JPH1186697A - Puffer type gas circuit breaker for DC - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve DC interrupting performance by extending an arc at the time of interrupting. A gas flow path (8) is formed at an axially intermediate portion of an insulating nozzle (7) to allow an insulating gas from a puffer chamber (6) to penetrate radially outward. Extend the length of.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC puffer type gas circuit breaker for interrupting power by using, for example, a neutral line of a DC power system, and more particularly to a structure of an arc extinguishing chamber.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view conceptually showing an arc-extinguishing chamber of a conventional puffer type gas circuit breaker similar to that disclosed in, for example, Japanese Patent Publication No. 7-19524. Show. In the figure, 1 is a cooling cylinder, 2 is a fixed contact fixed to the support portion 1a of the cooling cylinder 1, 3 is a fixed cylinder, 4 is a movable contact slidably fitted inside the fixed cylinder 3, and 5 is a movable contact. A movable cylinder integrally formed with the contact 4, 6 is a puffer chamber formed by the inner peripheral surface of the movable cylinder 5, the outer peripheral surface of the movable contact 4, and the flange 3 a of the fixed cylinder 3, and 7 is from the bottom of the movable cylinder 5 An insulating nozzle extending in the axial direction.

Next, the operation will be described. In the closed position, the fixed contact 2, the contact portion 4a, and the movable contact 4 constitute an electric path. Although not shown, the fixed contact 2 and the movable contact 4 are respectively connected to predetermined conductive parts, and the gas circuit breaker is closed. I do. When the opening operation is started, the movable contact 4, the movable cylinder 5, the insulating nozzle 7
Move together in the direction of the arrow and move the movable contact 4
The contact portion 4a of the contact 4a is separated from the end of the fixed contact 2 while slidingly contacting the fixed contact 2 and is located at the middle of the opening shown in FIG. At this time, if a current is flowing through the electric circuit, the arc 2 is located between the tip of the contact portion 3a and the fixed contact 2.
0 occurs.

On the other hand, the volume of the puffer chamber 6 is compressed by the opening operation, and the pressure of the insulating gas inside the puffer chamber 6 is increased. The pressure of the insulating gas is ejected from the ventilation hole 5a of the movable cylinder 5 and passes through the throat portion 7a of the insulating nozzle 7. The arc 20 is blown to the cooling of the arc 20. In the case of the AC circuit breaker, there is a timing at which the current becomes zero twice during one cycle, and therefore, the arc 2 caused by the blowing of the gas flow from the puffer chamber 6 described above.
In combination with the cooling effect of 0, the arc 20 is extinguished and the current is cut off at the timing of the current zero.

[0005]

When the above-mentioned extinguishing chamber is applied to a circuit breaker for a DC circuit, at least the following measures are required. That is, in the case of the DC circuit, there is no current zero point of the circuit current itself as in the case of the AC circuit, and it is necessary to forcibly create this current zero point. Therefore, a commutation circuit including a reactor and a capacitor is inserted in parallel with the fixed contact 2 and the movable contact 4. Then, an oscillating current is generated by the interaction between the resistance of the arc 20 (arc resistance) generated at the time of opening and the above-mentioned reactor and capacitor, and the amplitude of the oscillating current is made larger than the amplitude value of the DC current to thereby reduce the current zero point. It is forcibly created.

[0006] For example, an IEEE paper "Instabil"
entity of DC Arc inSF ₆ Circu
it Breaker "(PE-057-PWRD-0
-11-1996) introduces the characteristics of this DC arc. According to this, the speed at which the amplitude of the oscillating current expands depends on the arc characteristics (arc time constant and arc loss). This arc characteristic is an amount dependent on the arc resistance. As the arc resistance increases, the amplitude expanding speed of the oscillating current increases, and as the arc voltage decreases, the expanding speed decreases. Further, when the arc resistance falls below a certain level, the amplitude expansion speed becomes negative, that is, the amplitude decreases.

The point is that the arc resistance should be increased. However, if the arc-extinguishing chamber of the conventional puffer-type gas circuit breaker for AC circuits is used as it is, this increase in arc resistance is not sufficiently achieved, and sufficient breaking performance is obtained as a gas circuit breaker for DC circuits. Did not. The present invention has been made in order to solve the above-mentioned problems, and a DC puffer type that can greatly increase the arc resistance at the time of interruption without greatly changing the structure of a conventional puffer type gas circuit breaker. The purpose is to obtain a gas circuit breaker.

[0008]

According to a first aspect of the present invention, there is provided a direct current puffer type gas circuit breaker having a columnar fixed contact, a cylindrical shape disposed coaxially with the fixed contact and configured to be able to contact and separate from the fixed contact. A movable contact, a fixed cylinder slidably fitted on the outer periphery of the movable contact, and a slidably fitted outer periphery of the fixed cylinder, integrally formed with the movable contact, and a buffer formed by the fixed cylinder and the movable contact. A movable cylinder forming a chamber, and an insulation extending a predetermined length in the axial direction from the fixed contact side end of the movable cylinder, and guiding the compressed insulating gas in the puffer chamber to an arc generated in both of the contacts during a breaking operation. In a direct current puffer type gas circuit breaker provided with a substantially cylindrical insulating cylinder made of a material, the puffer chamber is provided at an axially intermediate portion of the insulating cylinder. It is obtained by forming a gas flow path through which the al insulating gas radially outward.

Further, in the DC puffer type gas circuit breaker according to the present invention, the gas flow path is defined in the circumferential direction of the insulating cylinder so as to be asymmetric with respect to the center axis of the insulating cylinder. Formed over an angle of.

According to a third aspect of the present invention, in the direct current puffer type gas circuit breaker according to the first or second aspect, the cross-sectional area of the gas flow path increases radially outward of the insulating cylinder. Things.

According to a fourth aspect of the present invention, there is provided a DC puffer type gas circuit breaker according to any one of the first to third aspects, wherein a gas cooling plate made of a metal material is provided on a surface of the insulating cylinder forming the gas flow path. It is provided.

According to a fifth aspect of the present invention, there is provided a DC puffer-type gas circuit breaker according to any one of the first to fourth aspects, wherein a plurality of gas passages are formed in the axial direction of the insulating cylinder. In the middle of the gas flow path, there is provided an insulating plate projecting a predetermined length radially outward from the outer periphery of the insulating cylinder.

According to a sixth aspect of the present invention, there is provided a DC puffer-type gas circuit breaker according to any one of the first to fifth aspects, wherein the gas guide hole for temporarily sucking the insulating gas from the puffer chamber and blowing the gas inward in the radial direction is provided. The insulating cylinder is formed at a circumferential position opposite to a circumferential position at which the gas flow path is formed, and the insulating gas passing through the gas guide hole is blown to the gas flow path.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a sectional view showing an arc-extinguishing chamber of a DC puffer-type gas circuit breaker according to Embodiment 1 of the present invention.
The figure shows the state at the time of closing. FIG. 2 is a diagram showing a cross section taken along line AA of FIG. In the drawing, reference numeral 1 denotes a cooling cylinder fixed in a tank constituting a gas circuit breaker by a mounting mechanism (not shown), 2 denotes a cylindrical fixed contact having one end fixed to a support portion 1a of the cooling cylinder 1, and 3 denotes a drawing. The left end is a cylindrical fixed cylinder fixed in the tank constituting the gas circuit breaker, and has a ring-shaped flange 3a at the right end. Reference numeral 4 denotes a cylindrical movable contact which is slidably fitted inside the fixed cylinder 3 and is moved in the axial direction by a drive mechanism (not shown) to make contact with and separate from the fixed contact 2. For this reason, the right end of the movable contact 4 has a contact portion 4a that makes elastic contact with the fixed contact 2.

Reference numeral 5 denotes a cylindrical movable cylinder which is concentrically arranged with the movable contact 4 and is formed integrally with the movable contact 4 at the bottom at the right end thereof. The cylinder 5 is slidably fitted on the outer periphery of the flange 3a of the fixed cylinder 3. It has a structure. And, between the bottom of the right end of the movable cylinder 5 and the movable contact 4,
A ventilation hole 5a for passing an insulating gas such as SF ₆ in the axial direction is formed. 6 is the inner peripheral surface and the bottom of the movable cylinder 5,
A puffer chamber formed by the outer peripheral surface of the movable contact 4 and the flange 3a of the fixed cylinder 3, and 7 is a movable cylinder 5
Extends axially to the right from the bottom of the right end to guide the compressed insulating gas in the puffer chamber 6 to arcs generated in the contacts 2 and 4 during the shut-off operation. For example, polytetrafluoroethylene (available from DuPont, USA) This is an insulating nozzle as an insulating cylinder made of a material (known by the trade name Teflon). Further, the insulating nozzle 7 is formed with gas flow paths 8 each having a hole penetrating radially in three places in the axial direction, as shown in FIG.

Next, the operation, particularly the operation at the time of opening, will be described. When the opening operation is started, the movable contact 4, the movable cylinder 5, and the insulating nozzle 7 move integrally in the direction of the arrow, and the contact portion 4a of the movable contact 4 comes into sliding contact with the fixed contact 2 and then comes into contact with the fixed contact. 2, an arc 20 is generated between the tip of the contact portion 3 a and the fixed contact 2.

On the other hand, the volume of the puffer chamber 6 is compressed by the opening operation, and the pressure of the insulating gas inside the puffer chamber 6 is increased. The arc 20 is blown to the cooling of the arc 20.

FIG. 3 is a diagram conceptually showing a state of the arc 20 and a gas flow (indicated by an arrow in the figure). Since the gas flow path 8 extending in the circumferential direction 180 ° is formed in the insulating nozzle 7, the flow of the insulating gas passing through the throat portion 7 a of the insulating nozzle 7 may proceed with a distribution symmetric with respect to the central axis. Instead, the gas is deflected toward the side where the gas flow path 8 is present (upward in FIG. 3), and is discharged from each gas flow path 8 radially outward.

With this gas flow distribution, arc 20 is
As shown in (2), the gas flow path 8 is stretched radially outward. That is, the arc length increases by this amount,
The arc resistance increases rapidly in combination with the increase in the cooling effect by the gas flow. As a result, an oscillating current is generated by the interaction of a not-shown commutation circuit composed of a reactor and a capacitor inserted between the fixed contact 2 and the movable contact 4, and furthermore, the above-described rapid change of the arc resistance occurs. Due to the increase, the amplitude of the oscillating current increases, and eventually becomes larger than the amplitude value of the DC current, thereby generating a current zero point. At this timing, the current is interrupted.

In the above description, the gas flow path 8 is formed over 180 ° in the circumferential direction of the insulating nozzle 7. However, the gas flow path 8 may be formed in consideration of the shapes and strokes of the contacts 2, 4 and the shape and strength of the insulating nozzle 7. The angle may be different.
Further, the formation angle may be changed for each gas flow path 8.
Further, the number of gas flow paths 8 is not limited to three. In addition, about the modification of these gas flow paths 8, the embodiment mentioned later is also considered similarly.

Embodiment 2 FIG. FIG. 4 is a sectional view showing an insulating nozzle 7 which is a main part of a DC puffer type gas circuit breaker according to Embodiment 2 of the present invention. That is, here, the gas flow path 8A is formed such that its cross-sectional area increases radially outward of the insulating nozzle 7.

As a result, the gas flow flowing out of the gas flow path 8A increases, and the arc 20 is easily bent. As compared with the case of the first embodiment, the arc resistance further increases, and the breaking performance is improved.

Embodiment 3 FIG. FIG. 5 shows a main part of a DC puffer type gas circuit breaker according to Embodiment 3 of the present invention. FIG. 4 is a cross-sectional view showing an insulating nozzle 7 That is, here, a gas cooling plate 9 made of a metal material (for example, tungsten copper or the like) is provided on the surface of the hole of the insulating nozzle 7 forming the gas flow path 8 shown in FIG.

Thus, when the arc 20 that has entered the gas flow path 8 comes into contact with the gas cooling plate 9, the temperature of the arc 20 decreases due to its heat capacity, and the amount of increase in arc resistance increases accordingly. As a result, the amplitude of the oscillating current increases due to the interaction with the commutation circuit, and the breaking performance is improved. The gas cooling plate 9 may be provided in the gas flow path 8A shown in FIG.

Embodiment 4 FIG. 6 is a sectional view showing an insulating nozzle 7 which is a main part of a DC puffer type gas circuit breaker according to Embodiment 4 of the present invention. That is, here, an insulating plate 10 that protrudes from the outer periphery of the insulating nozzle 7 radially outward by a predetermined length is provided in the middle of the gas flow path 8 adjacent in the axial direction.

This prevents the arc 20 that has entered the gas flow path 8 from contacting the outer periphery of the insulating nozzle 7 and causing a short circuit. Therefore, the high arc resistance value of the elongated arc 20 is maintained, and the improvement of the breaking performance due to the provision of the gas flow path 8 can be reliably exhibited. In FIG. 6, the insulating plate 10 is provided on the insulating nozzle 7 shown in FIG. 5, but the insulating plate 10 may be provided on the insulating nozzle 7 shown in FIG. 3 or FIG.

Embodiment 5 FIG. FIG. 7 is a sectional view showing an insulating nozzle 7, which is a main part of a DC puffer type gas circuit breaker according to Embodiment 5 of the present invention. That is, here, the gas guide hole 11 is formed at a circumferential position of the insulating nozzle 7 opposite to the circumferential position at which the gas flow path 8 is formed, in the example of FIG. The gas guide hole 11 is provided at the left end of the insulating nozzle 7 in the axial direction with the gas inlet 11a.
Are opened, and three gas outlets 11 b are opened on the inner periphery of the insulating nozzle 7.

A part of the insulating gas from the puffer chamber 6 once enters the gas guide hole 11 from the gas inlet 11a,
The gas is discharged from the gas outlet 11b in the radial direction and is blown to each of the gas flow paths 8 at the upper facing position. As a result, the gas flow passing through the gas flow path 8 increases as compared with the above-described embodiment, and the elongation amount of the arc 20 increases accordingly, so that the breaking performance is further improved.

In each of the above embodiments, the original shape of the insulating cylinder 7 is a nozzle shape symmetrical with respect to the central axis (insulating nozzle 7). However, it is not always necessary to be axially symmetric.
It may be an asymmetric, substantially cylindrical one.

[0030]

As described above, the DC puffer-type gas circuit breaker according to the first aspect of the present invention provides a gas flow path through which an insulating gas from a puffer chamber penetrates radially outward at an axially intermediate portion of an insulating cylinder. Is formed, the flow of the insulating gas entering the gas flow path extends the arc generated at the time of interruption, the arc resistance increases, the amplitude of the oscillating current increases, and the DC interruption performance improves.

Further, in the DC puffer type gas circuit breaker according to claim 2, the gas flow path is formed over a predetermined angle in the circumferential direction of the insulating cylinder so as to be asymmetric with respect to the center axis of the insulating cylinder. Therefore, the radial gas flow density increases, and the arc elongation effect increases.

Also, in the DC puffer-type gas circuit breaker according to claim 3, the cross-sectional area of the gas flow path increases radially outward of the insulating cylinder, so that the gas flow path passes through the gas flow path. As the gas flow rate increases, the arc tends to be deflected, and the arc elongation effect increases.

Further, in the DC puffer type gas circuit breaker according to claim 4, the surface of the insulating cylinder forming the gas flow path is provided on the surface of the insulating cylinder.
Since the gas cooling plate made of a metal material is provided, the arc contacts the gas cooling plate, the temperature of the arc decreases, and the arc resistance increases.

Further, in the DC puffer type gas circuit breaker according to claim 5, when a plurality of gas flow paths are formed in the axial direction of the insulating cylinder, the insulating gas flow path is provided between the gas flow paths adjacent in the axial direction. Since the insulating plate protruding radially outward from the outer periphery of the cylinder by a predetermined length is provided, there is an effect of maintaining a high arc resistance value of the arc extended by the gas flow path.

Further, in the DC puffer type gas circuit breaker according to claim 6, a gas guide hole for temporarily sucking the insulating gas from the puffer chamber and blowing it inward in the radial direction is formed in the insulating cylinder.
The gas flow path is formed at the circumferential position opposite to the circumferential position where the gas flow path is formed, and the insulating gas passing through the gas guide hole is blown to the gas flow path, so that the gas flow passing through the gas flow path is further increased. However, the arc elongation effect further increases.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an arc-extinguishing chamber of a DC puffer-type gas circuit breaker according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a cross section taken along line AA of FIG. 1;

FIG. 3 is a diagram conceptually showing a state of an arc 20 and a gas flow.

FIG. 4 is a sectional view showing an insulating nozzle 7 which is a main part of a DC puffer type gas circuit breaker according to Embodiment 2 of the present invention.

FIG. 5 is a cross-sectional view showing an insulating nozzle 7 which is a main part of a DC puffer type gas circuit breaker according to Embodiment 3 of the present invention.

FIG. 6 is a sectional view showing an insulating nozzle 7 which is a main part of a DC puffer type gas circuit breaker according to Embodiment 4 of the present invention.

FIG. 7 is a sectional view showing an insulating nozzle 7 which is a main part of a DC puffer type gas circuit breaker according to Embodiment 5 of the present invention.

FIG. 8 is a sectional view showing an arc extinguishing chamber of a conventional puffer type gas circuit breaker.

[Explanation of symbols]

2 fixed contact, 3 fixed cylinder, 4 movable contact, 5 movable cylinder, 6 puffer chamber, 7 insulating nozzle, 8, 8A gas flow path, 9 gas cooling plate, 10
Insulating plate, 11 gas guide holes, 20 arcs.

Claims (6)

[Claims] A fixed contact having a columnar shape, a cylindrical movable contact arranged coaxially with the fixed contact and configured to be able to contact and separate from the fixed contact, and a fixed member which is slidably fitted on the outer periphery of the movable contact. A cylinder, a movable cylinder slidably fitted to the outer periphery of the fixed cylinder, integrally formed with the movable contact, and forming a puffer chamber with the fixed cylinder and the movable contact; and a fixed cylinder side end of the movable cylinder. DC puffer type gas shut-off, which comprises a substantially cylindrical insulating cylinder made of an insulating material extending a predetermined length in the axial direction and guiding the compressed insulating gas in the puffer chamber to the arc generated in the contacts at the time of the shut-off operation. A gas flow passage through which the insulating gas from the puffer chamber passes radially outward at an axially intermediate portion of the insulating cylinder. DC for the puffer type gas circuit breaker according to claim. 2. The DC puffer gas according to claim 1, wherein the gas flow path is formed over a predetermined angle in a circumferential direction of the insulating cylinder so as to be asymmetric with respect to a center axis of the insulating cylinder. Circuit breaker. 3. The DC puffer type gas circuit breaker according to claim 1, wherein a cross-sectional area of the gas flow path increases radially outward of the insulating cylinder. 4. The puffer type gas circuit breaker for direct current according to claim 1, wherein a gas cooling plate made of a metal material is provided on a surface of the insulating cylinder forming the gas flow path. . 5. In the case where a plurality of gas flow paths are formed in the axial direction of the insulating cylinder, an insulating plate protruding a predetermined length radially outward from the outer periphery of the insulating cylinder in the middle of the gas flow paths adjacent in the axial direction. The puffer type gas circuit breaker for direct current according to any one of claims 1 to 4, further comprising: 6. A gas guide hole for temporarily sucking an insulating gas from a puffer chamber and blowing the gas inward in a radial direction is formed at a circumferential position of the insulating cylinder opposite to a circumferential position at which a gas flow path is formed. 6. The DC puffer type gas circuit breaker according to claim 1, wherein an insulating gas passing through a guide hole is blown to the gas flow path.