JP2000133094A - Gas-blast circuit breaker having closing resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-blast circuit breaker maintaining superior breakdown strength performance and having improved reliability by preventing fusion of fixed and moving contacts of a closing resistance contact part caused by a pre-arc occurring between the contacts. SOLUTION: A front end center of a fixed contact 33 is provided with an arc-resistant part 33a made of a tungsten alloy such as a copper-tungsten alloy or pure tungsten, while a front end of a moving contact 34 is provided an arc- resistant part 34a facing to the arc-resistant part 33a by screwing or silver- soldering. The arc-resistant part 34a is made of a tungsten alloy such as a copper-tungsten alloy or pure tungsten as well as the arc-resistant part 33a. The arc-resistant parts 33a, 34a have hemispherical shapes, while the curvature of the arc-resistant part 34a is set to smaller than that of the arc-resistant part 33a.

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 with a closing resistor for suppressing a closing overvoltage at closing, and more particularly to a fixed contact of a closing resistor contact portion electrically connected in series to the closing resistor. This is an improvement in the configuration of the contact and the movable contact.

[0002]

2. Description of the Related Art In recent years, power demand has been increasing, and the capacity of power transmission systems has been increasing. Therefore, large-capacity gas circuit breakers such as 550 kV class are used in substations and switchyards. In order to ensure excellent reliability in such a gas circuit breaker, it is desirable to suppress a supply overvoltage at the time of supply. Therefore, a gas circuit breaker with a closing resistance has been conventionally proposed. What is a gas circuit breaker with closing resistance?
This is a device in which a closing resistance contact having a closing resistance is provided in parallel with the main contact of the circuit breaker, and the main contact can be closed in a state where the closing overvoltage is suppressed by the closing resistance.

Here, a puffer type gas circuit breaker with a closing resistor will be described in detail with reference to FIGS. 8 and 9. FIG. As shown in FIG. 8, the gas circuit breaker 1 is provided with a sealed container 2 in which an insulating gas is sealed. In this container 2, a shut-off portion 3 is housed. The interrupting section 3 includes an arc-extinguishing chamber 4 as a main contact and a closing resistance contact section 5. Here, a single-point gas circuit breaker will be described, but the basic configuration and concept of the two-point and four-point gas circuit breakers are the same.

In the arc-extinguishing chamber 4, a fixed part 6 and a movable part 7 are arranged to face each other. Among them, the movable portion 7 includes a movable contact 12 for supplying a normal current, a movable arc contact 13,
An insulating nozzle 14, an operation rod 15, and a puffer cylinder 16 formed of a conductive material are integrally assembled. A puffer piston 20 is slidably inserted into the puffer cylinder 16, and each member constituting the movable portion 7 operates along the puffer piston 20 together with the puffer cylinder 16. The puffer piston 20 forms a compression chamber together with the puffer cylinder 16. Further, as members for supporting the movable portion 7, a supporting insulating cylinder 17, a shield 18 of the supporting insulating cylinder 17, a movable support 19 and a puffer piston 20 are provided.
Is provided. Further, a lever 29 and an insulation operation rod 30 are attached to the operation rod 15, and an operation mechanism (not shown) in a mechanism box 31 is connected to the insulation operation rod 30.

On the other hand, the fixed part 6 is composed of a fixed energizing finger 8 for applying a normal current, a fixed arc contact 9, a fixed side shield 10, and a fixed support 11 made of a conductive material for supporting these. An insulating rod 21 is attached to the fixed support 11, and the fixed portion 6 is supported by the movable support 19 via the insulating rod 21. The insulating rod 21 may be replaced with an insulating cylinder or a capacitor.

Further, a conductor 32 is attached to the fixed support 11. A closing resistor 28 for suppressing an overvoltage at the time of closing is mechanically fixed to the fixing portion 6 and electrically connected in parallel via the conductor 32.

Next, the closing resistance contact section 5 will be described. The closing resistance contact section 5 is provided with a closing resistance fixing section 22 and a movable contact 23 facing each other. Among them, the closing contact fixing portion 22 is connected to the fixing support 1 via an insulating member 24.
Fixed to 1. The closing resistor 28 is mechanically fixed to the closing contact fixing section 22 and is electrically connected in series. Further, a spring 26 is built in the closing contact fixing portion 22, and a fixed contact 25 is attached to a tip end of the spring 26. 8, the fixed contact 25 is moved by the spring 26 to the movable contact 23.
It is held in the side position.

On the other hand, the movable contact 23 is mechanically fixed to the lever 29 and is electrically connected thereto. Therefore, at the time of closing and opening, the driving force of the operating mechanism in the mechanism box 31 is transmitted to the movable section 7 of the arc-extinguishing chamber 4 and the movable contact 23 of the closing resistance contact section 5, and both are driven collectively. It is supposed to be.

In the closing resistance type gas circuit breaker 1 having the above-described configuration, at the time of closing, the movable contact 23 first contacts the fixed contact 25 to close the closing resistance contact portion 5, and in this state, the main contact Can be inserted. Therefore, the closing resistor 27 connected to the closing resistor contact portion 5 can reliably suppress the closing overvoltage at closing, and the gas circuit breaker 1 can exhibit high reliability in a large capacity system.

[0010]

During the closing operation of the closing resistance contact section 5, the movable contact 23 is fixed to the fixed contact 25.
, A potential difference exists between the movable contact 23 and the fixed contact 25. Therefore, both contacts 23,
Before the physical contact of 25, dielectric breakdown occurs and electrical connection occurs. That is, as shown in FIG.
An arc current called a pre-arc 27 is generated between 25. When a no-load transmission line is inserted in the gas circuit breaker 1, since an injection command is issued at a random phase, the relative position between the movable contact 23 and the fixed contact 25 when the pre-arc 27 occurs is also random, The generation of the pre-arc 27 is inevitable.

The arc root of the pre-arc 27 is as follows:
It exists on the surface of the contacts 23 and 25. Therefore, the surface temperature of the contacts 23 and 25 rises extremely due to the concentration of the arc current. Usually, the movable contact 23 and the fixed contact 25
Is made of iron or copper, the constituent materials of the contacts 23 and 25 may be melted by the temperature rise.

When the closing resistance contact portion 5 performs the closing operation in a state where the constituent materials of the contacts 23 and 25 are melted, the following problem occurs. That is, the impact of the movable contact 23 colliding with the fixed contact 25 causes the molten contact 23,
After the constituent material 25 scatters as particles, or is deformed by being sandwiched between the contacts 23 and 25, the contact 2
Or drop off from 3,25. The constituent materials of the contacts 23 and 25 that have fallen into the container 2 in this way accumulate as metal foreign matter in the container 2, resulting in a decrease in withstand voltage performance between the power application portion and the container 2.

When the closing resistance contact section 5 repeats the closing operation many times, the movable contact 23 and the fixed contact 2
At the tip of No. 5, plastic deformation occurs. Usually, the contacts 23, 2
Since 5 is made of the same material, its hardness is equal, and the degree of deformation of both is uncertain. Therefore, contact 2
It is difficult to estimate the amount of deformation at the tips of the contacts 3 and 25, and the potential distribution between the contacts 23 and 25 fluctuates, causing a large variation in the firing voltage. As a result, generation of the pre-arc 27 becomes unstable, and the frequency of melting the contacts 23 and 25 may increase.

The present invention has been proposed in order to solve the above problems, and a main object of the present invention is to prevent a contact arc from being melted by a pre-arc generated between contacts of a closing resistance contact portion. Suppresses the generation of metallic foreign substances,
An object of the present invention is to provide a gas circuit breaker with a closing resistance that maintains excellent withstand voltage performance and contributes to improvement in reliability. It is another object of the present invention to provide a gas circuit breaker with a closing resistor that stabilizes a generated prearc, reliably prevents melting of a contact, and increases reliability.

[0015]

In order to achieve the above object, according to the first aspect of the present invention, an arc extinguishing chamber is housed in a container filled with an insulating gas. The closing resistance for suppressing the power supply is electrically connected in parallel, and the closing resistance contact portion is electrically connected in series to this closing resistance,
In a gas circuit breaker with a closing resistance in which a fixed contact and a movable contact are arranged opposite to a closing resistance contact portion, an arc-resistant portion made of tungsten or a tungsten alloy is provided at a tip of the movable contact and the fixed contact. It is characterized by being provided.

In the first aspect of the present invention having the above structure, the melting point of the arc-resistant portion made of tungsten or a tungsten alloy is sufficiently higher than the temperature of the arc root of the pre-arc. Therefore, even if a pre-arc is generated in the arc-resistant portions of the movable contact and the fixed contact during the closing operation of the closing resistance contact portion, the arc-resistant portion does not melt. Therefore, even if the movable contact and the fixed contact collide at the time of injection,
The constituent material of the contact does not fall into the container, the generation of metal foreign matter is suppressed, and excellent withstand voltage performance can be maintained.

According to a second aspect of the present invention, in the gas circuit breaker with a closing resistance according to the first aspect, an arc-resistant portion is provided in a portion having an electric field of 50% or more of the maximum electric field in the movable contact and the fixed contact. It is characterized by having. According to the second aspect of the present invention, since the portion having an electric field of 50% or more of the maximum electric field at the tips of the movable contact and the fixed contact is covered by the arc-resistant portion, even if the discharge is slightly varied, Pre-arc can be reliably fired on the arc-resistant part.

According to a third aspect of the present invention, in the gas circuit breaker with a closing resistance according to the first or second aspect, the curvature of the tip of the fixed contact is different from the curvature of the tip of the movable contact. I do. Generally, when a voltage is applied between two contacts, the electric field is higher at the tip of the contact having the smaller curvature. According to the third aspect of the present invention, since the curvatures of the two contact tips are different from each other, the discharge start during the closing operation can be dominant at the contact tip having the smaller curvature. Therefore, it is possible to easily estimate the discharge starting voltage, grasp the potential distribution between the contacts, and generate a pre-arc on the arc-resistant part in a stable state. Thereby, melting of the constituent material of the contact can be prevented.

The invention according to claim 4 is the invention according to claim 1, 2 or 3.
In the gas circuit breaker with closing resistance described, the arc-resistant part is provided on the contact surface of the fixed contact and the movable contact, and the component ratio of tungsten in the arc-resistant part on the fixed contact side,
It is characterized in that the component ratio of tungsten in the arc resistant part on the movable contact side is different from that of tungsten. According to the above-described invention, since the component ratio of tungsten is different between the arc-resistant part on the fixed contact side and the arc-resistant part on the movable contact side, the hardness of both is different, and the tungsten component ratio is different. The higher the contact, the higher the hardness. Generally, when the hardness of two metal objects is different, the softer one is deformed, and the harder one is not. Therefore, it is possible to easily estimate the deformation state of the arc-resistant portion located on the contact surface of the fixed contact and the movable contact after the closing operation is repeated many times. Based on this estimation, the shape design of the arc resistant part in the contact can be performed. Thus, it is possible to stably generate the pre-arc on the arc-resistant portion, and to prevent the constituent material of the contact from melting as in the third aspect of the present invention.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. The gas circuit breaker according to the following embodiment includes an arc extinguishing chamber 4 and a closing resistance contact portion 5 which are housed in a container 2 filled with an insulating gas. The basic configuration of the resistance contact portion 5 is the same as that of the conventional gas circuit breaker 1 shown in FIGS. Therefore, the same portions as those of the conventional example shown in FIGS. 8 and 9 are denoted by the same reference numerals, and description thereof will be omitted.

(1) First Embodiment [Configuration] A first embodiment corresponding to the first to third aspects of the present invention will be described with reference to FIGS. FIG. 1 is an enlarged sectional view of the vicinity of a closing contact portion according to the first embodiment,
FIG. 2 is a cross-sectional view showing the entire first embodiment.

First, as shown in FIG. 1, a fixed contact 33 and a movable contact 34 are arranged on the closing resistance contact portion 35 so as to face each other. Among them, an arc-resistant portion 33a made of a tungsten alloy such as copper tungsten or pure tungsten is provided at the center of the tip of the fixed contact 33. The connection part 33b is screwed into the arc resistant part 33a,
Silver is attached. The fixed contact 33 is screwed into the connection portion 33b, whereby the fixed contact 33 is electrically connected to the closing resistor 28 in series. The connecting portion 33b and the fixed contact 33 are made of a metal material such as iron or copper, similarly to the conventional fixed contact 25.

The tip of the movable contact 34 has an arc resistant part 3
An arc resistant part 34a is provided by screwing and silver brazing so as to be in contact with 3a. The arc-resistant part 34a is made of a tungsten alloy such as copper tungsten or pure tungsten similarly to the arc-resistant part 33a. The arc resistant part 34a is hemispherical, and its curvature is set smaller than the curvature of the arc resistant part 33a. The constituent materials of the movable contact 34 other than the arc-resistant portion 34a are the same as those of the conventional movable contact 23.

The semi-spherical arc-resistant portion 34a covers a portion of the movable contact 34 having an electric field of 50% or more of the maximum electric field. In this regard, FIG.
This will be described in detail with reference to FIG. FIG. 3 shows the calculation result of the electric field distribution on the surface of the movable contact 34, and shows the electric field intensity at that portion. When the angle from the central axis of the movable contact 34 is represented by θ, the maximum electric field is about 50% at θ = 45 degrees. The hemispherical arc resistant part 34a sufficiently covers this part.

If the radius of the hemispherical surface of the arc-resistant part 34a is R, the surface area from the angle 0 to θ is 2πR
² (1−cos θ), which is about 30% of the hemisphere when θ = 45 degrees. That is, the arc resistant part 34a
In order to cover the portion of the movable contact 34 having an electric field of 50% or more of the maximum electric field, the surface area of the arc-resistant part 34a only needs to be 30% or more of the surface area of the hemispherical surface.

[Operation and Effect] The operation and effect of the first embodiment having the above configuration are as follows. That is, during the closing operation of the closing resistance contact section 5, the arc-resistant sections 33a, 34 of the fixed contact 33 and the movable contact 34.
Although a pre-arc 27 is generated at a, the melting points of the arc resistant portions 33a and 34a made of tungsten or a tungsten alloy are higher than the temperature of the arc root of the pre-arc 27. Therefore, the arc-resistant parts 33a, 3
4a does not melt. Therefore, even if the arc resistant parts 33a and 34a collide with each other at the time of injection, the contacts 34 and
It is possible to prevent metal foreign matter from being generated without dropping from the inside of the container 2 into the container 33. Thereby, the withstand voltage performance between the power application part and the container 2 can be maintained, and excellent reliability can be secured.

In the first embodiment, since the curvature of the arc resistant part 34a is smaller than the curvature of the arc resistant part 33a, the electric field is increased. Therefore, pre-arc 2
The discharge start of 7 is dominant at the tip of the movable contact 34. Therefore, the discharge starting voltage can be easily estimated, and the contact 3
By grasping the potential distribution between the arcs 3 and 34, the pre-arc 27 can be generated on the arc-resistant parts 33a and 34a in a stable state. In addition, the hemispherical arc-resistant portion 34a covers a portion having an electric field of 50% or more of the maximum electric field at the tip of the movable contact 34. As a result, even if the discharge varies to some extent, the pre-arc 2
7 can be ignited and the constituent materials of the contacts 33 and 34 can be reliably prevented from melting.

(2) Second Embodiment [Configuration] Next, a second embodiment corresponding to the invention of claim 4 will be described. As shown in the pie chart of FIG. 4, in the second embodiment, the tungsten component ratio in the arc-resistant part 33 a on the fixed contact 33 side is higher than that in the arc-resistant part 34 a on the movable contact 34 side. It is characterized in that it is configured to be greater than the component ratio.

[Operation and Effect] In the second embodiment as described above, the tungsten component ratio is higher in the arc-resistant part 4a on the movable contact 34 side than in the arc-resistant part 33a on the fixed contact 33 side. Because there are many, hardness is high. Therefore, even if the closing resistance contact portion 5 repeats the closing operation many times, only the arc resistant portion 33a is deformed. As described above, it is easy to estimate the state in which only one of the arc-resistant portions 33a is deformed, and the shape of the contacts 33 and 34 can be designed based on this. As a result, the pre-arc 27 can be stably generated on the arc-resistant portions 33a, 34a, and the constituent materials of the contacts 33, 34 are prevented from melting, thereby maintaining the withstand voltage performance and improving the reliability. Can contribute.

(3) Other Embodiments The present invention is not limited to the above embodiments, but also includes the following other embodiments. That is, as another embodiment including the inventions of claims 3 and 4,
As shown in FIG. 5, by making the arc resistant part 33c on the fixed contact 33 side of the semispherical arc resistant part 34a flat, the curvatures of both may be different. Further, as in the second embodiment, the proportion of tungsten in the arc-resistant part 34a on the movable contact 34 side is made larger than the proportion of tungsten in the arc-resistant part 33c on the fixed contact 33 side.

According to such an embodiment, since the arc-resistant part 34a is harder than the arc-resistant part 33c, when the two collide, the arc-resistant part 33c is deformed so as to be depressed. Therefore, the curvature of the arc-resistant part 34a always remains smaller, the arc-resistant part 34a governs the start of discharge, and its electric field is almost the same as before the collision. That is, even after repeated collisions of the contacts 33 and 34, the potential distribution during the collisions hardly changes, the pre-arc 27 can be generated in a stable state, and a highly reliable gas circuit breaker is provided. Can be.

Further, the shape and size of each component or the assembling structure can be appropriately changed. For example, an assembling structure of the fixed contact 33 as shown in FIGS. 6 and 7 can be proposed. FIG. 6 shows an assembly process of the fixed contact 33, in which the arc-resistant part 33a is screwed into the connecting part 33b with a right-hand screw 35. In FIG. 7, after the arc resistant part 33a is screwed to the connecting part 33b, it is screwed into the fixed contact 33 with the left screw 36. When a left-handed screw is used in assembling in FIG. 6, a right-handed screw is used in assembling in FIG.

According to such an embodiment, the fastening state of the fixed contact 33 can be strengthened for the following reasons. As can be understood from FIGS.
7 is larger in diameter than the connecting portion 33b, and therefore, when assembling in FIG. 7, the connecting portion 33b is inserted into the fixed contact 33 from the right side in the drawing (the direction of the arrow 37). The connecting portion 33b and the fixed contact 33 are tightened, but must be tightened in the direction of the arrow 38 in order to avoid damaging the surface of the arc resistant portion 33a. At this time, since the screw 35 and the screw 36 are oppositely oriented screws, they are tightened to each other. Therefore, the fixed contact 33 can be assembled firmly.

[0034]

As described above, according to the present invention,
With a simple configuration in which an arc-resistant portion made of tungsten or a tungsten alloy is provided in a part of the fixed contact and the movable contact of the closing resistance contact portion, it is possible to prevent the contact from being melted by the pre-arc and to suppress the generation of metal foreign matter. Therefore, it is possible to provide a highly reliable gas circuit breaker with a closing resistance while maintaining excellent withstand voltage performance.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of the vicinity of a closing contact portion according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the entire first embodiment;

FIG. 3 is an electric field distribution diagram at the tip of a movable contact according to the first embodiment.

FIG. 4 is an arc-resistant part 33 according to a second embodiment of the present invention.
7A and 7B are pie charts showing the component ratios of tungsten at 34a.

FIG. 5 is an enlarged sectional view of the vicinity of a closing contact portion according to another embodiment of the present invention.

FIG. 6 is an assembly view of a fixed contact according to another embodiment of the present invention.

FIG. 7 is an assembly view of a fixed contact according to another embodiment of the present invention, following FIG. 6;

FIG. 8 is a cross-sectional view of the entire conventional gas circuit breaker with a closing resistance.

FIG. 9 is an enlarged sectional view showing the vicinity of a making contact in a conventional gas circuit breaker with a making resistance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 4 ... Arc extinguishing chamber 5 ... Making resistance contact part 6 ... Fixed part 7 ... Movable part 11 ... Fixed support 22 ... Making resistance contact fixing part 23, 34 ... Movable contact 24 ... Insulating member 25, 33 ... Fixed contact 26 ... Spring 27: Pre-arc 28: Closing resistance 33a, 33c, 34a: Arc-resistant part 35, 36: Screw

Claims (4)

[Claims] An arc-extinguishing chamber is accommodated in the container, and a closing resistance for suppressing an overvoltage at the time of closing is electrically connected to the arc-extinguishing chamber. A gas circuit breaker with a closing resistor, which is connected in parallel, a closing resistor contact portion is electrically connected to the closing resistor electrically in series, and a fixed contact and a movable contact are arranged opposite to the closing resistor contact portion. A gas circuit breaker with a closing resistance, wherein an arc-resistant part made of tungsten or a tungsten alloy is provided at a tip of the movable contact and the fixed contact. 2. The gas with a closing resistance according to claim 1, wherein the arc resistant portion is provided at a portion of the movable contact and the fixed contact having an electric field of 50% or more of a maximum electric field. Circuit breaker. 3. The gas circuit breaker with a closing resistance according to claim 1, wherein the curvature of the fixed contact tip is different from the curvature of the movable contact tip. 4. The arc resistant part is provided on a contact surface of the fixed contact and the movable contact, and a tungsten component ratio in the arc resistant part on the fixed contact side and an arc resistant on the movable contact side. 4. The gas circuit breaker with a closing resistance according to claim 1, wherein the component ratio of tungsten in the section is different.