JPH0447623A - Buffer type gas breaker - Google Patents

Abstract

PURPOSE:To make it possible to suppress the degradation of insulating strength and breaking characteristics to the lowest level by manufacturing a nozzle, which is composed of tetrafluoroethylene filled with silicon carbide or silicon carbide and boron nitride, by means of sintering the silicon carbide, which is manufactured in the form of super-micro-particle beta-silicon carbide through a CVD method, in the Ar gas coexisting with a extremely small amount of N2. CONSTITUTION:A nozzle 1 is composed of tetrafluoroethylene particles 3 filled with silicon carbide particles 2. The silicon carbide particles 2 which are fabricated in the form of super-micro-particle beta-silicon carbide by a CVD method are sintered in the Ar gas coexisting with an extremely small amount of N2, and at that time, a flow ratio of the N2 gas in the Ar gas is less than 1 volume % and the sintering temperature is 2000 deg.C or higher. When the nozzle 1 is irradiated by arc energy 4, a part of the energy becomes reflection arc energy 5 on the surface and is not incident inside of the nozzle, only a part of the energy penetrates the inside of nozzle. Accordingly, the invading arc energy 6 is diffused quickly because the silicon carbide particles 2 have high thermal conductivity, and the heat does not concentrate locally.

Description

[Detailed description of the invention] [Object of the invention] (Field of application in industry-1-) The present invention relates to a puffer type gas circuit breaker,
In particular, it relates to a puffer type gas circuit breaker whose nozzle has improved arc resistance.

(Prior art) A gas circuit breaker that has a fixed contact and a movable contact that can be moved in and out of a container filled with an arc-extinguishing gas such as S I"6 gas performs an operation to cut off current. An arc occurs between the fixed and movable contacts.

In order to extinguish this arc, the puffer type gas circuit breaker is equipped with a puffer chamber consisting of a puffer piston and a puffer cylinder in the movable contact section, and compresses the arc-extinguishing gas by compressing the puffer chamber. This is a circuit breaker configured to direct the arc to a nozzle and spray it on the arc generated between the fixed and movable contacts.

Conventionally, an insulating nozzle made of fluororesin has been used as a nozzle for such a puffer type gas circuit breaker. However, when an insulator made of fluororesin is exposed to an arc, the energy radiated from the arc penetrates into the fluororesin and is absorbed, causing voids or carbonization inside the nozzle, which impairs insulation performance. This results in a significant decrease in interest and a loss of nostle interest. As a result, as the interruption operation is repeated, the nozzle deteriorates, and the state of the gas flow blown out from the nozzle becomes significantly different from the initial preferable state, which may cause a decrease in dielectric strength and interruption performance.

In order to prevent such nozzle deterioration, for example, in Japanese Patent Publication No. 49-17654, 0.1 to 50% by weight of alumina powder is uniformly dispersed in tetrafluoroethylene resin to prevent arc energy from flowing inside the nozzle. We have obtained a tetrafluoroethylene resin composition that blocks the intrusion and has excellent arc resistance.

Furthermore, Japanese Patent Publication No. 53-28216 proposes a resin composition which has excellent anti-scratch properties in a wide sense of the term, using the expression that an inorganic filler is mixed into a fluororesin. Although there are differences in expression, it is said that even if the energy rays generated from the arc enter the nozzle, they will not be concentrated locally, and therefore will not cause carbonization, cracks, etc., and will not deteriorate insulation performance. .

Since then, many fillers have been studied, and it is naturally expected that the effect will be greatly influenced by the type of filler.

(Problem to be Solved by the Invention) However, although the conventional method of filling fluororesin with alumina powder etc. as described above has the effect of blocking arc energy, the gas If the arc energy increases more than the current level in the future due to the increase in the capacity of the circuit breaker, there will be a limit to its effectiveness, and there is a risk that the dielectric strength and breaking performance, which are important functions of the nozzle, will deteriorate.

The present invention was proposed to solve the problems of the prior art as described in -1- below, and its purpose is to reduce arc energy in the future by increasing the capacity of gas circuit breakers, which has been progressing in recent years. Even when the current equipment size increases, the energy generated from the arc can be quickly diffused, and the decline in dielectric strength and breaking performance can be minimized. An object of the present invention is to provide a puffer type gas shutoff device.

Another purpose is to shield more than 30% of the energy generated from the arc to reduce the energy that enters the nozzle, thereby minimizing deterioration in nozzle performance.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, in the puffer type gas circuit breaker of the present invention, the nozzle is made of silicon carbide or tetrafluoroethylene filled with silicon carbide and boron nitride. configure,
In addition, this silicon carbide is made into ultrafine β-silicon carbide produced by the CVD method, and is characterized in that it is produced by sintering it in Ar gas IJ in which a trace amount of N2 gas coexists.

Furthermore, in the sintering of silicon carbide, the flow rate ratio is 1-1 in Ar gas.
In a gas coexisting with N2 gas of less than % by volume, 2
It is desirable to carry out the sintering at a temperature of 000°C or higher.

(Function) By adopting the above configuration, the puffer type gas circuit breaker of the present invention can quickly diffuse the arc energy absorbed in the nozzle, thereby improving dielectric strength and interrupting when exposed to arc. This makes it possible to minimize deterioration in performance.

Especially 5. When the nozzle is made of tetrafluoroethylene filled with silicon carbide and boron nitride, most of the energy generated from the arc can be shielded by boron nitride, so the energy entering the nozzle can be significantly reduced. This makes it possible to minimize deterioration in nozzle performance.

(Example) Hereinafter, the configuration of an example of the puffer type gas circuit breaker according to the present invention will be explained using FIGS. 1-2.

Furthermore, Figures 1 and 2 are schematic diagrams showing the particle structure inside the nozzle and the traveling path of the incident arc energy. The first example and FIG. 2 show a second example in which tetrafluoroethylene particles are filled with silicon carbide particles and silicon nitride particles.
An example is shown.

First, in a first embodiment shown in FIG. 1, a nozzle 1- of a puffer type gas circuit breaker is composed of tetrafluoroethylene particles 3 filled with silicon carbide particles 2. The silicon carbide particles 2 are ultrafine β-silicon carbide produced by CVD according to the claims of the present invention, and are sintered in A, r gas with a very small amount of N2 present. and the flow rate ratio of N2 gas in Ar gas when sintering the silicon carbide particles 2 is 1-vol% or less, and the sintering temperature is 2000°
It is configured such that C or more is 1-.

The operation of the first embodiment having the configuration as described in 1- above is as follows.

That is, as shown in FIG. 1, when the nozzle 1- is irradiated with arc energy 4, a part of the incident arc energy 4 is reflected (shielded) on the nozzle surface, becomes reflected arc energy 5, and is ejected from the nozzle. Only a part of the arc energy (intrusion arc energy) 6 does not enter the inside of the nozzle.

Here, the silicon carbide particles 2 of this example are ultrafine β-silicon carbide produced by the CVD method, and are produced by sintering in Ar gas with a very small amount of N2 present. Therefore, the relationship between the sintering conditions (flow rate ratio of N2 gas in Ar gas and sintering temperature) and density can be found in the Journal of the Institute of Electrical Engineers of Japan, Vol. 1-09, No. 11 (November 1989). As shown in Figure 5 in "Development of new SiC ceramics with high thermal conductivity and insulation properties" (Morinobu Endo, Yoshinobu Sugihira, Nobuaki Urasato, Il Hayashi, chapter 1) on page 481, and furthermore, in this example, As such, if the silicon carbide particles 2 are sintered in a gas where the flow rate ratio of N2 gas in Ar gas is 1% by volume or less and at a sintering temperature of 2000°C or higher, The density is about 2. 8 (g/c
m3) or more.

In this way, the density is 2. The thermal conductivity of silicon carbide, which exceeds 8 (g/cm3), is approximately 80 (W/mK) or higher, as shown in Figure 12 of the above paper, and as shown in the same figure, It exhibits a thermal conductivity that exceeds that of silicon carbide manufactured using conventional methods. Therefore, the intruding ac energy 6 that has entered the inside of the nozzle 1 of this embodiment is quickly diffused due to the high thermal conductivity of the silicon carbide particles 2, and the heat is not concentrated locally.

Due to the action described in 1- above, the puffer type gas circuit breaker of the first embodiment can quickly diffuse the arc energy absorbed by the nozzle 1, which improves the dielectric strength and breaking performance when exposed to scum. It becomes possible to suppress the decrease to a minimum.

In addition, in the second embodiment shown in FIG. 2, the nozzle 1 of the puffer type gas circuit breaker is the same as described above except that the tetrafluoroethylene particles 3 are filled with boron nitride particles 7 in addition to the silicon carbide particles 2. The configuration is similar to that of the first embodiment.

In the second embodiment, since most of the arc energy can be shielded by the boron nitride particles 7, the amount of arc energy that enters the nozzle 1 can be significantly reduced, thereby minimizing the performance deterioration of the nozzle 1. This makes it possible to suppress this to a minimum. As in the first embodiment, the minute amount of arc energy absorbed by the nozzle 1 is quickly diffused by the silicon carbide particles 2, so that the dielectric strength and breaking performance are prevented from deteriorating when exposed to the arc. It becomes possible to suppress it to the minimum.

[Effects of the Invention] As described above, in the puffer type gas circuit breaker of the present invention, the nozzle is made of silicon carbide or tetrafluoroethylene filled with silicon carbide and boron nitride, and the silicon carbide is made of silicon carbide by CVD. Manufactured ultrafine β-
By manufacturing silicon carbide and sintering it under certain conditions, even if the arc energy increases by 1- in the future due to the increase in the capacity of gas circuit breakers that has been progressing in recent years, it will be able to withstand arcing. It is possible to provide a puffer-type gas circuit breaker equipped with an excellent nozzle that can quickly diffuse the generated energy and minimize deterioration in dielectric strength and interrupting performance.

In particular, when the nozzle is made of tetrafluoroethylene filled with silicon carbide and boron nitride, boron nitride can more effectively shield the energy generated from the arc, reducing the amount of energy that enters the nozzle. ,
This makes it possible to minimize deterioration in nozzle performance.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams showing different embodiments of the puffer type gas circuit breaker according to the present invention, and both are schematic diagrams showing the particle structure inside the nozzle and the traveling path of the incident arc energy. ]-... Nozzle, 2... Silicon carbide particles, 3... Tetrafluoroethylene particles, 4... Incident arc energy, 5
... Reflected arc energy, 6... Penetrating arc energy, 7... Boron nitride particles. ] 2

Claims (2)

[Claims] (1) A container filled with arc-extinguishing gas has a fixed contact and a movable contact that can be moved in and out, and a puffer chamber consisting of a puffer piston and a puffer cylinder provided in the movable contact is compressed. In a puffer-type gas circuit breaker having an arc-extinguishing chamber that compresses arc-extinguishing gas and guides it to a nozzle and extinguishes the arc generated between the fixed and movable contacts, the nozzle is made of silicon carbide. Or, it is composed of tetrafluoroethylene filled with silicon carbide and boron nitride, and this silicon carbide is ultrafine β-silicon carbide produced by CVD method, and Ar with a trace amount of N_2 gas coexisting. A puffer-type gas circuit breaker characterized in that it is manufactured by sintering in gas. (2) When silicon carbide is present in a gas consisting of Ar gas and N_2 gas at a flow rate ratio of 1% by volume or less,
The puffer type gas circuit breaker according to claim 1, characterized in that it is manufactured by sintering at a sintering temperature of 0.degree. C. or higher.