JPS62122016A - current limiting circuit breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air high pressure current limiting circuit breaker equipped with an arc-extinguishing plate.

[Conventional technology]

Figure 3 is a plan view of a conventional air high voltage current limiting circuit breaker, Figure 4 is a front sectional view taken along line A-A' in Figure 3, and Figure 5 is a cross-sectional view taken along line B-B' in Figure 4. FIG.

Their composition is as follows.

Arc runner electrodes (hereinafter referred to as "runner electrodes") 3 and 4 are provided in parallel above each of the fixed electrode I and the movable electrode 2, and an intermediate electrode 10 is arranged between these runner electrodes 3 and 4. There is. A current limiting resistive element (which may be a fuse) 11 is connected between this intermediate electrode 10 and one of the runner electrodes (runner electrode 3 in FIG. 3). The runner electrode 3.4 and the intermediate electrode 10 have protrusions 3'.

4' and 10', and these protruding parts are wide in the vicinity of the fixed electrode 1 and movable electrode 2 (Fig. 5), and narrow toward the tips of the runner electrodes and intermediate electrodes (g2). It is formed as shown in Figure 5).

The arc-extinguishing plate 6 is attached to sandwich the protrusions 3' and 10' and 10' and 4' from both sides, and the arc-extinguishing plate 6 and the protrusions 3' and 10' and 10' and 4' The width of the narrow gap near the electrode is wide <(g+), runner electrode 3.4
The tip of the intermediate electrode 10 is narrow (g2). The opening of this narrow gap g serves as the discharge port 9.

With the above configuration, the fixed electrode 1 and the movable electrode 2 other than the discharge port 9
By covering the runner electrodes 3, 4, intermediate electrode 10, and arc extinguishing plate 6 with an insulating container 7, the space between the fixed electrode 1 and the movable electrode 2 and the narrow space are formed as a pressurization chamber C. There is. A fluid passage from this pressurization chamber C passes through a discharge port 9 and enters the atmosphere.

The movable electrode 2 and the runner electrode 4 on the movable side are electrically connected by a current collector 5, and also provide a sealing effect between the pressurization chamber C and the atmosphere.

Next, the operation will be explained.

In a normal energized state, the fixed electrode 1 and the movable electrode 2 are in contact (although FIG. 4 shows an open state).

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 opening 2 of the movable electrode 2, becomes arcuate, and finally moves onto the protrusions 3' and 4' of the runner electrode 3.4 and the intermediate electrode 10.

The arc that comes into contact with this intermediate electrode 10 forms an electrode point on the intermediate electrode 10 and is separated. The current path at this time is: Fixed electrode 1 - Fixed side runner electrode 3 - Projection 3' → Arc 8 - Intermediate electrode projection 10 - Intermediate electrode 1 - Projection 10
'-arc 8'-movable runner electrode protrusion 4'-movable runner electrode 4-current collector 5-movable electrode 2, and the path has a convex shape, and the runner electrode 3,
The magnetic field generated by the current flowing through 4 acts perpendicularly to the arc current and, according to Fleming's left hand rule, the arc is subjected to an electromagnetic force that moves upward towards the narrower gap in FIG.

By the way, although this device is described in terms of electromagnetic force coming from a current path, a structure may also be used in which a coil is provided outside to apply a magnetic field that intersects at right angles to the arc.

The electromagnetic force causes the arc to move through the gap space toward a narrower gap. When the arc reaches a narrow gap with the same width as the diameter of the arc, the arc completely seals the pressurizing chamber C, so the pressure inside the pressurizing chamber rapidly rises due to gas expansion due to arc heat and melting and vaporization of the arc extinguishing plate. .

Due to this electromagnetic force and the pressure in the pressurization chamber C, the arc is forced into a narrower slit space. The arc resistance in the arc extinguishing chamber of the current limiting section increases rapidly, and when it exceeds the resistance value of the current limiting resistor 11, the commutation arc 8 in FIG.
It flows out into l. At this time, the current path is fixed electrode 1 - fixed side runner electrode 3 - current limiting resistor 11 ... intermediate electrode 10
- intermediate electrode protrusion 10' - arc 8' - movable runner electrode protrusion 4' - movable runner electrode 4 - current collector 5 - movable electrode 2. That is, the current limiting resistor 11 is inserted into the circuit, and the circuit current is significantly limited.

Next, the arc 8 in the disconnection section arc extinguishing chamber in this current limited state
' is cut off at the zero point of the alternating current. However, direct current is interrupted under conditions of slit interruption performance.

As the arc-extinguishing plate 6 of the above current limiting circuit breaker, the present inventors have used silicon nitrogen and SiAlON (registered trademark), a composite of silicon nitrogen and alumina.

This ceramic was chosen because, as shown in Table 1, it has the best thermal shock resistance, mechanical strength, and electrical insulation. Thermal shock resistance in Table 1 refers to ceramic materials that are heated to high temperatures, dropped into water, and subjected to a bending test. Refers to temperature. Therefore, it can be said that the higher the temperature, the higher the heat resistance strength.

Table 1 According to experiments conducted by the present inventors, alumina ceramics cracked at the current limiting part and the interrupting part when interrupting the arc in the low current range even with an 8 fl thick arc extinguishing plate. The surface of zirconia ceramics is noticeably melted by the arc in the current limiting section and the interrupting section, and especially in the current limiting section, molten debris fills the slits, and the arc resistance does not increase and commutation to the current limiting resistor element 11 does not occur. That's the result. On the other hand, SiAlON ceramics, which is a composite material of nitrogen silicon and nitrogen silicon and alumina, which has high thermal shock resistance and is difficult to break even under the heat of the arc, was not damaged by the arc, although there was some discoloration due to the arc in the current limiting and disconnecting sections.

However, in a region where the breaking current was large, the surface of the nitrogen-silicon ceramic in the disconnection section was caused by arc heat to form wrinkle-like uneven surfaces in a direction perpendicular to the direction of the arc.

Furthermore, as a result of analyzing the uneven surface that appeared on the surface as arc traces using an X-ray diffraction device, it was found that Si units were precipitated in addition to β-5izNa, which is the main component of nitrogen-silicon ceramics, and these arc traces Conductive parts were observed. A similar phenomenon also occurred in Sialon ceramics.

[Problem that the invention seeks to solve]

As a result, as short circuits are repeatedly interrupted, the insulating performance of the surfaces of these ceramics is extremely reduced, and the short circuit current cannot be cut off at the disconnection point, resulting in a re-ignition phenomenon. In addition, only the portion of the current-limiting portion that was in contact with the arc was discolored, and wrinkle-like uneven surfaces did not occur as in the disconnecting portion, and the insulation did not deteriorate. This is because the arc inserted into the slit of the arc-extinguishing plate in the current limiting section increases as the slit gets narrower, and when it reaches a value greater than the current limiting resistance element, the arc is immediately commutated to the resistance element. This is because the arc within the slit disappears and the arc does not stick at a certain location. However, since the arc in the disconnection section sticks together within the gap, it is thought that the damage will be significant.

This has been the biggest hurdle in increasing the capacity (larger current, higher voltage) of slit current limiting devices and, ultimately, in putting them into practical use.

[Means for Solving the Problems] ``In order to solve the above problems, the present invention provides a method that has excellent arc extinguishing performance as a disconnecting arc that narrows the intermediate runner electrode of a conventional slit current limiting circuit breaker, and has a short circuit current. The arc-extinguishing plate is made of asbestos/alumina-phosphate composite ceramics that will not crack or deteriorate insulation due to arc heat.

[Effect]

With the above configuration, the current limiting performance is improved in the commutation section 2 and the arc extinguishing performance is improved in the disconnection section [Examples] The present invention will be specifically described below based on Examples. That is, in the present invention, as shown in FIG.
6 is made of asbestos-alumina-phosphate composite ceramics with excellent arc-extinguishing performance, such as Alhotite (registered trademark) ceramics, and the commutation section arc-extinguishing plate 6 is made of nitride-based ceramics with excellent current-limiting performance. did. Other configurations and operations are the same as before.

Table 2 shows the current limiting performance and arc extinguishing performance of each ceramic. Here, current limiting performance is when a short circuit current flows through the circuit breaker, and is the time integral value of the square of the current that flows when an arc is inserted into the ceramic slit. An example is shown in FIG. In this figure, the horizontal axis represents time, and the vertical axis represents arc current and voltage. Arc-extinguishing performance is compared based on the magnitude of the residual current that flows after the current reaches zero point in the AC circuit breaker.

Table 2 From this table, the current limiting performance is as follows: nitrogen silicon>alumina>zirconia>alphotite. On the other hand, zirconia has poor arc-extinguishing performance, and the other three types have almost the same performance.

Therefore, when used as a disconnection section, alphotite ceramics will not deteriorate insulation due to arc heat like nitrogen silicon and sialon, and because it is a composite material with fibrous materials such as asbestos, it is resistant to thermal shock. There is no risk of cracking like alumina ceramics, and there is no large residual current like zirconia. Therefore, it can be used repeatedly many times.

〔Effect of the invention〕

As described above, according to the present invention, by using an alphotite ceramic arc-extinguishing material in the disconnecting section of a slit current limiting commutation type circuit breaker that includes a current limiting section and a disconnecting section, it is possible to replace the conventional silicon nitride or sialon ceramics. This eliminates the molten conductive irregularities on the surface caused by arcs, which leads to poor insulation and eliminates the re-ignition of the short-circuit breaking current. I was able to figure it out.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of the current limiting circuit breaker according to the present invention, and FIG. 2 is a graph showing the relationship between arc current and voltage during arc interruption.
Figure 3 is a plan view of a conventional current limiting circuit breaker, Figure 4 is a front cross-sectional view taken along line A-A' in Figure 3, and Figure 5 is B-B in Figure 4.
FIG. l: Fixed electrode 2; Movable electrode 3: Fixed side arc runner electrode 4: Movable side arc runner electrode 5: Current collector 6: Arc extinguishing plate 7: Container 8: Arc 9: Discharge port lO: Intermediate electrode 11: Current limiting resistor Element 16: Arc extinguishing plate

Claims (1)

[Claims] 1. A separable fixed electrode and a movable electrode are arranged, an arc runner electrode is provided in parallel on each electrode, and a pair of arc extinguishing plates are placed between the electrodes so as to sandwich the arc runner electrode. A slit is formed that gradually narrows from the tip of the arc runner electrode to the tip of the arc runner electrode, and the narrowest slit between the arc runner electrode and the tip of the arc extinguishing plate is used as a discharge port. By covering the fixed electrode, movable electrode, arc runner electrode, and arc extinguishing plate with an insulating container, the electrode space and the gap space become a pressurizing chamber for gas due to arc heat, and the gap space becomes a pressurization chamber for gas due to arc heat. In a current limiting device that uses a gas pressurization chamber and closes a slit space with arc heat, an intermediate electrode is provided between the pair of arc runner electrodes, and a gap between the intermediate electrode and the arc runner electrode on the fixed electrode side is provided. A nitride-based ceramic arc-extinguishing plate with excellent current-limiting performance is provided, and a current-limiting resistor element is connected between these electrodes. A current-limiting circuit breaker characterized in that an asbestos/alumina orthophosphate ceramic arc-extinguishing plate with excellent arc-extinguishing performance is provided between the electrodes as a disconnecting section.