JP2000030576A - Rotary arc type gas-blast circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-blast circuit breaker preventing the damage of a moving arc contact and the arcing at a moving main contact and having excellent cutoff performance and high reliability. SOLUTION: This circuit breaker is provided with a main circuit container 1 made of an insulator, a fixed terminal 2 fitted to it, a fixed arc contact 3 fitted to the fixed terminal 2, a drive coil 8, a fixed main contact piece 9 fitted to the fixed terminal 2, and a moving electrode 12 contactably/separably supporting the fixed arc contact 3 and the fixed main contact piece 9. A moving arc contact 12c provided at the tip of the moving electrode 12 is made of graphite, an intermediate conductor 12d is provided between the base section 12a of the moving electrode 12 and the moving arc contact 12c, the inherent electric resistance value of the intermediate conductor 12d is set to a value between the electric resistance values of the graphite and the base section 12a of the moving electrode 12, and the intermediate conductor 12d and the moving arc contact 12c are coupled to form a coupling section 12h.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas circuit breaker, and more particularly to a structure of a movable electrode of a rotary arc type gas circuit breaker in which an arc is rotated and extinguished by a magnetic field generated by flowing a breaking current through a driving coil. It is about.

[0002]

2. Description of the Related Art As a conventional gas circuit breaker, for example, there is one having a structure as shown in FIG. FIG. 4 is a side sectional view showing an open state of the rotary arc type gas circuit breaker. In the figure, 1 is a main circuit container made of an insulating material, and 2 is a fixed terminal as an external terminal, which is attached to the main circuit container 1.
3 is a fixed arc contact attached to the fixed terminal,
4 and 5 are attached and pressurized toward the center. Reference numeral 6 denotes an arc-extinguishing cylinder, which has an arc runner 7 serving as a foot of the arc and a driving coil 8 for driving the arc mounted on and fixed to the fixed terminal 2. A fixed main contact 9 is concentrically arranged on the outer periphery of the arc-extinguishing cylinder 6 and is pressed toward the center by springs 10 and 11. Reference numeral 12 denotes a movable electrode, which has a movable main contact 12b and a movable arc contact 12c on a base 12a, and moves up and down on a central axis to come into contact with and separate from the fixed arc contact 3 and the fixed main contact 9. The circuit is opened and closed. This rotary arc type gas circuit breaker operates as follows. When the movable electrode 12 in the closed state is urged downward by a mechanism (not shown), the movable main contact 12b is separated from the fixed main contact 9, and then the movable arc contact 12c is separated from the fixed arc contact 3.
Then, an arc is generated between the fixed arc contact 3 and the movable arc contact 12c. As the movable electrode 12 moves downward, the arc moves from between the fixed arc contact 3 and the movable arc contact 12c to between the arc runner 7 and the movable arc contact 12c,
A magnetic field is generated by a cut-off current flowing through a drive coil 8 electrically connected between the arcrunner 7 and the fixed terminal 2, and the arc is rotated and driven to cool and extinguish at a current zero point.

[0003]

However, the conventional gas circuit breaker has the following problems. That is, since the movable arc contact 12c uses an arc-resistant metal, for example, a copper tungsten alloy,
Local evaporation of copper in copper-tungsten alloy occurs violently, polluting the arc space with a large amount of metal vapor,
Tungsten that has lost copper, which is a copper-tungsten alloy joint, easily falls off, forming a projection on the movable arc contact 12c and causing electric field concentration, resulting in a problem that insulation breakdown occurs and interruption becomes impossible. . In addition, when the entire movable arc contact 12c is made of graphite, there are the following problems. (1) When a large current is interrupted, a current is shunted to the fixed arc contacts 3 and flows in the same direction. Further, when the movable arc contact 12c and the fixed arc contact 3 are separated from each other, a large current arc is generated, and the temperature of the movable arc contact 12c serving as a foot of the arc becomes high. As a result, the mechanical impact force and the thermal impact are continuously applied to the graphite of the movable arc contact 12c, so that the graphite is broken and cannot be cut off. (2) Graphite has a specific electric resistance at the base of the movable electrode 12
If (12a) is, for example, copper, it is very high, about 1000 times as large as this. For this reason, when the large current is interrupted, the movable main contact 12b is separated from the fixed main contact 9, and when the entire current is commutated to the fixed arc contact 3, the current is commutated because the electric resistance of the movable arc contact 12c is high. It becomes difficult, and the movable main contact 12b and the fixed main contact 9
Sparks occur between them. As a result, the movable main contact 12
The contact resistance between b and the fixed main contact 9 increases, causing abnormal heat generation. Further, there is a danger that the energization of the movable main contact 12b may occur or the main circuit container 1 may be destroyed. (3) In addition, since the difference in electrical resistance between the graphite and the movable electrode 12 is large, a large current flow during the interruption causes a transient arc at the boundary between the graphite and the movable electrode 12, and metal vapor is generated from the movable electrode 12. Generates and contaminates the arc space.
As a result, the dielectric strength between the contacts decreases, and the breaking performance decreases. SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary arc gas circuit breaker which is excellent in breaking performance without damaging a movable arc contact or firing at a movable main contact.

[0004]

In order to achieve the above object, the present invention provides a main circuit container (1) made of an insulator filled with an arc-extinguishing gas and attached to the main circuit container (1). A fixed terminal (2), a fixed arc contact (3) attached to the fixed terminal (2), a drive coil (8) surrounding the fixed arc contact (3) and attached to the fixed terminal (2), The fixed main contact (9) attached to the fixed terminal (2) and the fixed arc contact (3) and the fixed main contact (9) are detachably supported around the drive coil (8). A movable arc contact (12C) provided at the tip of the movable electrode (12), and the movable electrode (12) has a base portion of the movable electrode (12).
(12a) and the intermediate conductor (1C) between the movable arc contact (12C).
In the rotary arc gas circuit breaker of the configuration provided with 2d),
The specific electric resistance of the intermediate conductor (12d) is set to a value between the specific electric resistance of the graphite and the specific electric resistance of the base (12a) of the movable electrode (12). The movable arc contact (12C) is provided with a fitting portion (12h) fitted in an uneven shape. Further, the material of the intermediate conductor (12d) is preferably a copper-tungsten alloy.
Further, the intermediate conductor (12d) and the movable arc contact (12C)
At the boundary (12g) or mating part (12h) with the intermediate conductor (1
It is preferable that at least one boundary layer having a specific electric resistance intermediate between 2d) and the movable arc contact (12C) is provided. The boundary layer has a tungsten content of 9%.
It may be a boundary layer of an alloy comprising 0 to 99% Wt, a boundary layer of graphite-copper impregnation, or a combination thereof. Further, the fitting portion (12h) may be screwed or shrink-fit. Therefore, no protrusion is formed on the movable arc contact during operation, and the movable arc contact made of graphite does not break due to mechanical impact force, so that the dielectric strength between the fixed arc contact and the movable electrode is kept high. . Further, since no arc is emitted at the main contact portion, the contact resistance is stabilized, and the interruption cannot be prevented. As a result, a rotary arc type gas circuit breaker having excellent breaking performance can be obtained.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side sectional view showing an open state of a rotary arc type gas circuit breaker of the present invention, and FIG. 2 is an enlarged side sectional view showing details of a movable arc contact in FIG. In the figure, the movable electrode 12 is configured as follows. That is, 12a is the base of the movable electrode 12, 12b is the movable main contact, 12c
Is a movable arc contact made of single-component graphite, 12
d is an intermediate conductor made of a copper-tungsten alloy, 12e is the outer periphery of the movable electrode 12, 12f is an arc, 12g is a boundary portion, and 12h is a fitting portion. The movable arc contact 12c is located on the outer periphery 12 of the movable electrode 12.
It has an outer peripheral shape formed by an arc 12f having a tangent to e, and the fixed arc contact 3 is pressed inward by a spring 5. An enlarged view of the boundary 12g is shown in the schematic diagram of FIG. As can be seen from FIG. 3, the intermediate conductor 12 at the boundary 12g
On the d side, a tungsten-rich boundary layer 12j having a tungsten composition of 90 to 99%, and on the movable arc contact 12c made of graphite, a graphite-copper impregnated boundary layer 12 impregnated with copper is formed.
i. This gradually changes the electric resistance from the movable arc contact 12c to the intermediate conductor 12d. In the fitting portion 12h, the movable arc contact 12c is provided with a screw portion on the intermediate conductor 12d, and is mounted by screwing. Then, the outer periphery 12e of the movable electrode 12 and the boundary 12g are connected by an arc 12f,
The structure is such that stress is not concentrated on the movable arc contact 12c made of graphite. Next, the operation of the rotary arc gas circuit breaker of the present invention will be described. When the movable electrode 12 in the closed state is urged downward by a mechanism (not shown), the movable electrode 12 is separated from the fixed main contact 9. At this time, the fixed arc contact 3 is in contact with the copper-tungsten alloy of the intermediate conductor 12d, and the contact resistance between the fixed arc contact 3 and the movable electrode 12 is kept low. The current was transferred to the fixed arc contact 3 without firing,
All current flows through the fixed arc contact 3. At this time, an attractive force acts between the fixed arc contacts 3 so that the intermediate conductor 12d
However, since the fixed arc contact 3 has not yet contacted the movable arc contact 12c, no mechanical impact is applied to the movable arc contact 12c which is graphite, and the graphite is not broken. Absent. When the movable electrode 12 further moves downward, the fixed arc contact 3 that has been in contact with the intermediate conductor 12d comes into contact with the movable arc contact 12c. At this time, since the outer peripheral shape of the movable arc contact 12c is formed from an arc 12f tangent to the outer periphery 12e of the movable electrode 12, and the fixed arc contact 3 is pressed inward by the spring 5, As moves downward, the fixed arc contact 3 moves inward on the outer periphery of the movable arc contact 12c while maintaining contact with the movable arc contact 12c. When the movable electrode 12 further moves downward, the fixed arc contact 3 stops moving inward at a predetermined position, and the fixed arc contact 3 and the movable arc contact 12c are separated to generate an arc. As the movable electrode 12 moved downward, the arc moved from between the fixed arc contact 3 and the movable arc contact 12c, between the arc runner 7 and the movable arc contact 12c, and was electrically connected between the arc runner 7 and the fixed terminal 2. A magnetic field is generated by the interruption current flowing through the drive coil 8, and the arc is rotated and driven to cool and extinguish at the current zero point. During the period from this arc to arc extinguishing, the foot of the arc on the movable electrode 12 side is always on the movable arc contact 12c made of graphite. Here, since graphite is a single component, when heated by the feet of the arc, it sublimates and is smoothly consumed, and does not form projections on the surface. In addition, movable arc contact 12c
Since the electrical resistance from the wire to the intermediate conductor 12d is gradually changed, there is no sudden change in electrical resistance at the boundary 12g,
No transient arc is generated at the boundary 12g, and the arc space is not contaminated with metal vapor. In the present embodiment, the fitting portion 12h between the movable arc contact 12c and the intermediate conductor 12d is screw-coupled. However, the present invention is not limited to this.

[0006]

As described above, the present invention has the following effects. (1) Since no projection is formed on the movable arc contact, no electric field concentration occurs. Therefore, it is possible to provide a circuit breaker in which the dielectric strength between the contacts is kept high and the breaking performance is excellent. (2) A mechanical impact force due to an attractive force acting between the fixed arc contacts is not applied to the movable arc contacts made of graphite. Therefore, it is possible to provide a circuit breaker having high reliability and excellent breaking performance without breaking graphite. (3) When the fixed main contact and the movable main contact are separated from each other, no spark is generated, and no arc is generated at the movable main contact. Therefore, it is possible to provide a circuit breaker that generates little electric heat and has no danger of destruction of the container due to electric arc. (4) A transient arc does not occur at the boundary between the movable arc contact and the intermediate conductor, and the arc space is not contaminated with metal vapor. Therefore, it is possible to obtain a circuit breaker in which the dielectric strength between the contacts is kept high and the breaking performance is excellent.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an open state of a rotary arc type gas circuit breaker of the present invention.

FIG. 2 is an enlarged side sectional view showing details of a movable arc contact of the present invention.

FIG. 3 is a schematic diagram showing details of a boundary portion of a movable arc contact according to the present invention.

FIG. 4 is a side sectional view showing an open state of a conventional rotary arc gas circuit breaker.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Main circuit container 12 Movable electrode 2 Fixed terminal 12a Base 3 Fixed arc contact 12b Movable main contact 4, 5, 10, 11 Spring 12c Movable arc contact 6 Arc extinguishing tube 12d Intermediate conductor 7 Arcrunner 12e Outer circumference 8 Drive coil 12f Arc 9 Fixed Main contact 12g Boundary part 12h Fitting part

Claims (7)

[Claims] 1. A main circuit container (1) made of an insulator filled with an arc-extinguishing gas, a fixed terminal (2) mounted on the main circuit container (1), and mounted on the fixed terminal (2). The fixed arc contact (3), the drive coil (8) surrounding the fixed arc contact (3) and attached to the fixed terminal (2), and the fixed terminal (2) surrounding the drive coil (8). The fixed arc contact (3) and the fixed main contact (9), and a movable electrode (12) supporting the fixed main contact (9) so as to be able to come and go. The movable arc contact (12C) provided at the tip is made of graphite, and the base of the movable electrode (12) is
(12a) and the intermediate conductor (1C) between the movable arc contact (12C).
2d), wherein the specific electric resistance of the intermediate conductor (12d) is set to the specific electric resistance of the graphite and the specific electric resistance of the base (12a) of the movable electrode (12). A rotating arc type gas shut-off, characterized in that a fitting portion (12h) is provided in which the intermediate conductor (12d) and the movable arc contact (12C) are fitted in an uneven shape. vessel. 2. A rotary arc gas circuit breaker according to claim 1, wherein said intermediate conductor is made of a copper-tungsten alloy. 3. The intermediate conductor (12d) and the movable arc contact
At least one boundary layer having an intermediate specific resistance between the intermediate conductor (12d) and the movable arc contact (12c) is provided at the boundary (12g) or the fitting portion (12h) with the boundary (12c). The rotary arc type gas circuit breaker according to claim 1 or 2, wherein: 4. At least one of the boundary layer (12g) and the fitting portion (12h) has a tungsten content of 90 to 99% Wt.
4. A rotary arc gas circuit breaker according to claim 3, wherein said boundary layer is made of an alloy of the following. 5. The rotary arc type of claim 3, wherein at least one of the boundary layer (12g) and the fitting portion (12h) is a graphite-copper impregnated boundary layer (12i). Gas circuit breaker. 6. A rotary arc gas circuit breaker according to claim 1, wherein said fitting portion (12h) is screw-connected. 7. The rotary arc gas circuit breaker according to claim 1, wherein said fitting portion (12h) is shrink-fitted.