JPH0426168B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a slit-type current limiting device that limits short-circuit current by inserting a resistor into a circuit upon interruption.

[Conventional technology]

Conventionally, as a method for inserting a resistor into this type of circuit, the principle shown in Fig. 5 has been used (for example, Japanese Patent Laid-Open No. 49-14982, Japanese Patent Laid-Open No. 50-8063).
(as described in Japanese Unexamined Patent Application Publication No. 1983-121230).

That is, in FIG. 5, resistive arc runner electrodes (hereinafter referred to as runner electrodes) 400 and 5 are connected to the fixed electrode 100 and the movable electrode 200, respectively.
00, and the runner electrodes are arranged to face each other at an appropriate distance. Also 3
00 is a current collector that collects current from the movable electrode to the external terminal.

In this device, when the movable electrode 200 moves to the position indicated by the broken line in FIG.
0 and becomes energized. When the circuit is short-circuited and a short-circuit current is generated, the movable electrode 200 performs an "open" operation by an external mechanism (not shown) and moves to the position indicated by the solid line in FIG. 5. At this time, an arc is generated between the electrodes, and due to the convection effect due to the arc heat,
The arc moves to position a in Figure 5, then the magnetic field generated by the current acts on the arc, generating an upward electromagnetic force, and the arc rapidly moves upward from b to c to d in Figure 5. do.

At this time, since the runner electrodes 400 and 500 have resistance, the principle is that resistance is inserted into the circuit as the arc moves.

In this conventional method, the higher the resistance value of the runner electrode, the more effective it is when increasing capacity, improving current limiting performance, and downsizing. , ρ: specific resistance value, A:
area, l: length), it is necessary to take a method of increasing ρ or decreasing the area A of the runner electrode.

[Problem that the invention seeks to solve]

Here, if A is made smaller, the following problems will occur.

That is, in the conventional type, in the state of arc d in FIG. 5, the legs of the arc are on the runner electrodes 400 and 500,
They remain at a stalemate until the arc is cut off and disappears. Because of this sticking time, if the area A of the runner electrode is small, the tip of the runner electrode will be abnormally worn out, causing a problem in terms of durability. Furthermore, the stagnation of the arc after the arc d in FIG. 5 unnecessarily damaged the arc extinguishing plate (not shown), etc. near the arc due to arc heat.

Furthermore, in the past, the arc stuck in the gap space formed by the runner electrode and the arc-extinguishing plate for a long time until the AC breaking current reached zero, causing severe wear and damage to these materials. In order to reduce these damages, the area of the runner electrode and the slit gap were increased, but no current limiting effect could be expected.

The present invention eliminates abnormal wear of the runner electrode and at the same time reduces damage to the arc extinguishing plate due to arc heat.
The purpose is to improve the durability and current limiting performance of the current limiting device.

[Means for solving problems]

In the present invention, a resistive arc runner electrode is arranged along the outer circumference of one arc extinguishing plate, with half the circumference on the surface of the arc extinguishing plate and the remaining half circumference on the back side of the arc extinguishing plate. , a plurality of arc extinguishing plates arranged in a one-turn coil shape are provided in the vicinity of where an arc is generated, and each arc runner electrode is configured to short-circuit the pair of opening/closing contacts. They are connected so that each arc runner electrode has a solenoid shape.

〔Example〕

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

Fig. 1 is a longitudinal cross-sectional view showing the configuration of an embodiment of the present invention, Fig. 2 is an example of the configuration of the arc extinguishing section, Fig. 3 is an assembly diagram thereof, and Fig. 4 is a simplified diagram for explaining the operation. be.

In Fig. 1, runner electrodes 3 and 4 are provided in parallel above each of the fixed electrode 1 and the movable electrode 2, and between these runner electrodes 3 and 4, a 1-turn coiled runner electrode, which will be described later, is provided. did,
The arc-extinguishing section 6 is provided with multiple layers of arc-extinguishing plates.
The space formed by the multilayered arc extinguishing plates is defined as a slit, and this slit is wide near the electrodes and narrow at the tips of the runner electrodes 3 and 4 and the arc extinguishing part 6. ing. 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, and arc extinguishing part 6 other than the discharge port 9 with the insulating container 7, the space between the fixed electrode 1 and the movable electrode 2 and the The slit space is pressurized chamber 1
It is formed as 0. A fluid passage from this pressurization chamber 10 is connected to the atmosphere 11 via 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 the pressurization chamber 10 and the atmosphere 1
It also has a sealing effect between 1 and 2.

Next, the configuration of the arc extinguishing section, which is the main part of the present invention, will be explained. FIG. 2 is a part diagram of a set of arc-extinguishing plates constituting the arc-extinguishing section, in which a is a front view, b is a side sectional view taken along the - line in FIG. a, c is a plan view, and d is a bottom view.
In this figure, a resistive runner electrode is placed around the outer periphery of the arc-extinguishing plate 40, and half the circumference is on the surface of the arc-extinguishing plate like 20, and the remaining half of the circumference is on the back side of the arc-extinguishing plate 40 like 30. It is attached to. In addition, the part 2 where the runner electrode changes from the front surface to the back surface of the arc-extinguishing plate
3 are runner electrode protrusions 3a and 4a in FIG.
The setting is such that there is no electrical contact with the

In addition, the cross-sectional view on the - line side in FIG. It is wide near the arc-extinguishing plate and narrows toward the tip of the arc-extinguishing plate, and the discharge port 9 is at the end.

FIG. 3 is a diagram showing the set of arc-extinguishing plates shown in FIG. 2 assembled in multiple layers, and is a multi-layered version of the bottom view of FIG. 2 d. Electrical connections in this multi-layered arc-extinguishing section are made by connecting the end 25 of the runner electrode 20 and the end 35 of the runner electrode 30 in FIG. Connect the previous end 35, then connect the end 35 and the end 25 after it, repeat this for the number of stages, and the first part is the same as the fixed side runner electrode 3 in Fig. 1. The movable runner electrode 4 in FIG.
is connected to.

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 reaches the runner electrodes 3 and 4.
to move to. At this time, the current path is from the external terminal →
Fixed electrode 1 → Fixed side runner electrode 3 → Runner electrode protrusion 3a → Arc 8 → Runner electrode protrusion 4
a → Movable side runner electrode 4 → Current collector housing 5
A → External terminal. This current 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, and according to Fleming's left hand rule, the arc 8 tends to move upward in Figure 1. do.

Finally, the arc 8 comes into contact with the lower part 23 of the runner electrode attached to each arc-extinguishing plate, and the arc 8 is divided by each arc-extinguishing plate. The electromagnetic force causes the gap space 50 to move toward a narrower gap on the runner electrode attached to the arc-extinguishing plate. During the period from the generation of this arc until each segmented arc runs through the slit space, the pressure riser chamber 10
The gas is heated and its pressure increases.

Similarly, when the arc and the arc extinguishing plate come into contact, a portion of the wall of 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 pressurizing chamber 10 that is sealed from the atmosphere 11, and since a pressurizing chamber is not formed in a conventional air switch, no pressure increase can be expected.

This pressure increase, along with the electromagnetic force due to the magnetic field generated from the current path, also acts as a force to move the arc into the narrower gap in the upper part of FIG.

Next, as the divided arc moves to the narrower side of the slit, when the diameter of the arc moves to a gap length larger than the slit gap length, the arc closes between the pressurization chamber 10 and the discharge port 9. A blockage occurs. Due to blockage by this arc 8, the pressurization chamber 10
is completely sealed, and the pressure in the pressurizing chamber 10 increases more and more. This pressure increase causes the arc 8 to try to enter a narrower slit.

In addition, runner electrodes 3 and 4 resistive to the current path.
A part of the runner electrodes 20 and 30 attached to each arc extinguishing plate is inserted into the circuit, and the breaking current is limited as the arc moves, the diameter of the arc decreases, and the arc becomes easier to insert into narrow gaps. ing.

The above current path will be explained with reference to FIG. FIG. 4 shows only the runner electrodes mounted on each arc-extinguishing plate. Note that the arc-extinguishing plates sandwich each arc in FIG. 4 while forming a tapered gap, but this is not shown in the figure.

In FIG. 4, when each divided arc moves upward over the runner electrode 20 and the adjacent 30 mounted opposite to each other, the current path is a→b.
→ Arc → c → d → Lower part of runner electrode 23 → e
→ Arc → f → g → Lower part of runner electrode 23 → h
→ An arc...The shape becomes a solenoid, and an impedance z = √ ² + () ² is inserted into the circuit due to the pure resistance r of the resistive runner electrode and the reactance ωL of the solenoid. That means that.

By inserting impedance z into this circuit, the breaking current will be limited as the arc moves, the arc voltage of each broken arc will rise, and conversely, the arc resistance r _a will suddenly increase. begins to rise. When the commutation condition of r _a > r is established between this arc resistance r _a and the pure resistance r of the runner electrode, the breaking current will be caused by the extinguishment of the split arc that was previously flowing through each split arc. Then, the current is commutated to the runner electrodes attached to each arc-extinguishing plate. This commutation condition is such that as each divided arc in Figure 4 moves upward, the resistance of each runner electrode from b → a → b → c and e → c → d → f decreases. Since the total sum r also decreases, the r _a > r
These conditions are becoming more common. The factor that creates this condition is the impedance z to the circuit described above.
Needless to say, the increase in r _a is due to the insertion effect of the arc and the pressure increase in the pressurization chamber, and the insertion effect of the arc into the gap.

Next, when each divided arc disappears, the current path is a → a → b → d → lower part 23 of the runner electrode → c → d → g → lower part 23 of the runner electrode...
..., and the pure resistance component is the resistance component r of all the runner electrodes and the reactance component ωL formed by them (the area of the loop in the multi-stage solenoid becomes wider than in the case of an arc short circuit, increasing the reactance component) ), and the value of z also increases compared to when an arc exists, and as the value of z increases, the circuit breaking current is further limited.

〔Effect of the invention〕

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

A runner electrode that forms one turn of the arc-extinguishing plate is installed, and this is set up in multiple stages.
The overall configuration is solenoid-like, which is connected to the opening/closing contact in a short-circuit manner, and the slit space formed by the arc-extinguishing plate is tapered, with a discharge port provided at the tip, and a discharge port other than the discharge port. Since the configuration includes a booster chamber that covers all the parts, as the arc moves through the runner electrode, an impedance is inserted into the circuit, limiting the breaking current, and the pressure increase in the booster chamber due to arc heat further suppresses the arc. By inserting it into a narrow gap, it extinguishes the arc between the arc-extinguishing plates, creates an initial commutation condition that commutates the interrupting current to the runner electrode, and inserts impedance into the circuit to obtain a high current limiting effect. be able to.

As a result, wear of the runner electrode and further damage to the arc extinguishing plate caused by the conventional arc sticking phenomenon can be reduced, and the durability of the current limiting device can be improved and a high current limiting effect can be obtained.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view showing an embodiment of the present invention, Fig. 2
3 is a bottom view showing the arc-extinguishing plate assembled in multiple layers, FIG. 4 is a perspective view illustrating the current path according to the present invention, and FIG. 5 is a conventional one. FIG. 2 is a cross-sectional view showing the configuration of the device. 1: Fixed electrode, 2: Movable electrode, 3, 4: Runner electrode, 3a, 4a: Projection, 5: Current collector, 5
A: collector housing, 6: arc extinguishing section, 7: insulating container, 8: arc, 9: discharge port, 10: pressurization chamber,
11: Atmosphere.

Claims (1)

[Claims] 1. A current limiting device in which a pair of opening/closing contacts are disposed, and an arc generated by opening and closing of these contacts is transferred along a resistive arc runner electrode to limit a breaking current, For one arc-extinguishing plate, place a resistive arc runner electrode along the outer circumference of the arc-extinguishing plate so that half the circumference is on the surface of the arc-extinguishing plate and the other half is on the back side of the arc-extinguishing plate. , a plurality of arc-extinguishing plates configured by sequentially arranging these arc-extinguishing plates in the shape of a one-turn coil are arranged near where an arc is generated, and each arc runner electrode is connected to the pair of opening/closing contacts. 1. A current limiting device characterized in that the arc runner electrodes are connected in a short-circuited state and configured so that each arc runner electrode has a solenoid shape. 2. Leave the slit formed by the arc-extinguishing plate located farthest from the circuit contact as a discharge port, and seal the other components, such as the contact, arc-extinguishing plate, and arc runner electrode, with an insulating container. A current limiting device according to claim 1.