JPH0621326U - Fireproof bus duct - Google Patents

Abstract

(57) [Summary] [Purpose] Even if exposed to high temperatures such as fire, it withstands long-term use. [Structure] A conductor 1 is covered with a fireproof layer 2 of mica, and the outside thereof is covered with a conductor insulator layer 3 in which silicone rubber containing aluminum oxide powder is reinforced with glass fiber.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a fire-resistant bus duct, and more particularly to a fire-resistant bus duct whose conductor insulation layer has performance exceeding the standards set forth by the Fire Service Agency.

[0002]

[Prior art]

 In recent years, it has become possible to secure an emergency power source to enable emergency evacuation warnings and indoor broadcasting even in the event of a fire. Bus ducts have been used. A conventional refractory type bus duct, for example, as shown in the cross-sectional view in FIG. 1, has an electrical conductor and a fireproof layer 2 on its outer periphery wound with a laminated mica tape as an electrical insulation layer 3 on its outer periphery. A fire-resistant bus duct is constructed by winding an organic material such as polypropylene or cross-linked polyethylene or a tape such as silicone rubber, and winding this in duct 4. (JIS C 8364)

There is a notification from the Fire Service Agency regarding the performance of the above fire resistant bus duct. That is, the standard is to raise the temperature from room temperature to 840 ° C for 30 minutes in the combustion furnace specified in the above notification in the course of 30 minutes, while maintaining the withstand voltage of 600 V and the insulation resistance of 0.4 MΩ or more. That is, it is required that a voltage of 1500 V is applied for 1 minute immediately after the temperature in the furnace reaches 840 ° C to prevent dielectric breakdown.

[0004]

[Problems to be solved by the device]

 As the conductor insulation layer 3 of the fireproof bus duct, a fireproof bus duct made of an organic material such as polypropylene or cross-linked polyethylene is heated from room temperature to 840 ° C for 30 minutes based on the fireproof test announced by the Fire Service Agency. The inside of the shaped bus duct is in a state of oxygen-diluted state, which is close to being sealed, and organic materials such as polypropylene and cross-linked polyethylene are carbonized and decomposed into carbides and soot, which are formed in the refractory layer 2 and duct 4. It adheres to the side surface to reduce the insulation resistance between each conductor and between the conductor and the duct.

A refractory bus duct using silicone rubber for the conductor insulation layer 3 has a small amount of carbon in the molecular structure of the silicone rubber, and therefore has a small amount of carbonization. Insulation resistance drops less than those of fire resistant bus ducts that use organic materials. However, since the tensile strength of silicone rubber is weaker than that of other organic materials, it breaks when rolled from above the refractory layer 2 during processing, and due to the large elongation, it stretches and becomes uneven, resulting in uniform insulation. Since it is difficult to form the thickness, the insulation performance will vary. Furthermore, since silicone rubber is expensive, it also has a large impact on the cost of fire-resistant bus ducts.

The present invention has been made in view of the above points, and an object of the present invention is to provide a low-cost fire-resistant bus duct having excellent heat-resistant insulation.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the fire-resistant bus duct of the present invention has a refractory layer formed on the outer circumference of a conductor, and a conductor insulating layer formed on the outer circumference of the refractory layer. As the conductor insulator layer, a layer made of silicone rubber reinforced with electrically insulating artificial mineral fibers is used.

The conductor conducts electricity, and a well-known conductor made of copper or a copper alloy, which is a good conductor of electricity, is used. For example, a rod-shaped member having a rectangular cross section is usually used, but a rod-shaped member having various shapes such as a quadrangle, an ellipse, and a circle, or a tubular member having these cross-sectional shapes is used. Used.

The refractory layer is for performing heat insulation and electrical insulation in a high heat atmosphere at the time of fire, and is formed as a laminated body by winding a mica tape having heat resistant insulation properties so as to cover the outer circumference of the conductor. Let As the tape, for example, peeled mica tape or laminated mica tape in which peeled mica or laminated mica is impregnated with silicone varnish and glass woven cloth, plastic film or the like is bonded as a reinforcing material with silicone varnish is used.

As an electrically insulating artificial mineral fiber that reinforces the silicone rubber of the conductor insulation layer, glass fiber, rock wool, mineral wool having an insulation resistance of 10 ⁵ MΩ or more and a tensile strength of 50 kg / mm ² or more, Ceramic fibers, silica fibers, silicon nitride fibers, etc. are used. These fibers are used as short fibers containing cotton having a thickness of about 1 μm to 100 μm, preferably 2 to 80 μm, and a length of about 0.1 to 10 cm, or as long fibers having a length of 10 cm or more.

The reinforcing method for the silicone rubber is a method of mixing single fibers, thread-shaped or string-shaped short fibers before the silicone rubber is solidified. The mixing amount was 0. It may be appropriately selected from the range of 1 to 3 weight ratio. Alternatively, one or two or more layers of the bundled fibers, filament-like or string-like long fibers woven or knitted into a cloth, non-woven fabric, or a net-like material may be immersed in the silicone rubber before the silicone solidifies. how to. Alternatively, it may be performed by impregnating woven cloth, non-woven cloth, reticulated cloth, etc. with silicone rubber before solidification.

The conductor insulating layer is formed by adhering a layer of silicone rubber reinforced with artificial mineral fibers to a predetermined thickness on the outer periphery of the refractory layer. It is preferable that a knitted cloth, a net-like material, etc., impregnated with silicone rubber and formed into a tape shape are wound around the outer periphery of the refractory layer to form a laminated body. Alternatively, a woven fabric, a non-woven fabric, a knitted fabric, a net-like fabric or the like made of artificial mineral fibers may be impregnated with silicone rubber to form a tubular form, and the tubular form may be covered and formed.

Further, electrically insulating inorganic powder such as aluminum oxide, magnesium oxide, mica, silicon nitride, boron nitride, aluminum hydroxide and magnesium hydroxide can be added to the silicone rubber. When mica is added, the insulating property is improved, and when hydroxide is used, carbonization of coexisting organic substances is prevented. It is preferable that the particle size of the inorganic powder is small, but normally, a particle size of 0.1 to 100 μm is used. The addition amount may be selected from the range of 0.01 to 2 relative to 1 of silicone rubber.

[0014]

【Example】

 In FIG. 1, 1 is a conductor, 2 is a refractory layer of an assembled mica tape, 3 is a conductor insulating layer, and a silicone rubber composite tape 5 containing glass fiber woven cloth and aluminum oxide powder in silicone rubber. , It is formed by winding it while wrapping it on the refractory layer 2 so that it overlaps by 2/3 width. 4 is a steel sheet duct.

Further, the silicone rubber composite tape 5 has a configuration shown in FIG. 2 as a schematic enlarged view. In FIG. 2, 6 is silicone rubber, 7 is glass fiber, and 8 is aluminum oxide powder.

Next, in order to compare the performance of the insulation resistance test between the embodiment of the present invention and the conventional example, the fire resistant bus duct A according to the present invention and the fire resistant bus ducts B and C of the conventional example are described below. It was produced in this way.

[0017]

[Preparation of fire-resistant bus duct A of the present invention]

 The silicone rubber composite tape 5 is obtained by impregnating 100 parts by weight of silicone rubber with 60 parts by weight of aluminum oxide powder, and impregnating the silicone rubber with a glass fiber woven cloth having a thickness of 0.2 mm to a content of about 60%. , It was heated in a dryer. Then, the laminated mica tape was wound around the whole surface of the conductor 1 made of a copper plate having a thickness of about 6 mm, a width of about 150 mm and a length of about 2 m by a vertical wrap 6 times to form a refractory layer 2 and then formed. The silicone rubber composite tape 5 was wrapped on the refractory layer of No. 2 by 2/3 width and wound once to form the conductor insulator layer 3.

In this way, three bus bars having the fire-resistant layer 2 and the conductor insulating layer 3 provided on the conductor 1 were prepared, and they were stacked in the width direction as shown in FIG. I put it inside. Then, one more duct 4 was produced in the same manner as described above, and two of these were connected to produce a fireproof bus duct having a length of about 4 m.

[0019]

[Preparation of fire resistant bus duct B of the conventional example]

 The refractory bus duct B is formed of a conductor insulation layer 3 by winding a polypropylene film having a thickness of 0.06 mm 5 times with a 2/3 width lap, instead of the silicone rubber composite tape 5 in the refractory bus duct A. Except for the above, it was manufactured in the same manner as the fire-resistant bus duct A.

[0020]

[Preparation of conventional fire-resistant bus duct C]

 The refractory bus duct C was produced in the same manner as the refractory bus duct A, except that a silicone rubber tape having a thickness of 0.3 mm was used instead of the silicone rubber composite tape 5 in the refractory bus duct A.

The fireproof bus duct A (hereinafter abbreviated as bus duct A) according to the present invention thus obtained and the fireproof bus ducts B and C (hereinafter simply referred to as bus duct B and bus duct C) of the conventional example are The electrical insulation performance during heating was examined. In the electrical insulation performance test, heating was performed from normal temperature to 840 ° C. for 30 minutes according to the heating temperature curve of JIS A 1304. Immediately after reaching 840 ℃, a voltage of 600V was applied between the conductors 1, 1 ', 1 "and between the conductors 1, 1', 1" and the duct 4 during the heating. The insulation resistance was measured, and then a voltage of 1500 V was applied for 1 minute to examine the withstand voltage. The results of the above electrical insulation performance test are shown in Table 1.

[0022]

[Table 1]

In Table 1, the term “during heating” means that the temperature in the furnace reaches 840 ° C. after the start of heating, and the term “after heating” means immediately after the temperature reaches 840 ° C. In addition, the standard is a fire resistance certification standard that has been established and announced by the Fire Service Agency.

As is clear from Table 1, the insulation resistance has characteristics of G standard or higher, but the bus duct A has 8 to 15 MΩ between conductors and 4 to 8 MΩ between conductor and duct. B is 1 to 3 MΩ between conductors, 0.6 to 1.5 MΩ between conductors and ducts, and Bus duct C is 2 to 5 MΩ between conductors and 0.8 to 2 MΩ between conductors. I understand.

The tape breakage or elongation, which is one of the causes of the deterioration of the insulation performance of the fireproof bus duct, is caused by the load applied during processing. Therefore, the tensile strength of the silicone rubber composite tape (hereinafter abbreviated as tape A) used for the bus duct A according to the present invention and the silicone rubber tape (hereinafter abbreviated as tape C) used for the conventional example as the duct duct C was tested. It was The obtained results are shown in Table 2.

[0026]

[Table 2]

The tape width of each sample in Table 2 was 5 mm. As is clear from Table 2, the tensile strength of Tape A is 12 times that of Tape C. Therefore, when forming the conductor insulation layer, the present invention has a winding speed of about 30% compared to silicone rubber tape. % Can be improved.

[0028]

[Effect of device]

 In the fireproof bus duct of the present invention, the conductor insulation layer is formed of silicone rubber reinforced with electrically insulating artificial mineral fibers, or silicone rubber in which inorganic powder is further added to the reinforced silicone rubber. Therefore, since the cost is low, the electrical insulation of the conductor insulation layer is excellent, and the reinforcing material with high tensile strength is used, the winding speed can be increased and the productivity is improved. Furthermore, when using an inorganic powder having excellent insulating properties at high temperatures or an inorganic powder that prevents carbonization of organic substances, the heat resistant insulating property can be further improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of a refractory bus duct according to the related art and the present invention.

FIG. 2 is a schematic enlarged cross-sectional view of an example of the silicone rubber composite tape used in the examples.

[Explanation of symbols]

 1, 1 ', 1 "…… Conductor 2 …………………… Fireproof layer 3 …………………… Conductor insulator layer 4 …………………… Duct 5 ………… ………… Silicone rubber composite tape 6 …………………… Silicone rubber 7 …………………… Glass fiber 8 …………………… Aluminum oxide powder

Claims (3)

[Scope of utility model registration request] 1. An electric conductor (1), a fireproof layer (2) covering the outer periphery of the conductor (1), a conductor insulating layer (3) covering the fireproof layer (2), and these are housed. A refractory bus duct comprising a duct (4), wherein the conductor insulation layer (3) is composed of silicone rubber reinforced with electrically insulating artificial mineral fibers. 2. The fireproof bus duct according to claim 1, wherein the conductor insulator layer (3) is a laminate formed by winding a tape-shaped silicone rubber reinforced with electrically insulating artificial mineral fibers. . 3. The refractory bus duct according to claim 1, wherein the artificial mineral fiber is glass fiber.