JPS5924481B2 - arcuate sleeve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a complex-shaped arc chute pre-cut device used as an arc extinguishing device for an air heater, disconnector, air contactor, or the like.

Generally, arc chute fronts are used to cool arcs that occur when electrical circuits are interrupted, and these arc chute fronts are made of porcelain or zircon refractories mixed with asbestos.

However, the above-mentioned porcelain arc chute has low arc resistance, and its running path is considerably eroded and eroded by large currents, resulting in a short service life.

In addition, the arc chute of zircon-based refractories mixed with asbestos has a relatively low maximum thermal breakage current, but the mixed asbestos generates dust that is harmful to the human body during manufacturing, and large amounts of expensive zircon are used, making it unavoidable. However, the disadvantage was that the cost was high. The present invention has been made in order to eliminate the above-mentioned drawbacks, and aims to provide an arc chute pre-heater that can cool, reliably cut, and extinguish a high-output arc using refractory raw materials that are harmless to the human body and relatively inexpensive. It is.

The present invention will be explained in detail below.

The arc shoot prep of the present invention contains, by weight, 30 to 50% of cordierite powder, 10 to 30% of refractory material powder containing 60% or more of alumina powder, and 10 to 35% of zircon powder.
It is characterized by being formed by molding and firing a mixed raw material consisting of 10 to 20% alumina cement powder.

The reason why the blending ratio of cordierite in the refractory raw material is limited to the above range in the present invention is that when the amount of cordierite is less than 30% by weight, the obtained arc chute has excellent thermal shock resistance and high frequency insulation resistance. On the other hand, if the amount exceeds 50% by weight, the fire resistance before arc shoot corrosion will decrease.

The reason for limiting the blending ratio of the refractory material containing 60% or more alumina to the above range is that if the amount of the refractory material is less than 10% by weight, the fire resistance before arc shoot corrosion will decrease; This is because if the weight percentage is exceeded, the sintering properties will be lowered and only an arc shoot material with poor density will be obtained. Examples of such refractory materials containing 60% or more of alumina include synthetic mullite, sintered mullite, fused mullite, sintered alumina, and fused alumina. Furthermore, the reason why the blending ratio of zircon was limited to the above range is that if the amount of zircon is less than 10% by weight, a high current arc cutting effect cannot be expected, whereas if the amount exceeds 35% by weight, This is because not only cannot the effect of cutting off a high current arc be expected, but also the cost is high.

Furthermore, the reason why the blending ratio of alumina cement is limited to the above range is that if the amount of alumina cement is less than 10% by weight, the bondability and sinterability of the obtained arc shoot mantle will decrease; This is because if it exceeds 20% by weight, the expandability increases, leading to a decrease in thermal shock resistance.

Next, a manufacturing method for producing an arc shoot sleeve according to the present invention will be explained by showing an example. 1. After casting and demolding the refractory raw material powder having the above-mentioned composition in a mold, the resulting molded body is fired at a temperature of 1000° C. to 1400° C. to produce an arc shoot sleeve.

2 Water is added to the granular refractory raw material having the above-mentioned composition to form a slurry, which is molded into a silicon rubber mold by vibration casting.The mold is then dried under constant temperature and humidity, and then the mold is The molded body removed from the mold was heated to 1000℃~1400℃.
The arc chute sleeve is made by firing at a temperature of ℃.

Of the above methods, by particularly employing method 2, it is possible to obtain an arc chute sleeve with excellent dimensional accuracy and surface smoothness, and which is highly effective in interrupting and extinguishing arcs.

Therefore, the arc shoot sleeve of the present invention is made of cordierite, which has low expansion, can withstand thermal shock due to rapid heating and cooling, and has low dielectric loss and excellent high frequency insulation properties, and cordierite, which has high fire resistance and excellent spalling resistance. It is made of a refractory material containing over 60% alumina, zircon with good arc resistance, and alumina cement with high bonding and sintering properties, and is harmless to the human body because each component is blended in a predetermined ratio. It is available at a relatively low price, is dense, has fire resistance, anti-sboring properties,
It has excellent arc resistance and can reliably break and extinguish arcs that occur due to large currents.

Examples of the present invention will be described below. Example: 16% by weight of water was added to a granular refractory raw material having the composition ratio shown below to form a slurry, which was vibration-cast using a silicone rubber mold (vibration width: 0.3m0). It was dried for 24 hours in an atmosphere of 10° C. and 75% humidity.

After drying and demolding, the molded body is fired at a temperature of 1000°C to produce two arc shoot substrates 1 having a plurality of teeth on the soil surface as shown in FIG.
The teeth and the grooves between the teeth were fitted together to obtain the arc shoot mantle 2. The arc shoot sleeve obtained from the granular refractory raw material has a fire resistance (SK) of 14, a porosity of 24.5%, a bending strength of 100K7/CTil, a compressive strength of 300K7/C-Til, and a coefficient of thermal expansion of 0.35% (σT).
20 to 1000°C).

In addition, the arc shoot mantle of the above embodiment, the porcelain arc shoot mantle (Comparative Example 1), and the asbestos-zircon artashute mantle (Comparative Example 2) were attached to a high-pressure air contactor, and JEM ( Japan Electrical Manufacturers Association standards)
1167 was used to investigate the shear cut-off current.

Short circuit and break conditions Voltage: 6.9 KV Current: 4.4 KA Power factor: 0.3 Takashi: open - open after 2 minutes of closing As a result, the breaking limit current of the arc shoot sleeve of the present invention is as high as 5200 A. On the other hand, that of Comparative Example 1 is 460
The value of 0A1 Comparative Example 2 was as low as 4800A.

Furthermore, when the arc chute sleeves of the present invention and Comparative Examples 1 and 2 were attached to a high-pressure air contactor, the contactor reached 6.9K.
A load of V, 400A was intermittently opened and closed 100,000 times.

The average arc time from opening to extinction of the contactor was determined from the number of cycles. As a result, the contactors equipped with the arcshute sleeves of Comparative Examples 1 and 2 took a long time, 2.3 cycles and 2.0 cycles, respectively, whereas the contactors equipped with the arcshute sleeve of the present invention took 1.3 cycles. It was confirmed that the cycle was as short as 3, and the damage to the intersection of the teeth of the arc chute tube was small, resulting in a life span of 3 to 4 times longer than that of Comparative Examples 1 and 2. As described in detail above, according to the present invention, it is harmless to the human body, can be obtained at a relatively low cost, is dense, fire-resistant,
It has excellent spalling resistance and arc resistance, and can quickly cool and reliably break arcs generated from large current breakers.
It is possible to eliminate it and extend its useful life.
It has remarkable effects such as being suitable for use as an arc extinguishing device for air vents, disconnectors, air contactors, etc.

[Brief explanation of the drawing]

The figures are perspective views showing one form of the arc-shute mantle of the present invention, FIG. 1 is a partial view of the arc-shute mantle, and FIG. 2 is an overall view of the arc-shute mantle into which the arc-shute substrate of FIG. 1 is fitted. be. 1, 1'...Arc shoot board, 2...
...Arcshoot mantle.

Claims (1)

[Claims] 1 Cordierite powder 30-50% by weight,
10-30% refractory material powder containing 50% or more alumina, 10-35% zircon powder, and 10% alumina cement powder.
An arc chute sleeve characterized by being formed by molding and firing a mixed raw material consisting of ~20%.