JPS6293823A - Insulated nozzle for gas 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 [Technical Field to which the Invention Pertains] This invention is directed to introducing compressed gas into a separation gap formed between a fixed contact and a movable contact of a circuit breaker. The present invention relates to a method of improving the arc resistance of an insulating nozzle made of an insulating material, which is provided with a spouting opening and contributes to extinguishing the arc generated in the separation gap, from the viewpoint of the material.

[Prior art and its problems]

First, as a gas circuit breaker equipped with this type of insulating nozzle, damage to the insulating nozzle in a buffer shadow type circuit breaker using arc-extinguishing gas F6 gas will be explained.

FIG. 3 shows an example of the structure of a buffer type gas circuit breaker equipped with such an insulating nozzle, and when shutting off, a driving device (not shown) moves the insulating rod 16 and the current-carrying tube 14 in the direction of the arrow. It concentrically surrounds a tulip-shaped movable contact 6 which is integrally attached to a buffer cylinder 11 driven by the buffer cylinder 11, and an opening lower a is provided through which a rod-shaped fixed contact 5 disposed coaxially with the movable contact enters and exits. The provided insulating nozzle 7 is attached to the buffer cylinder 11 using a retaining ring 8, and the figure shows the circuit breaker in a closed state. The current flowing from the terminal 2a of the bushing conductor 2b, the fixed base 4. Fixed contact 5. Movable contactor 61 energizing cylinder 14, current collector 15. Bushing conductor 3b
It flows out from the terminal 3a of the other bushing 3 through.

When the buffer cylinder 11 is driven to the right in the figure, the gas compressed in the buffer chamber 13 passes through the ring-shaped gap formed between the movable contact 6 and the insulating nozzle 7 in the axial direction. However, it is guided to the separation gap formed between the fixed contact 5 and the movable contact 6. As the opening stroke progresses and the position shown in the lower half of Figure 4 is reached, the compressed gas passes through the opening lower a and is ejected as shown by arrow P, causing an arc due to the adiabatic expansion effect of the compressed gas. The outer circumferential side of the arc begins to be strongly cooled, while the arc thins itself to reduce the cooling surface area and prevent heat from being taken away.As a result, the current density in the arc increases and the temperature of the arc core increases significantly. The vicinity of the opening of the insulating nozzle surrounding the arc whose temperature has increased in this manner receives strong radiant energy from the arc core. The wavelength of the radiation that makes up the radiant energy is widely distributed from heat rays in the infrared region to visible light rays to the far ultraviolet region. , penetrates into the interior from the nozzle surface to a depth of about 10 to 100 m, and thermally decomposes or carbonizes the resin at this depth, and turns it into dust or gas. On the other hand, insulating nozzles are made by compressing and molding fluororesin powder, heating and firing it, so air is contained in the insulating nozzle9, and this air is pyrolyzed, carbonized or gasified as described above. This causes cracks to appear on the nozzle surface, or part of the nozzle surface to peel off.
It ends up falling off. In this way, when the inside becomes carbonized or the surface peels off, the dielectric strength of the insulating nozzle decreases, or the gas flow on the nozzle surface becomes turbulent, resulting in a decrease in the breaking performance of the circuit breaker.

In order to eliminate such drawbacks of insulating nozzles made of a single fluororesin, for example, Japanese Patent Publication No. 53-2863
As disclosed in No. 9, inorganic fillers such as bronze, metals such as copper, iron, and lead, metal oxides such as silicon oxide, titanium oxide, and aluminum oxide, glass fiber, fluorite, clay, talc, etc. , each particle size is 3~20μ
An insulating nozzle is known in which the insulating nozzle is made of a fluororesin mixed with a large amount of filling amount of 10 to 80% by volume.

In other words, radiant energy easily causes thermal decomposition, carbonization,
By mixing in a large amount of material that does not undergo gasification and is difficult for radiation to pass through, it is possible to block radiation from entering the nozzle and improve the internal arc resistance of the nozzle.

However, according to experiments conducted by the inventors of the present invention, when a fluororesin insulator containing a large amount of the above-mentioned metals or metal oxides is used as a nozzle material, the withstand voltage performance decreases and the mechanical strength decreases. The result was that the deterioration was severe 2, and that the material did not exhibit sufficient performance as a material for an insulating nozzle used in a MET device. This is because a large amount of metals and metal oxides are mixed in, so the adhesion between the mixed metals and metal oxides and the fluororesin is poor, resulting in a decrease in mechanical strength and withstand voltage performance. It is something.

[Purpose of the invention]

The present invention provides fluorine containing a filler that is less consumed by tartness and peeling, and has less deterioration in mechanical strength and withstand voltage performance, even if the metals and metal oxides are not mixed in large quantities. The purpose is to provide an insulating nozzle made of resin.

[Key points of the invention]

This invention uses compressed gas in the gap formed between the fixed contact and the movable contact of the circuit breaker. In an insulating nozzle made of an insulating material, the insulating nozzle is provided with an opening for guiding the compressed gas and ejecting the compressed gas, thereby contributing to extinguishing the arc generated in the separation gap. The above objective is achieved by constructing the fluororesin with increased fluororesin.

[Embodiments of the invention]

Figures 1 and 2 show an insulated nozzle made of fluororesin mixed with fine particles of boron nitride, and a conventional insulated nozzle made of fluororesin mixed with fine particles of metal oxide and other substances. The results of a comparative test are shown for the insulating nozzle made of a single fluororesin and no filler mixed therein.

As shown in FIG. 1, as an example of the mixing ratio of phosphorus nitride image particles in a fluororesin into which borosilicate nitride image particles are mixed, the mixing ratio is set to a small weight ratio of 5 cm. In the comparative products mixed with metal oxides and other fine particles, the types of fillers were aluminum oxide and a double salt consisting of calcium carbonate and magnesium carbonate, and the mixing ratio was four times that of the above example. All types of fluororesin are tetrafluoroethylene resin. Even in the case of fluororesin that does not contain fillers, the type of fluororesin is ethylene tetrafluoride resin, which is in accordance with @3 parties. Furthermore, the firing conditions were the same for both the Examples and the Comparative Examples.

Figure 2 shows the results of a comparative test for the former four.The mechanical strength, that is, the tensile strength, which is the most important for an insulated nozzle that is subjected to internal pressure, is that of the example of Comparative Example 1.
,2 shows an increase in strength of 50 cm. Since the amount of boron nitrided in the examples was as small as only 5%, the strength was naturally comparable to that of the fluororesin alone (Comparative Example 3).

Further, regarding the penetration breakdown voltage, the strength of the example was 3 times that of Comparative Example 1, and 1.6 times that of Comparative Example 2. Moreover, when the short circuit current is 10 kA and the arc time is 10 ms,
While the nozzle opening inner diameter widened by 9 when shut off 0 times, no widening was observed between the example and comparative example 3, which was a remarkable difference from comparative example 1.2. In addition, as a result of visual observation of the nozzle surface subjected to arc heat, no abnormality was observed in the example and comparative example 1.2, clearly demonstrating the effect of the filler. Carbonized conductive paths, cranks, and peeling just before falling off were observed on the nearby surface and inside.

According to the test results, the particle size of the fluorine nitride image particles used in the present invention is such that, if the mixing ratio is the same, the smaller the particle size, the less thermal decomposition, carbonization, or gasification of the fluororesin. This effect becomes noticeable when the thickness is 5 μm or less. In addition, the mechanical strength and voltage resistance characteristics decrease from the values of the fluororesin alone as the mixing ratio increases, but the upper limit of the mixing ratio that can substantially maintain these values is approximately 30% by weight. %. In addition, thermal decomposition occurred under the cutoff conditions shown in FIG.

It was confirmed that the lower limit of the mixing rate that can effectively reduce carbonization or gasification is about 3 when the average particle size is 5 μm.

Therefore, by varying the particle size and the mixing rate independently or in conjunction with each other according to the thermal, mechanical, and electrical properties required of the circuit breaker based on the circuit breaker rating,
It is possible to obtain the optimum nozzle according to the characteristics of the circuit breaker.

Further, as the fluororesin used in the present invention, in addition to tetrafluoroethylene resin, fluororesins such as a copolymer of tetrafluoroethylene resin and hexafluoroethylene resin and fluoroethylene propylene can be mentioned.

〔Effect of the invention〕

As mentioned above, is the insulating nozzle of a gas circuit breaker made of fluororesin mixed with borosilicate nitride particles? = 5, then
Even if the mixing rate of boron nitride image particles is low, thermal decomposition, carbonization, and gasification inside the nozzle can be effectively reduced, and since the mixing rate is small, fluororesin The effect is that the high insulating properties and mechanical strength possessed by the single body can be substantially maintained.

[Brief explanation of drawings]

Figure 1 is a comparison table from the material aspect of insulating nozzles tested to see the effects of the present invention, categorized by type of filler, mixing rate, and type of fluororesin. A performance comparison table showing the mechanical, electrical, and thermal characteristics of each insulating nozzle, and FIG. 3 is a sectional view showing the structure of a gas circuit breaker having an insulating nozzle to which the present invention is applied.
The fourth figure is an enlarged sectional view of the vicinity of the opening of the insulating nozzle to explain the thermal influence of the arc on the insulating nozzle. 5... Fixed contact, 6... Movable contact, 7... Insulated nozzle, 7a... Opening.

Claims (1)

[Scope of Claims] 1) An opening is provided for introducing compressed gas into a gap formed between a fixed contact and a movable contact of a circuit breaker and for spouting out the compressed gas. An insulating nozzle made of an insulating material that contributes to extinguishing an arc caused by a gas, characterized in that the insulating nozzle is made of a fluorine resin mixed with boron nitride fine particles to increase arc resistance. Insulating nozzle of circuit breaker. 2) A gas circuit breaker characterized in that the amount of boron nitride fine particles mixed into the fluororesin in the insulating nozzle according to claim 1 is 3 to 30% of the weight including the fluororesin. Insulated nozzle. 3) In the insulating nozzle according to claim 1,
The particle size of the boron nitride fine particles mixed into the fluororesin is 5μ.
An insulating nozzle for a gas circuit breaker, characterized in that the nozzle is less than m.