ does not increase. Moreover, the metal particles from the seven sides increase the cross-sectional area of the arc A, resulting in a decrease in the arc resistance R.

Since the outflow of energy from the arc space by the metal particles a and b is balanced with the electrically injected energy, if between the contacts (202), (30
If metal particles a and b are concentrated in 2), the temperature of the arc space will naturally be greatly reduced, and as a result, the arc resistivity ρ
It can be seen that it is possible to greatly increase the arc voltage by increasing .

Furthermore, a major drawback of conventional circuit breakers is that, due to the expansion of the legs of arc A to Contact point (202) with a low melting point due to this heat
, (302) were at risk of melting and falling off.

[Summary of the Invention] This invention has been made to solve the above-mentioned conventional drawbacks, and provides a circuit breaker that has a high arc voltage, has good current limiting performance at the time of breaker, and does not cause the contacts to fall off. The purpose is to provide equipment.

A feature of this invention is that the surface of the conductor is coated with an electrically insulating layer made of a thermosetting resin containing high-strength inorganic fibers.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 3(a) and (b), the fixed conductor (201)
, and the surfaces of the movable conductor (301) are coated with electrically insulating layers (203) and (303) made of, for example, a thermosetting resin containing high-strength inorganic fibers, respectively. -1- As the thermosetting resin, for example, a thermosetting resin such as a polyester resin or an epoxy resin containing glass fibers or alumina fibers is used. - The fixed conductor (201) and the movable conductor (301) are made of continuous drawn steel, prepared alloy rod, whose entire surface is coated with thermosetting resin.
Alternatively, it is formed by cutting and molding a copper plate material. In addition, a fixed conductor (201) and a movable conductor (301)
) has an electrically insulating layer (203) as shown in FIG.
, the fourth part (204) with part of (303) removed
, (304) are formed respectively, and four parts (2
04), (304), a fixed contact (202) and a movable contact (202), (302) are fixed by brazing or welding.

Now, the movable contact (302) shown in FIGS. 3(a) and (b)
When the fixed contact (202) is closed, the current flows from the fixed conductor (201) to the fixed contact (202) to the movable contact (30
2)→Flows from the power supply side to the movable conductor (301), from the power supply side to the load side. In this state, when a large current such as a short-circuit current flows through this circuit, the operating mechanism section (4) is actuated to separate the movable contact (302) from the fixed contact (202). At this time, an arc A is generated between the fixed contact (202) and the movable contact (302). In this arc A, as shown in FIG. 4, electrical insulating layers (203), (303)
The metal particles a and C are reflected by the arc, the arc space becomes high pressure, and as a result, the arc A is effectively cooled and extinguished.

The reason why the arc is effectively cooled in this way is as follows.

That is, the pressure value in the space Q cannot be higher than the pressure value in the space of the arc A itself, but at least, compared to the case where the electrical insulating layers (203) and (303) are provided, It shows an overwhelmingly high value. Therefore, the surrounding space Q with a considerably high pressure created by the electrically insulating layers (203), (303) provides a force that suppresses the spatial spread of the arc A, "squeezing" the arc A into a narrow space. become. This means that the streamlines m and o of the metal particles a and c emitted from the X plane, which is the opposing surface, are squeezed into the arc space and confined. Therefore, the metal particles a and c emitted from the X plane are effectively injected into the arc space. As a result, most of the effectively injected metal particles a, c significantly cool the arc space because they take away a large amount of energy from the arc space. Therefore, the resistivity ρ, that is, the arc resistance R is significantly increased, and the arc voltage is greatly increased.

Note that in the above configuration, the fixed conductor (201) and the movable conductor (301) are formed by a continuous drawing method using a bar material whose surface is coated with thermosetting resin, so that the fixed conductor (201) and the movable conductor (301) are formed by a continuous drawing method using a bar material whose surface is coated with thermosetting resin. Insulating layers (203) and (303) are easily formed. Moreover, the electrical insulating layers (203), (3
03) is made of thermosetting resin such as polyester resin or epoxy resin containing high-strength inorganic fibers such as glass fiber or alumina m-fiber, so the electrical contact itself has high heat resistance and high insulation properties. That will happen.

In addition, it is conventionally known to have an arc reflector (not shown) made of an insulating material attached to the conductor surface around the contact, but in such a case, the number of parts is reduced by the arc reflector. In addition, if the arc reflector is insufficiently fixed to the conductor, it may fall off, and if the arc reflector is heavy, the opening speed becomes slow. There were drawbacks such as reduced current limiting performance.

However, in the embodiment mentioned above, the electrical insulating layer (203),
(303) is firmly formed on the fixed and movable conductors (20+) and (301) J- by drawing and forming, so it is inexpensive and lightweight, and the opening speed is fast. Current limiting performance does not deteriorate, and the electrical insulating layers (203) and (303) themselves do not fall off.

In addition, since the phase of arc A is difficult to expand to the Y plane, generally the contacts (202) and (3
02) and the conductors (201) and (301), it becomes difficult for the foot of the arc A to directly touch the joint between the contact point (2) and the conductor (201) and (301).
02)', (302) has the advantage of eliminating the risk of falling off.

FIG. 5 is a perspective view showing another embodiment, and shows an electrically insulating layer (
A portion of the conductive surface of the conductor (201) provided with the contact point (203) is exposed in the direction away from the contact point (202), and a convex portion (205) is provided on the conductive surface of the conductor (201). As a result, the legs of the arc run on the convex part (205), and the arc runs on the arc extinguishing plate (5).
) (see FIG. 3(b)) and is cooled, the breaking performance is improved and wear and tear on the contact (202) can be reduced.

[Effects of the Invention] As described above, according to the present invention, by providing an electrical insulating layer made of thermosetting resin on the surface of the conductor, the arc can be focused between the contacts, so that current limiting is achieved. It is possible to provide a circuit breaker with improved performance, heat resistance, and high insulation properties.

[Brief explanation of the drawing]

Figure 1(a) is a plan view showing a conventional circuit breaker;
Figure (b) is a cross-sectional view taken along line bb in Figure 1 (a), Figure 2 is a schematic explanatory diagram of the behavior of metal particles in the circuit breaker in Figure 1, Figure 3 (a) 3(b) is a side sectional view taken along line 2 bb in FIG. 3(a), and FIG. 4 is a plan view showing one embodiment of the circuit breaker according to the present invention. FIG. 5 is a perspective view showing another embodiment of the present invention. (2) - Fixed electrical contact, (3) Movable electrical contact, (201) Fist fixed conductor, (202) Fist fixed contact, (203) (303) Fist electricity insulation layer,
(204), (304)・Fist・Concave, (301)・
・・Movable conductor, (302)・Φ・Movable contact, (305)
...convex part. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent: Masuo Oiwa Procedural amendment (voluntary) Mr. Commissioner of the Japan Patent Office 1. Case description: Japanese Patent Application No. 58-250189 2. Name of the invention: circuit breaker 3. Relationship with the person making the amendment: Patent applicant address: Tokyo 2-2-3 Marunouchi, Chiyoda-ku, Miyako
(601,) Mitsubishi Electric Corporation Representative Hitoshi Katayama 4, Agent 5, Subject of amendment (l J!4/j# Page 4

Claims (1)

[Scope of Claims] (1) A circuit breaker that opens and closes and has at least one pair of electrical contacts each consisting of a conductor and a contact, wherein the surface of the conductor is coated with a high-strength inorganic fiber. A circuit breaker characterized by being coated with an electrically insulating layer made of a curable resin. (2) The circuit breaker according to claim 1, wherein the high-strength inorganic fiber is made of glass fiber. (3) The circuit breaker according to claim 1, wherein the high-strength inorganic fiber is made of alumina fiber. (4) The conductor is formed of continuous drawn steel, copper alloy wire, or copper plate material whose entire surface is continuously coated with thermosetting resin. circuit breaker. (5) The circuit breaker according to claim 1, wherein the connection point is fixed to the conductor in the four parts cut out from a part of the electrical insulating layer. (8) The circuit breaker according to claim 1, wherein the electrical insulating layer is removed from at least one of the conductors in a direction away from the contact to expose the conductor surface. (7) The circuit breaker according to claim 5, wherein the exposed conductor surface is flush with or raised from the surface of the electrical insulating layer.