JPS5819776Y2 - flame retardant electrical cable - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to improving the flame retardancy of a flame-retardant electric cable incorporating an insulated wire core.

Conventional methods to further improve the flame retardancy of flame-retardant electric cables include making the flame-retardant sheath layer a material with a higher oxygen index, and making the insulating layer a flame-retardant material. One or more of the above methods have been applied depending on the usage conditions of the cable, such as making the inclusions a flame-retardant material and making the tape wrapping layer a flame-retardant material. However, increasing the flame retardancy of materials as described above or using many flame retardant materials has problems in terms of economic efficiency and practicality, as it leads to a decrease in cost and performance in terms of mechanical properties.

The present invention was devised as a result of various studies in view of the above drawbacks, and in a flame-retardant electric cable with a built-in insulated wire core, cellulose is used on the insulated wire core, on the twisted insulated wire core, or on both. The present invention provides a flame-retardant electric cable characterized in that the tape made of woven fabric is repeatedly ramped several times so that the thickness of the tape winding layer becomes 0.3 rran or more.

The present invention will be explained below using the drawings.

FIG. 1 is a cross-sectional view showing one embodiment of the flame-retardant electric cable of the present invention, in which a tape-wrapped layer 2 made of cellulose-based woven fabric is provided on an insulated wire core 1, with an intervening material 3 interposed therebetween. Three fibers are twisted together, and on top of that, a pressure tape wrapping layer, a shielding layer, etc. (not shown) are provided, and an ordinary flame-retardant sheath layer 4 is provided on the outside thereof.

FIG. 2 is a cross-sectional view showing another embodiment, in which three insulated wire cores 1 are twisted together with an inclusion 3 interposed therebetween, and a holding tape wrapping layer, a shielding layer, etc. are provided thereon (not shown). Further, a tape-wrapped layer 2 made of a cellulose-based woven fabric is provided thereon, and an ordinary flame-retardant sheath layer 4 is provided on the outside thereof.

Further, FIG. 3 is a cross-sectional view showing still another embodiment,
Tape-wrapped layer 2 made of cellulose-based woven fabric on insulated wire core 1
Three fibers are twisted together with an intervening material 3 interposed therebetween, and on top of that, a presser tape wrapping layer and a shielding layer (not shown) are provided, and on top of that, a tape wrapping layer 2 made of cellulose-based woven fabric and its outer side are formed. A normal flame-retardant sheath layer 4 is provided on the top.

The constituent materials of the insulated wire core 1, the inclusion 3, and the flame-retardant sheath layer 4 used in the present invention are not limited at all in the present invention.

Further, a holding tape wrapping layer, an electrical shielding layer, etc., which are generally used in electric cables, can be provided at appropriate locations.

As the cellulose yarn woven fabric, it is possible to use a cotton fabric such as a canvas, or a cotton fabric treated with a flame retardant rubber coating or a silicone rubber coating.

In the present invention, the tape winding layer 2 is formed by repeatedly ramping the cellulose yarn woven fabric tape several times, and
．． It is necessary to make it 3Mn or more.

The reason for this is that, as is clear from the following experimental examples, flame retardancy is not improved when the tape is formed by one simping winding, regardless of the thickness of the cellulose yarn woven tape used.

Even if the thickness of the tape used is thin, it can be wrapped in multiple layers with 2 pumps.
．． It may be 3 mm or more.

If the number of wrapping layers is 0.3 rrrrn or more, it is preferable that the number of wrapping layers is larger.

I'm not sure what effect this is due to, but when the cable fire spreads, the cellulose thread woven tape winding layer carbonizes or further ashes, but when the cable is wrapped in multi-layer wrapping, this carbonization or ashing occurs. It is thought that the insulator of the insulated wire core wrapped in this layer is prevented from melting and dripping, thereby preventing combustion and fire spread.

However, in the case of one-time simping winding, even if it is carbonized or incinerated, it does not become a dense and durable layer, so it is considered that the above-mentioned effect does not exist.

The present invention will be explained below using experimental examples.

Table 1 shows the results of the experimental examples, and Materials 1 to 3 are
Materials 4 to 8 are experimental examples of the cable of the present invention, and are experimental examples of comparative cables.

The cables used in the experimental examples were 3000V three-core CV cables having the configurations shown in FIGS. 1, 2, and 3, and the tape-wrapped layer 2 was made of cotton fabric. As for the structure, Document 1 is a layer made by repeating the ramping of cotton tape twice to make the layer 0.3 mm thick, Document 2 is a layer made by repeating the ramping of cotton tape twice to make the layer 0.4 mm thick, Document 3 Material 4 is the layer made by repeating the ramping of the cotton cloth tape twice to make the layer 0.5 mm thick, Document 4 is the layer made by repeating the ramping of the cotton cloth tape twice to make the layer 0.25 mm thick, and Document 5 is the layer made of the cotton cloth tape made to be 0.25 mm thick. Material 6 was wrapped once with cotton tape and the layer was 0.3 mm thick. Material 7 was wrapped with cotton tape once and the layer was 0.3 mm thick. Layer with 0.4 body thickness and document 8
The cotton cloth tape was ramped once to make the layer 0.5M thick.

The above experimental method involves placing the experimental cables of Materials 1 to 8 on a tray in a combustion test device with a tact length of 10 m, and burning the cables with a fire source of up to 360.00 ob, t, u/hr. An experiment was conducted using the so-called vertical closed duct combustion test method, and the test was evaluated as a failure if the cable spread to the top of the 10m tray.
Less than 0m was considered to be a pass.

The results are shown below.

As is clear from the above experimental results, in the case of cables in which the thickness of the tape winding layer of Samples 5 to 8 is made up of one simping, the layer collapses due to fire, and even if the flame spreads and the thickness is increased, it will not respond accordingly. The flame retardant effect is not exhibited.

On the other hand, in the case of the cables in which the tape winding layer thickness of Samples 1 to 3 is made up of twice-run pink, if the thickness is 0.3y+m+ or more, the flame retardant effect will be exhibited without the layer being destroyed by the flame, and the more the thickness increases, the more the thickness will increase. It was noticeable.

However, Sample 4 did not pass the above test method because the thickness was insufficient even after wrapping twice, so the layer was destroyed by the flame, the insulating layer was ignited, and the flame expanded.

Although a 300V three-core CV cable was used as the experimental cable, it goes without saying that the flame retardant effect would be improved if vV cable, EV cable, etc. were used in the same manner.

As described above, the cable of the present invention can be made flame-retardant by simply applying multiple turns of woven cellulose tape of 0.3 mm or more on the insulated wire core, on the twisted insulated wire core, or on both. It is possible to reduce the use of highly flame-retardant materials and the use of large amounts of flame-retardant materials, which has been done in the past, reducing costs and reducing the performance of mechanical properties. It has advantages such as prevention.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are cross-sectional views of a flame-retardant electric cable according to an embodiment of the present invention. 1: Insulated wire core, 2: Tape winding layer, 3: Inclusions, 4: Flame-retardant sheath layer.

Claims (1)

[Scope of utility model registration request] In a flame-retardant electric cable with a built-in insulated wire core, the tape is wound by repeatedly ramping a tape made of cellulose-based fabric over the insulated wire core, over the twisted insulated wire cores, or both. A flame-retardant electric cable characterized by having a layer thickness of 0.3 mm or more.