JPS5844637A - 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 flow performance during interruption.

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 bb--b of FIG. 1(a). In this figure, (1) is an insulating enclosure that forms the outer frame of the circuit breaker, and is provided with an outlet (101) on the - side wall. (2) is a fixed contact, and a fixed conductor (201) fixed to the above-mentioned enclosure D).

It consists of a fixed contact (202) fixed to the tip of this fixed conductor (201). (3) is the above fixed contact (2)
A movable contact that is paired with a movable conductor (301) driven by the operating mechanism section (4), and a fixed contact (301) fixed to the tip of the movable conductor (301) of the fixed contact (2).
A movable contact (302-) that approaches and separates from the contact point (202-) and a karana tree. (5) is an arc extinguishing plate that cools the arc generated 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 1, the operating mechanism section (4) is activated and the town moving scissors point (
302) 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).
2) An arc voltage is generated between the two. This arc voltage increases by 1 as the separation distance of the movable contact (302) from the fixed contact (202) increases. Moreover, at the same time, the arc voltage further increases as the arc person is attracted by the magnetic force and extends in the direction of the arc extinguishing plate (5).

In this way, the arc current reaches a current zero point, extinguishes the arc, and completes the interruption. During such a breaking operation, the movable contact (302) and the fixed contact (202)
Between them, a large amount of energy is generated by the Ark in a short period of time, that is, within a few seconds.As a result, the temperature of the gas inside the enclosure (1) rises, and the pressure also rises rapidly. However, this high temperature and high pressure gas is released into the atmosphere from the exhaust port (101).

The circuit breaker and its internal components operate as described above when breaking the circuit breaker, but then the fixed contact (2
02) and the movable contact (302) will be particularly explained. Generally, arc resistance R is given by the following formula: In other words,!几=-1 However, mR: Arc resistance (] Partial arc resistivity (Ω・CWl) != Arc length 6IIL) S: Arc cross-sectional area (cd) However, in general, arc length with large current of several KA or more l
In short arcs of less than 50 m, 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, these 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 pressure, and become 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 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, the X plane indicates the opposing plane when the fixed contact (202) and the movable contact (302) come into contact, and the Y plane indicates the 1
A part of the contact surface and conductor surface other than the
02) and the movable contact (302), and a and b are the fixed contacts (202).
, are schematic illustrations of metal particles emitted from the X and Y planes of the movable contact (302) by evaporation, etc., and the emission directions are along the streamlines indicated by arrows m and n, respectively. It is the direction.

Such fixed contacts (202), movable contacts (302)
The metal particles a and b emitted from
The temperature at which it becomes conductive, i.e., s, ooo°C
The temperature is raised to above or even higher, about 20,000"Q, and in the process of temperature rise, energy is removed from the arc space, lowering the temperature of the arc space and increasing the arc resistance. , the amount of energy taken away by the metal particles a and b from the space is greater as the degree of temperature rise of the metal particles increases;
), (302) is determined by the position in the arc space and the emission path of the metal particles a, 'b. However, in the conventional circuit breaker shown in Fig. 2,
Metal particles a emitted from near the center of the X-plane opposite to the flesh take away a large amount of energy from the arc space, but metal particles a from the contact surface and part of the Y-plane of the conductor surface,
Compared to metal particles a, the amount of energy taken away from the arc space is small, that is.

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. However, in the range where the metal particles A are flowed, in order not to take away a large amount of energy, the arc space is m
Therefore, it is not possible to increase the arc resistivity.Furthermore, since the arc is generated from the opposing surface X surface and the contact surface Y surface, the arc cross-sectional area S also increases.
Therefore, arc resistance R also decreases.

Since the outflow of energy from the arc space by such metal particles a and b is balanced with the electrically injected energy, if the contact point (202)' (30
2) If we increase the amount of metal particles generated in the arc space that are injected into the arc space, the temperature of the arc space will naturally decrease significantly, and as a result, the arc resistivity p will increase (and the arc voltage will increase significantly. It turns out that it is possible.

Furthermore, a major drawback of the conventional contactor (!l (+1)
There are six key points: the arc person's foot is likely to expand directly at the junction between the conductor (201) and (3101), and the heat generated at that time will melt the joining material with a low melting point, causing the contact to fall off. .

This invention was made from the above viewpoint, and has at least 41 pairs of contacts each consisting of a conductor and a contact fixed to the contact, and a pressure reflector is attached to each of the conductors so as to surround the outer periphery of each of the contacts. The pressure reflector is composed of a mica molded insulator formed by heating and press-molding mica powder as Al and magnesium oxide powder as a filler with a binder made of low melting point glass powder. In particular, it is an object of the present invention to provide a circuit interrupter that greatly increases the arc voltage, improves the current limiting performance during interruption, and prevents the 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 of FIG. 3(a). be. Figure 3(a), (
In b), the enclosure (
1) is made of an insulator, and has an outlet (lOl) on the side wall.
). The fixed contact (2) is composed of a fixed conductor (201) fixed to the enclosure (1) and a fixed contact (202) attached to the tip of the fixed conductor (201). The movable contact (3) opens and closes with respect to the fixed contact (2), and is attached to the tip of the movable conductor (301) facing the movable conductor (aOl) and the fixed contact (202). It is composed of a movable contact (302). The operating mechanism section (4) opens and closes the movable contact (3). The arc extinguishing plate (5) extinguishes the arc generated when the movable contact (302) 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) include a fixed contact (202) provided thereon, and a movable conductor (301) surrounding the outer periphery of the movable contact (302). A plate-shaped pressure reflector (a) e (7) facing the arc person is attached. Both of the contacts (202).

(302) protrudes from the pressure reflectors (6) and (7), and the pressure reflectors (6) and (7) are made of low-melting glass made of mica powder as a base material and magnesium oxide powder as a filler. The insulator is formed by heat and pressure molding using a binder made of powder.

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, if a large current such as a short circuit current flows through this circuit, the operating mechanism When the part (4) is activated, the movable contact (302
) is separated from the fixed contact (202). At this time, an arc occurs between the fixed contact (202) and the movable contact (302). In Jin's Ark, as shown in Figure 4, metal particles a and c are reflected by the pressure reflectors (6) and (7) K, creating a high pressure in the arc space, and as a result, the Ark is effectively cooled. The arc is extinguished.
- Figure 4 shows the fixed contacts (20
2) and a movable contact (302). FIG. That is, as can be seen from FIG. 4, the contact point (202)? The pressure value in the space Q on the same side of (302) cannot be higher than the pressure value in the space of the arc A itself, but at least the pressure reflector (a),
Compared to the case where (7) is not provided.

It shows an overwhelmingly high value. Therefore, the pressure reflector (6)
, the high pressure on the priest caused by (7) 4′)l
In the one-sided space Q, the expansion of the arc person's space gives a force that suppresses 9, and the arc A is "squeezed" into a narrow space. This means that the metal emitted from the opposing surface, the X plane The streamlines m and o of particles a, C, etc. are compressed and confined in the arc space. Therefore, the metal particles a and c emitted from the X plane are effectively injected into the arc space. As a result, a large amount of effectively injected metal particles a*cti~ 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 is significantly increased, the arc voltage is significantly increased, and the current limiting performance is improved.

In addition, pressure reflectors (6) and (7), arc A
It becomes difficult for the legs to expand to one plane, and generally the contacts (202), (302) and the conductor (
201).

It has the advantage that it is difficult for the arc person's foot to directly touch the joint with the (SOl), and as a result, the contact does not come off.◎ The circuit breaker with the above structure is different from the conventional circuit breaker. Although the pressure reflectors (6) and (7) have significantly superior current-limiting performance compared to the pressure reflectors (6) and (7), the selection of materials is important for this invention. This is an important issue.

As mentioned above, when a large current such as a short circuit current flows through the circuit,
The operating mechanism section (4) operates to separate the movable contact (302) from the fixed contact (202). At this time, contact (3
02) An arc occurs between (202) and the voltage of this arc is increased to obtain extremely good current-limiting performance.The arc heat and pressure reflectors (a) and (7) are configured in the rounding. A large amount of gas is generated from the material surface to cool the arc and at the same time increase the pressure in the arc space between the contacts (AO23, (202)) to help constrict the arc and accelerate the opening speed. Effective.

In addition, when the surface of the material comes into contact with a high-temperature arc, it decomposes or melts. It is also important that the surface resistance does not decrease.If the surface resistance decreases, the arc's legs will continue to expand, and a complete current limiting effect will not be obtained.Furthermore, in this type of breaker, Since the material is repeatedly cut off a large number of times, there is little wear and tear on the material itself due to arcing, and it has a good lifespan and is not damaged by mechanical or thermal shock or strength. is required.

If the wear and tear is large, or if the contact is damaged, no pressure increase can be achieved in the arc space between the contacts (302) and (202), leading to a decrease in the performance of the contact.

As mentioned above, there are a wide variety of conditions that the materials constituting the pressure reflectors (6) and -(y) should meet.

By the way, ore has traditionally been used as an arc-resistant insulating material.

Organic, asbestos, and ceramic materials are often used.

Organic materials generate a large amount of decomposed gas when exposed to the high temperature of the arc, greatly contributing to the cooling or extinguishing effect of the arc, and exhibit extremely excellent current limiting performance. However, they have a low heat resistance temperature and have poor thermal conductivity. Because of bad sex.

In the case of large current interruptions or stationary interruptions, the high temperature of the arc causes deterioration and loss of life, which is a disadvantage in terms of lifespan.
After tit and decomposition gas is generated, carbonaceous decomposition products precipitate, causing problems such as lowering the resistance of the material surface. Asbestos-based materials have structural water in themselves, which causes the high temperature of the arc. When exposed to water, this structural water becomes water vapor gas and is generated in large quantities, so this material is effective in terms of current limiting performance and can cool and extinguish the arc, making it easy to form.
Moreover, since asbestos is made of fiber, it has strong impact resistance and is inexpensive.

However, on the other hand, in the case of severe shutoffs or frequent interruptions, the amount of gas generated is finite, so it gradually decreases from the initial stage, and the current limiting performance deteriorates.
Asbestos thermally decomposes to produce a glassy substance, and at the same time has low surface resistance at high temperatures and defects that cause wear and tear.In addition, asbestos itself has increased hygroscopicity, making it difficult to electrically insulate in humid atmospheres. inferior in sex. Furthermore, asbestos is a hazardous substance designated as a specified chemical substance.

There are major problems in terms of hygiene and pollution, and there are fatal flaws.

On the other hand, ceramic materials are high melting point materials and have a high heat resistance, do not generate thermally conductive materials, and do not have local temperature increases, so they do not wear out or deteriorate significantly. Moreover, since it has the effect of cooling arc heat and increasing arc resistance, it exhibits the same effect as cooling by gas generated from organic and asbestos materials, and has good current limiting performance.

However, due to its low mechanical strength, it has the fatal defect of poor impact resistance, and is subject to thermal shock due to momentary large arc heat, and mechanical shock and vibration due to frequent interruptions of the circuit breaker. Easy to damage.

As mentioned above, in conventional arc-resistant materials.

Since it is not easy to obtain a material that satisfies the characteristics required for a pressure reflector, in this invention, as a result of studying the materials constituting the pressure reflector, mica powder was used as the base material, and mica powder was used as the filler, which is useful for arc resistance. A mica molded insulator made of a mixture of magnesium oxide powder and low-melting glass powder made by melting lead oxide, boric acid, zinc oxide, silicon oxide, etc. as a binder, and molded under heat and pressure using a mold. It was used.

Conventional molded insulators using mica powder and low-melting glass are commonly called K "Micalex" and are used as inorganic heat-resistant insulators, such as brush holders of rotating equipment or insulators for insulated airtight terminals. electrical insulation, mechanical strength, and heat resistance.

It has excellent weather resistance, mechanical workability, and moldability.

However, if Jin's ``Micalex'' is used as an arc-resistant material and exposed to high temperatures of a large arc, it will form a shiny granular vitrified state and the insulation resistance at high temperatures will be extremely reduced. However, there was a problem in that the restriking phenomenon caused the circuit to be disconnected.

Therefore, in this invention, while utilizing the excellent properties of "MICALEX" as an insulator, in order to maintain the arc-resistant properties, we added magnesium oxide powder, which is useful for arc-resistant, as a filler, and used it as an arc-resistant material. It was constructed as a pressure reflector.

This mica molded insulator, which is used as a material, has good current-limiting performance and long lifespan in addition to the excellent properties of "MICALEX", and satisfies the characteristics required for pressure reflectors. , the raw material composition ratio is 10 to 60% mica powder as a base material.
(-superposition ratio, same below) Preferably 15 to so 1
, 5 to 50% magnesium oxide as a filler, preferably 10 to 40%, and 25 to 8% low melting glass as a binder.
ochi, preferably #'i in the range of 30 to 80chi〇In the composition range of the above raw materials, the mica powder that is the base material has good electrical insulation and withstand voltage, and is suitable for pressurization as a flaky material. It forms a layered structure with other raw materials interposed therebetween during molding, serves as a reinforcing material, has a good reaction effect with the glass bonding material, and has good binding properties and water resistance. Therefore, if the ratio is less than 10, the mechanical strength and electrical insulation will be poor, and if it is more than 60, the ratio of other fillers will be low.
The arc resistance will be poor.

Magnesium oxide powder, which is a filler, is a high melting point substance that has high resistance at high temperatures and excellent arc resistance.
If it is less than 51%, there will be little effect on electric arc resistance, and if it is more than 50%, the blending ratio of the base material will be reduced, resulting in poor mechanical strength and dielectric strength, and the material will be hard, resulting in poor machinability.

Low melting glass as a binder generally has a melting point of about 350-45
It shows a dislocation point near 0°C, melts at 500 to 900°C, and has good reactivity with the mica powder of the base material.

It completely binds fillers, etc. In addition, since it is glassy, it has good water resistance, moisture resistance, and excellent weather resistance. However, if it is less than $C2591, the flow and mobility during molding will be poor, and there will be problems with moldability, and other raw materials will not be able to be firmly bound. In addition, mechanical strength and arc resistance properties become poor.

The insulating material constituting the pressure reflector used in the present invention will be specifically explained below.

37 pieces of synthetic mica powder with a particle size of 60 to 200 mesh as a base material, and fused magnesium oxide with a particle size of 6 as a filler.
30% powder of 0-100 mesh, PbO as binder
= o, 7 mol, ZnO = 0.3 mol, B, 0.
= 0.5 mol.

A mixture soy prepared by preparing and mixing 33 pieces of low melting point glass powder with a composition ratio of s:o, ==o, a mole and a particle size of 20G mesh or less is prepared as a raw material. This raw material has an inner diameter of 98 mm.
Fill the mold of X981111 and apply pressure 300
Cold pressure molding is performed at #/d to create a preform. Next, this preform was heated in a heating furnace at 850°C for 15 minutes, and then attached to a separate press platen.
It was filled into a mold with an inner diameter of 100 u x 100 M kept at 430°C, heated and pressure molded at a pressure of 700 Q/c11, and after the pressure was maintained for 3 minutes, the mold was removed to obtain a molded insulator. .

When exposed to the high temperature of the arc, the damage was extremely slight, with only a slight dullness forming in the center of the arc, and the current limiting performance was also good.

Similarly, 35 pieces of natural phlogopite powder with a particle size of 48 to 12G mesh were insulated by the above-mentioned molding method in 909, which had a composition ratio of 10% magnesium oxide powder - SS powder of low melting point glass. When a glass body was created and used as a pressure reflector, a glass with a slightly glossy finish was produced due to the strong arc, but the current limiting performance was good, there were no phenomena such as consumption, wear, or breakage, and the surface resistance was reduced. There was none.

As described above, mica molded insulators made of mica powder and low-melting point glass powder mixed with magnesium oxide as a filler can be used even when exposed to high temperatures of a large arc.
Eutectic fusion between mica powder and glass prevents vitrification and changes to crystalline material, resulting in extremely high resistance at high temperatures.KL has the effect of extinguishing the arc by increasing arc impedance and increasing arc voltage. be.

However, if glass precipitates on the highly arcuate surface, fine particles of molten metal such as those at the contact point will scatter and adhere to the surface of the pressure reflector during breaking, reducing the resistance of the highly arcuate surface or The oxide is dissolved to further lower the vitreous viscosity and the insulation resistance, but if the highly arcuate surface is crystalline, there will be less adhesion of scattered metal particles, so there will be no melting.

Therefore, the resistance at high temperatures does not decrease and there is no need to worry about restriking or short circuits.

In addition, the above-mentioned insulators have a laminated layer of flaky material on the base material and use mica powder that also serves as a reinforcing material, so they have high thermal and mechanical impact resistance and do not have problems such as breakage. , it also has high withstand voltage. Also, since glass is used as a binder, it has low water absorption and excellent weather resistance and insulation properties. Furthermore, it has the characteristics of good molding, particularly accurate dimensional accuracy, and good mechanical workability.

As the mica powder, in addition to synthetic mica and natural mica, natural muscovite can be used to obtain the same characteristics.

Furthermore, in addition to electrolytic magnesium oxide, sintered and combustible magnesium oxides are also effective, but electrolytic magnesium oxide is difficult to use due to its reaction with the binder during hot-pressure molding and the density of the product. Optimal.

As mentioned above, by using a mica-manufactured insulator made by heating and press-molding a mixture of mica powder as the base material, magnesium oxide powder as the filler, and low-melting point glass powder as the binder, current-limiting performance has been achieved. - It is possible to provide a pressure reflector having excellent properties such as arc resistance such as lifespan, impact resistance, electrical insulation, voltage resistance, weather resistance, and mechanical workability.

Fig. 5(a) is a side view showing another embodiment of the above-mentioned contacts (2) and (3); ), (3) is a plan view. That is, the pressure reflector (6>,
(7) is a plate-like material provided only on the contact side surfaces of the conductors (202) and (302), but Fig. 5 (Jl) l
As shown in (b), there are 20 fixed conductors and 3 movable conductors.
The pressure reflectors (6) and (y) may be formed by covering the periphery of the pressure reflectors (6) and (y) with tubing or coating.

FIG. 6(a) is a side view showing another embodiment of the contactor (21, (1)), and FIG.
) is a plan view of the contacts (2) and (31) shown in FIG. A groove (601) in which the surfaces of the fixed conductor (201) and the movable conductor (SOl) are exposed in the direction away from the outlet (101) from the side surface.

(701) is provided. ? In the configuration -, the arc person's feet run through the grooves (6o1) and (yot), and the arc person touches the arc extinguishing plate (5) and is cooled, thereby improving the breaking performance.

Furthermore, Fig. 7(a) is a side view showing another embodiment of the a contactor (27, (3)), and Fig. 7(b) is a side view showing another embodiment of the a contactor (27,
FIG. 3 is a plan view of the contactor (21, (3)) shown in FIG.

In other words, (!101).

As shown in (901), the groove (6o1) in FIG.
(701)・ The conductor surface exposed from the pressure reflector (6
), -(7) is raised higher than the surface. With this configuration, the legs of the arc A can be moved quickly, and there is an advantage that the breaking performance is improved.

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

[Brief explanation of the drawing]

FIG. 1(a) is a partially cutaway plan view showing a general circuit interrupter, FIG. 1(b) is a sectional view taken along line bb of FIG. 1(a),
FIG. 2 is a schematic explanatory diagram of the behavior of metal particles in the circuit breaker of FIG. 1, and FIG. 3(a) is a partially cutaway plan view showing an embodiment of the circuit breaker according to the present invention. Figure 3 (
b) is a sectional view taken along the line b-b of Fig. 3(a), Fig. 4 is a schematic explanatory diagram of the behavior of metal particles in the circuit breaker of Fig. 3, and Fig. 5(a) is a cross-sectional view taken along the line b-b of Fig. 3(a). Fig. 6(a) is a side view showing another embodiment of the contactor, and Fig. 6(a) is a side view showing another embodiment of the contactor. Figure 6(b) is a top view of the contact shown in Figure 6(a).
FIG. 7(a) is a side view showing another embodiment of the contact, and FIG. 7(a) is a plan view of the contact shown in FIG. 7(a). (2)... Fixed contact, (201)... Fixed conductor,
(202) °・Fixed contact, (3)... Movable contact, (301)... Movable conductor, (302) = - Movable contact, (6), (7)... Pressure reflector, (
601). (701)... Groove Note that the same reference numerals in the drawings indicate the same or corresponding parts. Agent Makoto Kuzuno - (1 other person) Figure 1 (a) Figure 1 (b) Figure 2 Figure 4 Unexamined Patent Publication I] A58-4463 (Length 5) Figure 3 (a) / Figure Figure 31(b)

Claims (1)

[Scope of Claims] (1) It has at least one pair of contacts consisting of a conductor and a contact fixed thereto, and a pressure reflector is provided on each of the conductors so as to surround the outer periphery of each of the contacts, and the The pressure reflector is characterized in that it is composed of a mica molded insulator formed by heating and press-molding mica powder as a base material and magnesium oxide powder as a filler using a binder made of low melting point glass powder. circuit breaker. (The circuit breaker according to claim 1, wherein the 2J pressure reflector is a plate-like member provided only on the contact side surface of the conductor. (3) The pressure reflector is a coating that covers the periphery of the conductor. A circuit breaker according to claim 1. (4) At least one pressure reflector has one end 11 of a contact point.
The circuit breaker according to claim 1, 2 or 3, wherein a groove is provided so that the surface of the conductor is exposed as the surface moves further away from the 11th surface. (s) Place the exposed conductor surface on the pressure reflector #! The circuit interrupter according to claim 4, which has a raised surface and a raised surface.