JPS5828148A - 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 The present invention relates to a circuit breaker, and more particularly to a circuit breaker with improved current-limiting performance during circuit breaker.

FIG. 1(a) is a partially cutaway plan view showing a general circuit breaker, and FIG. 1(b) is a sectional view taken along the line Ob-b of FIG. 1(a). In this figure, (1) is an insulating enclosure that forms the outer frame of the circuit breaker, and is equipped with an outlet (101) on the negative side wall. (2) is a fixed contact, which is fixed to the enclosure (1) and includes a fixed conductor (201) and a fixed contact (201) fixed to the tip of the fixed conductor (201).
202). (3) is a movable contact that forms a pair with the fixed contact (2), and is fixed to the movable conductor (301) driven by the operating mechanism section (4) and the tip of this movable conductor (301). and a movable contact θ0■ that approaches and separates from the fixed contact (202). (5) is an arc extinguishing plate,
It cools the arc A that occurs when the movable contact (302) separates from the fixed contact (202).

Now, when the movable contact (302) and the fixed contact (202) are closed, the current flows from the fixed conductor (201) to the fixed contact (
202)→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) is activated and the movable contact 002
) is separated from the fixed contact (202). At this time, an arc is generated between the fixed contact (202) and the movable contact (302), and an arc voltage is generated between the fixed contact (202) and the movable contact (302). This arc voltage increases as the separation distance of the movable contact (302) from the fixed contact (202) increases. Moreover, at the same time, the arc A is attracted and expanded in the direction of the arc-extinguishing plate (5) by the magnetic force, so that the arc voltage further increases.

In this way, the arc current reaches a current zero point, extinguishes the arc, and completes the interruption. During such critical operation, the movable contact (302) and the fixed contact (202)
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 and pressure of the gas within the enclosure (1) rises rapidly, and this high-temperature, high-pressure gas is discharged into the atmosphere through the exhaust port (101).

The circuit breaker and its internal components operate as described above when breaking the circuit breaker, but the operations of the fixed contact (202) and the movable contact 0o2 will be specifically explained next. Generally, arc resistance R is given by the following formula. That is, R=p-0, where R: arc resistance (Ω) P: arc resistivity (Ω, 3) Il: arc length 3 S: arc cross-sectional area Cd> However, generally at a large current of several KA or more, arc length l
When the arc is short, i.e., 50111 or less, the arc space is occupied by metal particles. Moreover, this release of metal particles occurs in a direction perpendicular to the contact surface. In addition, the ejected metal particles have a temperature close to the boiling point of the metal at the contact point at the time of ejection, and as soon as they are injected into the arc space, they are injected with electrical energy and become high temperature and high pressure. conductive,
It expands in a direction according to the pressure distribution in the arc space and flows away from the conductor at high speed.

The arc resistivity ρ and the arc cross-sectional area si 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 these metal particles. Next, the behavior of such metal particles will be explained using FIG. 2.

In FIG. 2, the X-plane shows the opposing surface when the fixed contact (202) and the movable contact (302) come into contact, and the Y-plane shows a part of the contact surface and the conductor surface other than the above-mentioned X-plane. In addition, the ring z shown by the dashed-dotted line in the figure is a fixed contact (20
2) and the outer arc of the arc generated between the movable contact (302). Furthermore, a and b are fixed contacts (202)
, schematically shows metal particles emitted by evaporation from the X-plane and Y-plane of the movable contact (302), and the emission direction is in the direction of each streamline indicated by arrow m and arrow n, respectively. There are 2 such fixed contacts (202), movable contacts (30)
The metal particles a and b released from
The temperature at which it becomes conductive is approximately 8.000 m.
℃ or higher, or even higher to about 20,000°C, and in the process of temperature rise, energy 7 is taken away from the arc space, lowering the temperature of the arc space, and as a result increasing the arc resistance R. . Metal particles a from the arc space,
The amount of energy removed by 'b increases as the temperature of the metal particle increases;
), (302) is determined by the position in the arc space and the release path of the metal particles a and b emitted from the metal particles a and b.

However, in the conventional circuit interrupter shown in Fig. 2, the metal particles a emitted from near the center of the opposing surface, the X-plane, take away a large amount of energy from the arc space, but the metal particles on the contact surface and the conductor surface The metal particles A, which are partially emitted from the Y plane, take away less energy from the arc space than the metal particles A. In other words, in the range where the metal particles A flow, a large amount of energy is taken away to lower the temperature of the arc space, thus increasing the arc resistivity P, but in the range where the metal particles A flow, in order not to take away a large amount of energy, , the temperature of the arc space decreases little, and therefore the arc resistivity ρ cannot be increased.Furthermore, since the arc A is generated from the opposing surface X surface and the contact surface Y surface, the arc cross-sectional area e also increases. Therefore, the arc resistance R also decreases.

Since the outflow of energy from the arc space by such metal particles a and b matches the electrically injected energy, if the contact points (202), (302
) If the amount of metal particles generated between
As a result, it is found that it is possible to increase the arc voltage by increasing the arc resistivity P.

Furthermore, a major drawback of the conventional contacts (2), (3) is that due to the expansion of the arcuate foot into the Y plane, the contacts (202), (3) are generally often provided on this Y plane.
02) and the conductors (201) and (301), and there was a risk that the heat at that time would melt the joining material with a low melting point and cause the contact to fall off. be.

This invention has been made from the above point of view, and has a pair of contacts consisting of a conductor and a contact fixed to the conductor, and the pressure is reflected on each of the conductors so as to surround the outer periphery of each of the contacts. By providing a body and at least one of the pressure reflectors made of steel with a nitride layer formed on the surface, the arc voltage can be greatly increased and the current limiting performance during interruption can be improved. The object of the present invention is to provide a circuit breaker that can prevent contacts from falling off.

Embodiments of the present invention will be described below based on the drawings.

FIG. 3(a) is a partially cutaway plan view showing an embodiment of the circuit breaker according to the present invention, and FIG. 3('b) is a sectional view taken along line bb--b of FIG. 3(a). It is. Figure 3(a),
In (1)), the enclosure (1) forming the outer frame of the circuit breaker is made of an insulator, and the outlet α is provided on the -side wall.
01). Fixed contact (2) is an enclosure (1)
A fixed conductor (201) fixed to the
01) and a fixed contact (202) attached to the tip. The movable contact (3) is a fixed contact (
2), which opens and closes with respect to the movable conductor (301),
It consists of a movable contact (302) attached to the tip of a movable conductor (301) opposite to a fixed contact (202). The operating mechanism section (4) opens and closes the movable contact (3). The arc extinguishing plate (5) extinguishes the arc that occurs when the movable contact (30) separates from the fixed contact (202).

The fixed conductor (201) of the fixed contact (2) and the movable conductor (301) of the movable contact (3) have fixed contacts (202) and movable contacts (302) provided on them. Plate-shaped pressure reflectors (6) and (7) are attached to surround and face the arc A.

Both the contacts (202) and (302) protrude from the pressure reflectors (6) and (7), and
) and (7) are made of steel with a nitride layer formed on its surface (tuftride treatment).

Note that the arc-extinguishing plate (5) does not have to be used, but it is more effective to use it. The arc-extinguishing plate (5) is made of magnetic or non-magnetic material, but if a non-magnetic arc-extinguishing plate is used,
Circuit breakers with high ratings have had problems with temperature rise during rated operation, and eddy currents caused by magnetic materials were a major cause of this problem, but this problem can be eliminated.

Now, in FIG. 3, when the movable contact (302) and the fixed contact (202) are closed, the current flows through the fixed conductor (202).
1) - Fixed contact (202) -> Movable contact (302) - Movable conductor (301), flowing 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 activated and the movable contact σ02
) is separated from the fixed contact (202). this.

At this time, an arc is generated between the fixed contact (202) and the movable contact 00. In this arc, as shown in Figure 4, the metal particles a and c are reflected by the pressure reflectors (6) and (7), creating a high pressure in the arc space; as a result, the arc is effectively cooled and extinguished. arced.

Figure 4 shows the fixed contacts (20
2) and a movable contact (302). FIG. That is, as can be seen from Fig. 4, the surrounding space q of the contact points (202) and (302)
The pressure value at the arc A cannot be greater than the pressure value in the space of the arc A itself, but at least the pressure reflector (6)
, shows an overwhelmingly higher value than the case where (7) is not provided. Therefore, the pressure reflector (6), (
The surrounding space q, which has a considerably high pressure caused by n, is
The expansion of the space of arc A gives the force to suppress shi, and arc
ft. You will be "squeezed" into a narrow space. In other words, the streamlines m, o of metal particles a, c, etc. 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, the large amount of effectively injected metal particles a, c removes a large amount of energy from the arc space, which is incomparable with conventional devices, and significantly cools the arc space. As a result, the arc resistivity P, that is, the arc resistance R increases significantly, the arc voltage increases significantly, and high current limiting performance is obtained.

Furthermore, since the material of the pressure reflectors (6) and (7) is steel with a nitride layer formed on one surface (tuftride treatment), the surface portions of the pressure reflectors (6) and (7) are inorganic. Because of the nitride layer of tC, it exhibits high resistance, so the legs of arc A are not formed other than at the contact points (202) and (302), and the tC nitride layer and the base steel have high heat resistance. , a pressure reflector exposed to arcum (
a) It is advantageous for (7). In addition, pressure reflectors (
Since the base material of 6) and (7) is steel, it has good heat conduction, and the heat on the surface of the pressure reflectors (6) and (7) is quickly transferred to the inside of the conductors (201) and (301), reducing pressure. Abrasion due to temperature rise on the surfaces of the reflectors (6) and (7) can be suppressed to a minimum. Further, the temperature coefficient of resistance of the base metal steel is large, and when exposed to the arc A, its resistance value increases. Therefore, even if the surface nitride layer is torn, arcum legs will not be formed except at the contact points (202) and (302). Further, even when exposed to arc A, no harmful gas is generated from the nitride layer at the contacts (202) and (302), and there is no effect (corrosion) on the surfaces of the contacts C02) and (302). In addition, the nitride layer on the surface is generated by the diffusion of nitrogen into the base material, and has good adhesion to the base material, so the pressure reflectors (6) and (7) can withstand thermal shock well. . Further, the base material steel has magnetism, and therefore can strengthen the magnetic flux that drives the arc A toward the discharge port (101), or suppress unnecessary magnetic flux by having a magnetic shielding effect. In addition, the base material steel has good demoldability and bendability, and the pressure reflectors (e) and (7) can be easily obtained. In addition, the steel base material is strong, and when attached with caulking or screws, the attachment is strong and reliable. Furthermore, a pressure reflector (6).

Due to (7), the leg of arc A is difficult to expand to the Y plane, and the contact point (202) is generally provided on this Y plane.

(302) and the conductors (201), (301) are difficult to touch directly with the legs of the arc A, and as a result, there is no risk of the contacts (202), (302) falling off. It has points.

FIG. 5(a) is a side view showing another embodiment of the contacts (2) and (3), and FIG. 5(1)) is a side view of the contacts (2) and (3) shown in FIG. 50. (3) is a plan view. That is, some of the pressure reflectors (6) and (7) have contact points (
The conductor (202) and (302) are connected in a direction away from the discharge port (101) with one end side as a base point.
Grooves (601) and (701) are provided such that the surfaces of 01) and (301) are exposed. In this configuration, the legs of the arcum are grooved (601), (
701), the arc A touches the arc extinguishing plate (5) and is cooled, improving the breaking performance.

Furthermore, as shown in Fig. 5, grooves (601) and (701
) The exposed conductor surface is covered with a pressure reflector (6), (
It can be raised to the same level or higher than the surface of 7).

Figure 6 (-) shows the contact (2) with the raised structure.
), (3) is a side view showing the embodiment of FIG. 6 (1).
) are the contacts (2) and (3) shown in Figure 6 (-).
FIG.

That is, as shown by (801) and (901), the surfaces of the conductors (201) and C301) exposed from the grooves (601) and (701) are similar to the surfaces of the pressure reflectors (6) and (7). Shi is also prominent.

With this configuration, Arcum's feet can quickly move to the outlet (
101) side, the breaking performance is improved and the wear of the contacts (202) and (302) is reduced.

As can be seen from the above description, according to the present invention, it is possible to provide a circuit breaker that can greatly increase the arc voltage, improve the light limiting performance at the time of interruption, and prevent the contacts from falling off.

[Brief explanation of the drawing]

Figure 1 (-) is a partially cutaway plan view showing a general front seam breaker, Figure 1 (1)) is a sectional view taken along the b-yb line of Figure 1 (&), and Figure 2 is a cross-sectional view of the FIG. 3(a) is a partially cutaway plan view showing one embodiment of the circuit breaker according to the present invention, and FIG. 3(b) is a schematic illustration of the behavior of metal particles in the circuit breaker shown in FIG. 4 is a schematic explanatory diagram of the behavior of metal particles in the circuit breaker of FIG. 3, and FIG. 5 e) shows another embodiment of the contact. Side view,
FIG. 5(1)) is a plan view of the contact shown in FIG. 5(a), FIG. 6(a) is a side view showing another embodiment of the contact,
FIG. 6(1)) is a plan view of the contact shown in FIG. 6(a). (2)... Fixed contact, (201)... Fixed conductor,
(202)... Fixed contact, (3)... Movable contact,
(301)...Movable conductor, (30...Movable contacts, (6), (7)...Pressure reflector, (6ON)
(701)... Groove Note that the same reference numerals in the drawings indicate the same or corresponding parts. Agent Makoto Kuzuno - (1 other person) Male 1 Figure (a) (b) Figure 52 ＼ No. 3-1 (b) (b) @ Figure 6 (b)

Claims (3)

[Claims] (1) For a pair of contacts consisting of a conductor and a contact fixed thereto, a pressure reflector is provided on each of the conductors so as to surround the outer periphery of each of the contacts, and at least one of the pressure reflectors is A circuit breaker characterized in that it is made of round steel with a nitride layer formed on its surface. (2) The circuit breaker according to claim 1, wherein at least one pressure reflector ve' is provided with a groove such that the surface of the conductor is exposed in a direction moving away from one end side surface of the contact point. (3) The circuit breaker according to claim 2, wherein the exposed conductor surface is raised to the same level or higher than the pressure reflector surface.