JPH0465484B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a slit-type current limiting device that limits short-circuit current in a circuit breaker or the like by inserting a resistor into the circuit when breaking the circuit.

[Conventional technology]

Conventionally, the most common method for limiting and interrupting short-circuit current is to use a power fuse. This power fuse is widely used for both low and high voltages, but cannot be used repeatedly.

No-fuse breakers (NFBs) exist as devices that can be used repeatedly, but their use is limited to low-pressure areas.

As a method that can be used repeatedly in high pressure areas,
There is a method of commutation to a current limiting element, as shown in FIG. 4, which is used for DC cutoff and the like.

The principle is that in the energized state, the commutation switch 101
When an overcurrent occurs while the disconnect switch 102 is closed, the commutation switch 101 first becomes open, and the current limiting element 10 is connected in parallel with the commutation switch 101.
3 is connected, the current flows to the current limiting element, the current is limited by the resistance of this current limiting element (or the reactor), and the current, which has become a small value due to this current limiting action, is used for disconnection. The purpose is to break the circuit using the switch 102 and open the circuit.

In this method, the smaller the fuse wire diameter in the power fuse, the better the current limiting characteristics. There is also a usage that solves the problem by distinguishing between the current-limiting section and the current-limiting section.

In this method, the following two methods have been conventionally used for the commutation section to the current limiting element 103.

(a) The commutation part is a fuse and the current limiting element is also a fuse.

A current-carrying fuse is set in the commutation switch 101 shown in Fig. 4, and a current-limiting fuse or current-limiting resistor is set in the current-limiting element 103, and the current-carrying fuse forcibly blows out the current-carrying element by explosion. (For example, JP-A-55-95241).

(b) The commutation part is a switching contact and the current limiting element is a current limiting resistor or fuse.

This uses a switching contact such as a circuit breaker in the commutation section (for example, Japanese Patent Laid-Open No. 55-21872).

[Problem that the invention seeks to solve]

However, in these conventional systems, the three functions of the commutation section, the current limiting element, and the disconnection section are each configured independently, resulting in a large number of parts and an increase in size.

The present invention solves the problems of conventional devices, enables repeated use at high voltages, shares the switching contacts of the commutation section and the disconnection section, and reduces the number of parts, downsizes, and simplifies switching operations. The object of the present invention is to obtain a narrow gap commutation type current limiting device.

[Means for solving problems]

The current-limiting device of the present invention is a current-limiting device in which a pair of contacts are disposed, and an arc generated when these contacts are opened is transferred over a resistive arc runner electrode to limit a breaking current. Connect both ends of a pair of resistive arc shorting arc runner electrodes to a fixed electrode and a movable electrode arranged oppositely,
A pair of arc extinguishing plates are disposed on both sides of the arc path of the resistive arc runner electrode in such a manner that the width gradually becomes narrower toward the discharge port at the end, and in the middle of the arc runner electrode, A U-shaped intermediate electrode is provided that protrudes toward the narrow end, and a commutation section is formed by short-circuiting one of the arc runner electrodes and the intermediate electrode using a short-circuiting rod, and a portion that is not short-circuited by the short-circuiting rod is used as a disconnection section. It is composed of

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

Fig. 1 is a longitudinal sectional view showing the configuration of an embodiment of the present invention, Fig. 2 is a front sectional view taken from the - line in Fig. 1, and Fig. 3 is a perspective view with one of the arc-extinguishing plates removed. It is a diagram.

In the figure, arc runner electrodes (hereinafter referred to as "runner electrodes") 3 and 4 are provided in parallel above each of a fixed electrode 1 and a movable electrode 2, and a U-shaped intermediate runner is provided between these runner electrodes 3 and 4. 3U of electrodes are provided. This intermediate runner electrode 3U and either one of the runner electrodes (first
In the figure and FIG. 2, a shorting rod 3B is connected between the runner electrode 3).

A commutation section is formed between the runner electrode 3 short-circuited by the short-circuiting rod 3B and the intermediate runner electrode 3U, and the short-circuiting rod 3
A disconnection section is defined between the runner electrode 4 and the intermediate runner electrode 3U that are not short-circuited at B.

In the above configuration, the materials of the runner electrodes 3, 4, the intermediate runner electrode 3U, and the shorting rod 3B are resistive, such as carbon having a specific resistance value ρ of 1000 μΩ-cm or more.

The arc-extinguishing plate 6 has protrusions 3a and 4a of the runner electrodes.
The arc-extinguishing plate has runner electrodes 3 and 4, a shorting rod 3B, and an intermediate runner electrode 3, as shown in FIG.
It has a groove that is slightly wider than those, so that the U can be accommodated.

The space formed by sandwiching both arc-extinguishing plates 6 is called a narrow gap, and this narrow gap is wide near the electrodes, and the runner electrodes 3 and 4 and the intermediate runner are at the tip of the electrode 3U. It is narrowly formed.
The opening of this narrow slit serves as the discharge port 9.

With the above configuration, by covering the fixed electrode 1, movable electrode 2, runner electrodes 3, 4, intermediate runner electrode 3U, and arc extinguishing plate 6 with the insulating container 7, the fixed electrode 1 and the movable electrode The space between the two and the narrow space is formed as a pressurization chamber 10.

The fluid passage from this pressurization chamber 10 is discharged into the atmosphere 11 through a discharge port 9.

The movable electrode 2 and the runner electrode 4 on the movable side are electrically connected to the current collector 5 and the conductive current collector housing 5.
A and also serves as a seal between the pressurizing chamber 10 and the atmosphere 11.

Next, the operation will be explained.

In a normal energized state, the fixed electrode 1 and the movable electrode 2 are in contact, as shown by the broken line in FIG. Moreover, the open state is shown by a solid line.

When an overcurrent occurs, the movable electrode 2 is opened by an external mechanism (not shown), and an arc is generated between the fixed electrode 1 and the movable electrode 2.

This arc is elongated with the opening operation of the movable electrode 2, becomes arcuate, and finally moves to the runner electrodes 3 and 4. The current path at this time is: external terminal → fixed electrode 1 → fixed side runner electrode 3 ← runner electrode protrusion 3a → arc 8a → runner electrode protrusion 4a → movable side runner electrode 4 → current collector housing 5A → external terminal . This path has a convex shape, and the magnetic field generated by the current flowing through the runner electrodes 3 and 4 acts perpendicularly to the arc current,
Due to Fleming's left hand rule, the arc 8a tends to move upward in FIG.

This electromagnetic force causes the arc 8a to move through the gap space toward a narrower gap. During the period from the generation of the arc until the arc 8a runs through the slit space, the gas in the pressurizing chamber 10 is heated by the arc heat (5,000 to 10,000 degrees Celsius), and the pressure increases.

Similarly, when the arc 8a and the arc extinguishing plate 6 come into contact with each other, a part of the wall of the arc extinguishing plate 6 forming the arc extinguishing chamber is melted and vaporized. These vaporized and thermally dissociated molecules contribute to the pressure increase.

The pressure increase during this period is made possible by forming a pressurization chamber 10 that is sealed from the atmosphere 11, and since a pressurization chamber is not formed in a conventional air switch, no pressure increase can be expected.

This pressure increase, together with the electromagnetic force due to the magnetic field generated from the current path, also serves as a force that moves the arc 8a to the narrower gap in the upper part of FIG.

Next, the arc 8a moving upward in FIG. 1 contacts the intermediate runner electrode 3U and is divided into arcs 8b and 8c. Note that the intermediate runner electrode 3
In this embodiment, there is one commutation section formed by U and the shorting rod 3B, but a plurality of commutation sections may be provided.

Next, as the divided arcs 8b and 8c move toward the narrower side of the slit, the arcs move to a gap length where the diameter of the arc is larger than the slit gap length. An occlusion occurs that closes the Due to the blockage caused by this arc, the pressurizing chamber 10 is completely sealed, and the pressure in the pressurizing chamber 10 further increases. This pressure increase causes each segmented arc to enter a narrower slit.

In addition, a resistive runner electrode 4,
5 and a part of the intermediate runner electrode 3U have been inserted into the circuit, the breaking current is limited as the arc moves, the diameter of the arc decreases, and the arc becomes easier to insert into narrower gaps. . The above current path is shown by the arrow in FIG.

At this time, the arc 8b of the commutation section is short-circuited by the remaining runner electrodes 3 shown by broken lines in FIG. 3 other than the current path, the intermediate runner electrode 3U, and the shorting rod 3B. arc 8b
Let r _a be the arc resistance of , and r _p be the resistance of the resistive electrode shorting the arc 8b, then r _a > r _p
The arc 8b disappears under the commutation condition.

In the present invention, arc resistance r _a
As the resistance r p increases, the resistance r _p indicated by the broken line in FIG. 3 decreases, making it easier to realize the commutation condition r _a >r _p .

Another factor that enables this commutation condition to be achieved quickly is that the arc's slit insertion effect is promoted by the pressure increase in the pressure boosting chamber 10.

Next, when the arc 8b is extinguished, the breaking current is transferred to the runner electrode 3, the shorting rod 3B and the intermediate runner electrode 3.
Commutation occurs in a part of U, a resistor is inserted into the circuit, and the disconnection arc 8c is inserted into a narrower gap due to the gap insertion effect due to the pressure increase in the boosting chamber 10, and is interrupted at the zero point of the breaking current. Then, the arc 8c disappears. The extinction of the arc 8c serves as a disconnection section as long as the movable electrode 2 is in the open state.

〔Effect of the invention〕

As described above, the present invention provides the following effects.

With only a pair of switching electrodes, a commutation section and a disconnection section are created by high-speed transition of the arc and its separation.Furthermore, since the commutation section is made of a resistive arc runner electrode and an intermediate runner electrode, commutation is facilitated as the arc transitions. , the runner electrode can be made thinner to increase the resistance value of the runner electrode.

Since the pressurizing chamber is shaped so that the arc moves into a narrower slit, the number of parts and size can be reduced, and the current limiting effect of the current limiting device can be significantly enhanced.

Unlike conventional fuses, it can be used repeatedly.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view showing an embodiment of the present invention, Fig. 2
The drawings are a side sectional view taken along the - line in FIG. 1, FIG. 3 is a sectional perspective view of this embodiment, and FIG. 4 is a circuit diagram showing the configuration of a conventional device. 1: fixed electrode, 2: movable electrode, 3: runner electrode, 3a: protrusion, 3U: intermediate runner electrode,
4: Runner electrode, 5: Current collector, 5A: Current collector housing, 6: Arc-extinguishing plate, 7: Insulating container, 8a~
8c: arc, 9: discharge port, 10: pressurization chamber, 1
1: Atmosphere.

Claims (1)

[Claims] 1. A current limiting device in which a pair of contacts are disposed, and an arc generated when these contacts are opened is transferred over a resistive arc runner electrode to limit a breaking current, comprising: Fixed electrode 1 and movable electrode 2 arranged as
Both ends of a pair of resistive arc short-circuiting arc runner electrodes 3 and 4 are connected, and a narrow wire is formed on both sides of the arc path of the resistive arc runner electrodes 3 and 4 as it goes toward the discharge port 9 at the end. A pair of arc extinguishing plates 6 are disposed in a state that gradually narrows, and a U-shaped intermediate electrode 3U is provided midway between the arc runner electrodes 3 and 4 to protrude toward the narrow direction, and one of the arc runners A current limiting device characterized in that an electrode 3 and an intermediate electrode 3U are short-circuited by a short-circuiting rod 3B to form a commutation section, and a portion not short-circuited by the short-circuiting rod 3B is configured as a disconnection section. 2 The narrow part formed by the arc extinguishing plate 6 located farthest from the contacts of the electrodes 1 and 2 is left as the discharge port 9, and the other constituent members, such as the contacts, the arc extinguishing plate 6, and the arc runner Electrodes 3 and 4 are placed in an insulating container 7
2. A current limiting device according to claim 1, which is hermetically sealed.