JPS5828136A - 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 that has improved current-limiting performance at the time of interruption by %.

Figure 81 (a) is a cross-sectional plan view showing a general Fi circuit breaker, and Figure 1 (b) is a line b-bK of Figure 1 (a).
FIG. In FIGS. 1(a) and 1(b), if the movable contact (802) and the fixed contact (202) are now closed, the current flows from the fixed conductor (201) to the rotating contact (202) to the movable contact. Contact (802) - Movable conductor (30
It flows along the route 1).

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 (802
) is separated from the rotating contact (202). At this time, there is an arc A between the fixed contact (202) and the movable contact (802).
occurs, and an arc voltage is generated between the fixed contact (202) and the movable contact (802). This arc voltage increases as the separation distance of the movable contact (802) 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 and the arc A is extinguished, completing the interruption. During such critical operation, the movable contact (802) and the fixed contact (202)
There is a short period of time, that is, several millimeters, between
) A large amount of energy is generated within seconds □ Therefore,
The temperature of the gas inside the enclosure (1) rises, and the pressure also rises rapidly, but this high-temperature, high-pressure gas flows through the outlet (101).
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 (802) will be particularly explained. Generally, arc resistance R is given by the following formula.

That is, R-ρ- where R: arc resistance (cutting ρ: arc resistivity (Ω・31) j!: arc length cm &) S: arc cross-sectional area (-) However, generally at large currents of several KA or more, arc length L
In a short arc A in which the arc is less than 50, 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 heated to high temperature and pressure by being injected with electrical energy. It is electrically conductive and flows away from the conductor at high speed while expanding in a direction that follows the pressure distribution in the arc space. and,
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. The applied force; thus, 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, (802) is a movable contact, and each of the contacts (202) and (802) XIj [i is the contact (202), (802)
) are the opposing surfaces in case of contact, and the contact point (202),
Each Y plane (802) indicates a part of the contact surface and conductor surface other than the opposing surface X plane. 'Also, the rings indicated by the dashed-dot lines in the figure (Z are the contact points (202), (302)
It shows the outer part of the arc A that occurs between the two, and furthermore, the metal particles aj? and metal particles are contacts (202), (802
) is a schematic diagram of each metal particle emitted from the X-plane and Y-plane due to evaporation, etc., and the emission direction is
The direction of each streamline is indicated by the arrows t=pm and n, respectively.

The metal particles a and b emitted from such contacts (202) and (102) rise from the boiling point temperature of a conductive metal, about s, ooo ℃, to the temperature at which they become conductive, that is, s, due to the energy in the arc space. , over ooo℃,
- Or the temperature is raised to an even higher temperature of about 20,000℃, and in the process of temperature rise, energy is removed from the arc space, lowering the temperature of the arc space, resulting in arc resistance R
increase. Note that the amount of energy taken away by the metal particles a and b from the arc space is determined by the temperature of the metal particles at the contact point (202).
Metal particles a emitted from (802).

It is determined by the position of b in the arc space and the emission meridian. However, in the conventional circuit breaker shown in FIG. 2, metal particles a emitted from near the center of the opposing surface
A large amount of energy is removed from the arc space, but the metal particles emitted from the Y-plane of the contact surface and part of the conductor surface remove a smaller amount of 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 and the temperature of the arc space is lowered, thus increasing the arc resistivity ρ, but in the range where the metal particles flow, a large amount of energy is not taken away. To,
The temperature of the arc space decreases little, and therefore the arc resistivity ρ cannot be increased.Moreover, since the arc is generated from the opposing surface X surface and the contact surface also decreases.

Since the outflow of energy from the arc space due to such metal particles is balanced with the electrical injection energy, if the amount of metal particles generated between the contacts injected into the arc space is increased, Naturally, it can be seen that it is possible to greatly reduce the temperature of the arc space, thereby increasing the arc resistivity and greatly increasing the arc voltage.

Furthermore, a major drawback of conventional contact conductors is that the arc foot expands directly to the junction with the conductor, which is often provided on this Y plane, due to the expansion of the arc foot to YrkJ, and this heat causes the melting point There was a risk that the bonding member, which had a low temperature, would melt and cause the contact to fall off.

An object of the present invention is to obtain a circuit breaker which has a high arc voltage, has good current-limiting performance at the time of breaking, and is free from the risk of contacts falling off.

Embodiments of the present invention will be described below based on the drawings. 8th
FIG. 8(a) is a plan sectional view showing one embodiment of the circuit breaker according to the present invention, and FIG. 8(b) is a line b of FIG. 8(a).
It is a side sectional view at -b. Figure 8(a).

In (b), the enclosure (1) is composed of Fi insulator and forms the outer frame of the switchgear, and the outlet (iot)
It is equipped with The fixed contact (2) includes a fixed conductor (201) fixed to the enclosure (1) and a fixed contact (202) attached to one end of the fixed conductor (201). The movable contact (3) opens and closes with respect to the fixed contact (2), and includes a movable conductor (801) which opens and closes with respect to the fixed conductor (201), and a fixed contact (202)'
K is composed of a movable contact (802) attached to one end of a movable conductor (aol) facing each other. The operating machine section (4) opens and closes the movable contact (3).

The arc extinguishing plate (5) has a movable contact (802) and a fixed contact (202).
) is used to extinguish the arc that occurs when the wire is opened. Pressure reflectors (6) and (7) each have extremely small shrinkage rates when molded. j j−,, f k ;
fir a * # H (D0B cost J! ('B pu
”l 'k), each with a fixed contact (20
2) Fixed conductors (201) surround the outer periphery of the movable contact (802) and face the arc A.
), attached to the movable conductor (aOt).

Now, when the movable contact (802) and the fixed contact (202) are closed, the current flows between the fixed conductor (201) and the fixed contact (202).
02)→movable contact (802)→movable conductor (aOt), from the power supply side to the load side. In this state, if a large current such as a short-circuit current flows through this circuit, the operation mechanism section (4
) operates to move the movable contact (802) to the fixed contact (202).
). At this time, an arc A is generated between the fixed contact (202) and the movable contact (802).

In this arc A, as shown in Figure 4, the metal particles are reflected by the pressure reflectors (6) and (7) K, creating a high pressure in the arc space, and as a result, the arc is effectively cooled and extinguished. .

FIG. 4 is a schematic explanatory diagram of the behavior of metal particles in the circuit breaker of FIG. 8. In FIG. 4, (202) and (802) are a pair of opposing contacts, and a fixed conductor (201) surrounds the respective contacts (202), (802) and faces arc A. ), the movable conductor (801) is provided with pressure reflectors (6), (7).

Metal particles between the contacts in such a circuit breaker behave 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, but at least compared to the case where the pressure reflectors (6) and (7) are not provided. It shows an overwhelmingly high value. Therefore, the surrounding space Q with considerably high pressure generated by the pressure reflectors (6) and (7) exerts a force that suppresses the expansion of the space of the arc A, causing the arc A to be "squeezed" into the narrow space K. become. 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, metal particles a emitted from the X plane.

C is 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 incomparably with conventional devices, thereby significantly cooling the arc space. Therefore, the resistivity ρ, that is, the arc resistance R is significantly increased, and the arc voltage is significantly increased.

By the way, in this invention, the pressure reflector (6).

Since (7) is made of polyester BMC, there are the following advantages. In other words, since polyester BMC exhibits a low heat shrinkage rate (molding shrinkage rate), it is suitable for integral molding with metal, and integral molding increases the adhesion reliability.
In addition, since the thermal conductivity effect with the conductor (201) (801) can be improved, the degree of burnout due to arc can be reduced.

The pressure reflector made of polyester BMC is
The temperature rises due to the arc and decomposition gas is generated. This decomposed gas deprives the arc of energy and cools it.

In addition, due to the generation of decomposed gas, the pressure on the surface of the pressure reflector increases, promoting the effect of narrowing the arc, and as the pressure received by the pressure reflector increases, this pressure is applied to the movable conductor, causing the contact to open. You can increase your speed. In this way, the effect unique to the organic material is added to the effect of the pressure reflector alone, making it possible to greatly increase the arc voltage.

Additionally, additives such as water-containing alumina can be easily added to this resin composition. By adjusting t, it is possible to adjust the decomposition gas generated when exposed to the high temperature of the arc and change it back to hydrocarbon gas, improving not only the current limiting performance but also the insulation recovery characteristics at zero current. Therefore, the shutoff performance can be further improved. In addition, when it comes into contact with the arc, the organic composition is vaporized in a state close to sublimation due to the catalytic action of the added water alumina, so there is almost no carbonaceous layer deposited on the surface, and the pressure reflector near the contact point is It has a very high M efficiency, and there is no need to worry about insulation failure or deterioration of the circuit breaker. The legs of A become Ylfi-\ difficult to expand, and generally the contacts (202), (802) and conductors (201), (8) provided on this Y plane
01) has the advantage that it is difficult for the arc foot to directly touch the joint, and as a result there is no risk of the contact falling off.

Figure 5(a) shows the pressure reflector (6), ? Fig. 5(b) is a side view showing another embodiment of 7).
FIG. That is, although the pressure reflectors (6) and (7) shown in the 3rd DA are plate-shaped,
As shown in Figure 5 (a) and Figure 5 (b), the conductor (201
), a pressure reflector (6) to cover the outer periphery of (801)
, (7) may be formed.

Moreover, FIG. 6(a) is a ψ0 plane view showing still another embodiment of the pressure reflectors (6) and (7), and FIG. 6(b) is a plan view of the one in FIG. 6(a). It is. That is, grooves are formed in parts of the pressure reflectors (6), (7) so that the surfaces of the conductors (201), (801) are exposed from one end side of the contacts in the direction away from the contacts (202), (802). (
601) and (701) are provided. Like this
The legs of the arc A run through the arcs (601) and (701), and the arc A touches the arc extinguishing plate (5), where it is cooled and the breaking performance is improved.

FIG. 7(a) is a side view showing still another embodiment of the pressure reflector (G), (7), and FIG. 7(b) is a plan view of the pressure reflector (G), (7). That is, the surface ml of the portions (801) and (901,) of the conductors exposed in the grooves is the same as or more protruding than the surface of the pressure reflectors (6) and (7). With this configuration, the arc person's legs can move quickly, which has the advantage of further improving the breaking performance.

As described above, according to the present invention, it is possible to obtain a safe circuit breaker that has much higher current-limiting performance than conventional circuit breakers and does not cause contacts to fall off.

[Brief explanation of the drawing]

, FIG. 1(a) is a plan view showing a general circuit breaker,
(in Figure 1) is a cross-sectional view taken along line b-1)K in Figure 1 (a), Figure 2 is a schematic illustration of the behavior of metal particles in the circuit breaker in Figure 1, and Figure 8 (a ) is a plan view showing an embodiment of the circuit breaker according to the present invention, FIG. 8(b) Fi
8(a) is a side sectional view taken along line bb, FIG. 4 is a schematic illustration of the behavior of metal particles in the circuit breaker of FIG. 8, and FIG. 5(a) is a pressure reflector and other FIG. 5(b) is a side view showing an embodiment of the pressure reflector, FIG. 6(a) is a side view showing still another embodiment of the pressure reflector, FIG. FIG. 7(a) is a side view showing still another embodiment of the pressure reflector, and FIG. 7(b) is a plan view thereof. (2)... Fixed contact, (201)... Fixed conductor,
(202)... Fixed contact, (3)... Movable contact,
(got)...Movable conductor, (802)...Movable contact, (6), (7)...Pressure reflector O. Note that the same reference numerals in the drawings indicate the same or corresponding parts. Agent Makoto Kuzuno (1 other person) Figure 4C1 (a) (b) Figure 3

Claims (5)

[Claims] (1) At least one pair of electrical contacts consisting of a conductor and a contact fixed to the conductor is provided, and each of the electrical contacts has a pressure reflector mounted on the conductor so as to surround the outer periphery of the contact. However, at least one of the pressure reflectors is made of BMC (Bulk Molding) made of polyester molding material.
A circuit breaker characterized in that it is formed of a compound. (2) The circuit breaker according to claim 1, wherein the pressure reflector is a coating that covers the outer periphery of the conductor. (3) The circuit breaker according to claim 1, wherein the pressure reflector is a plate member attached to the contact side surface of the conductor. (4) At least one of the pressure reflectors has a groove at one end extending from a side surface of the contact and exposing a portion of the conductor in a direction moving away from the contact. The circuit breaker according to item 2 or item 8. (5) The circuit breaker according to claim 4, wherein a part of the surface of the conductor exposed in the groove protrudes to be the same as or more than the surface of the pressure reflector.