JPH033937Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Field of Industrial Application) The present invention relates to improvement of the fireproof layer of fireproof electric wires. (Problems to be solved by conventional techniques and ideas) Conventionally, fire-resistant electric wires have been made using single-sided glass mica tape, which is a layered layer of glass cloth tape and laminated mica tape, on a conductor as a fire-resistant layer, or a polyolefin film on one or both sides. It was constructed by winding mica tape (hereinafter simply referred to as mica tape) as a reinforcing layer, and sequentially covering it with an insulating coating made of polyethylene or the like and a sheath made of polyvinyl chloride or the like. However, when a single-sided glass mica tape was applied, there was a drawback that the insulation resistance of the glass cloth tape decreased at high temperatures. Furthermore, when mica tape is used, the fire resistance is improved compared to the single-sided glass mica tape, but the ionic gas generated when the insulation coating or sheath is burned penetrates into the mica foil, reducing the electrical properties. It had drawbacks. In order to compensate for this, it is necessary to increase the number of turns of the mica tape, which increases the outer diameter and weight of the cable, and has disadvantages in terms of cost and administration. (Means for Solving the Problem) The present invention provides a fire-resistant electric wire in which a fire-resistant layer is provided on a conductor. It is characterized by consisting of a wound layer. (Example) The present invention will be described below based on the drawings of one example. In FIG. 1, for example, three insulated wire cores 4 whose outer periphery is coated with a fireproof layer 2 and an insulating layer 3 made of polyolefin, etc. are arranged in a substantially circular shape together with a paper inclusion 5, and on the outside of this is a restraining layer. 6 and a polyvinyl chloride sheath layer 7 are sequentially provided. As shown in FIG. 2, the fireproof layer 2 includes, for example, a composite mica tape 8 made of laminated mica scales impregnated with a heat-resistant synthetic resin, a silica gel-containing layer 9 made of finely powdered silica gel dispersed in silicone rubber or silicone varnish, and polyolefin. It is formed by winding a composite tape in which tapes 10 are laminated. Here, if the composite tape is wound in multiple layers, the fire resistance performance will be further improved. Next, an example of the present invention will be described. Example 1 As a fireproof layer of a 600V, CV cross-linked polyethylene insulated vinyl sheathed power cable, a composite tape made by laminating a composite mica tape layer, a silica gel-containing resin layer made of silicone rubber and silica gel, and polyethylene tape was wound with the polyethylene tape side inside. are twisted into 7 cores to produce a fire-resistant electric wire, and this fire-resistant electric wire is made in accordance with Fire and Disaster Management Agency Notification No. 7.
Heat it from room temperature to 840℃ for 30 minutes, hold it at 840℃, measure the electrical insulation resistance just before 30 minutes after starting heating and the dielectric breakdown voltage immediately after heating, and display the results. Shown below. Example 2 The silica gel-containing resin layer of the fireproof layer of Example 1 was changed to one in which silica gel was dispersed in silicone varnish, and tests were conducted on the same structure except for the silica gel-containing resin layer, and the results are shown in the table. Conventional Example 1 Tests were conducted on the same structure as in Example 1 except that the fireproof layer was replaced with a single-sided glass mica tape, and the results are shown in the table. Conventional Example 2 Tests were conducted on the same structure as in Example 1 except that the fireproof layer was replaced with a single-sided film mica tape, and the results are shown in the table. Conventional Example 3 The fireproof layer consists of a composite mica tape layer, a silica gel-containing resin layer made of silicone rubber and silica gel,
A test was conducted on a composite tape in which a glass cloth tape layer was laminated and integrated, but otherwise the same as in Example 1. The results are shown in the table.

[Table] Just before reaching the point.
As described above, the ionic gas adsorption effect of silica gel, which is stable even at high temperatures, prevents gas from entering the mica foil, allowing the characteristics of mica to be fully exhibited and lowering the insulation resistance value and withstand voltage value. Furthermore, unlike glass film, it does not deteriorate its electrical properties even under high temperatures during combustion. (Effects of the invention) As is clear from the above examples, according to the invention, fine powder silica gel is interposed in the insulating tape of laminated mica tape and polyolefin tape as a fireproof layer, so that sufficient electrical properties are achieved even at high temperatures. Therefore, the fire resistance properties can be improved without increasing the number of windings of the mica tape.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the fireproof electric wire according to the present invention.
FIG. 2 is a cross-sectional view of the refractory layer of the electric wire of the present invention. 2... Fireproof layer, 8... Laminated mica tape, 9...
...Silica gel-containing layer, 10...Composite tape.

Claims (1)

[Scope of utility model registration request] A fire-resistant wire comprising a fire-resistant layer provided on a conductor, wherein the fire-resistant layer is comprised of a wound layer of a composite insulating tape in which finely powdered silica gel is interposed between a composite mica tape and a polyolefin tape. .