JPH07284217A - Connection part for high-voltage fireproof cable - Google Patents

Abstract

PURPOSE:To provide a connection part for a high-voltage fireproof cable with electric stability, by preventing a void in a fireproof layer or inside the layer. CONSTITUTION:A composite fireproof tape 14 is made of a mica tape 12' coated on one side with adhesive inorganic compound 13 of 1 to 3mm in a stiff and sticky state. A fireproof layer is formed by turning a composite fireproof tape 14 repeatedly with the side of the inorganic compound 13 put inward. The turned tapes are tightly jointed with the inorganic compound 13 in between when the fireproof layer is formed. As a result, the fireproof layer is snugly fitted to an uneven surface of the sleeve for connecting the conductor, and corona discharge and the like can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting portion of a 3.3 to 6.6 kV class high voltage fireproof cable.

[0002]

2. Description of the Related Art When providing a straight or branched type connecting portion in a fireproof cable used for an emergency circuit for fire fighting in a building, tunnel, etc., it is of course necessary to have fireproofing characteristics similar to those of the cable body. However, at the same time, it is indispensable to have stable electrical characteristics for a long period of time even in an emergency.

From the viewpoint of deterioration over time, particularly 3.3-
It is essential that the high-voltage fireproof cable used for 6.6kV does not generate corona during use.

Now, referring to the example of the straight connecting portion of FIG. 1, the connecting portion of the conventional high-voltage fireproof cable will be described. After connecting the conductors 2 and 2'with the sleeve 1, the glass mica tape (glass An inorganic material tape obtained by laminating mica powder on a fiber tape is wound to form a fire resistant insulating layer 3, and an insulating layer 4 such as polyethylene is formed on the fire resistant insulating layer 3 by tape winding or molding.

[0005]

Since the glass mica tape used in the connection portion of the above-mentioned conventional high-voltage fireproof cable is not stretched or elastic, the compressed connection sleeve 1 as shown in FIG. When it is wound around an uneven portion such as the surface of the tape, wrinkles and tape deviation easily occur, the tape does not fit on the conductor, and there is a gap 15 between the interface of the sleeve 1 and the tape 11 or between the tape winding layers.
Occurs. The void 15 becomes a factor that causes corona during the regular application of electric power, and there is a risk of causing aged deterioration of the insulator. In addition, the gap between the tape winding layers also causes a conductive gas generated when the insulator burns during a fire to enter the tape winding layers to reduce the insulation resistance.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and provide an electrically stable connection portion of a high-voltage fireproof cable.

[0007]

The connection portion of the high-voltage fireproof cable provided by the present invention comprises a fireproof insulating layer,
Use a composite fireproof tape with a layer of inorganic material compound having a clay-like adhesive strength on one side of glass mica tape applied to a thickness of 1 to 3 mm, so that this composite fireproof tape is on the inside of the inorganic material compound layer. Then, the fireproof insulating layer is formed by lap-winding. When the fireproof insulating layer is formed as described above, the layer of the inorganic material compound should be interposed between the winding layers of the tape and closely adhered to it, and should be well conformed to the uneven surface of the sleeve for connecting conductors and should be adhered without any gap. It is possible to eliminate the gap that causes corona generation.

Here, 1 to 3 layers of the inorganic material compound are used.
The reason why mm is used is as follows. That is, it is important for the fireproof insulating layer to have uniformity in thickness direction (insulating property, airtightness). In this case, the tape winding needs to be overlapped twice or more with 1/2 wrap. At this time, if the tape is too thin (compound layer is thin), local defects are likely to occur. Conversely, if it is too thick, the finished dimensions after lap winding will be too large, making it difficult to handle as a cable and from the installation space. Because it will be disadvantageous. From these points, a layer thickness of 1 to 3 mm was selected as a layer thickness that is stable in characteristics and has no problem in handling.

An inorganic compound having a clay-like adhesive strength at room temperature is based on silicone rubber, and contains mica powder to ensure insulation performance at high temperatures, and a silicate compound to suppress volume change. It is practical to add each of these to 150 parts by weight of the mica powder and the silicic acid compound per 100 parts by weight of the silicone rubber base material.
It is preferable that it is mixed with about 200 parts by weight. The mixing ratio is as shown in Table 1 for various samples.
It was found based on the results of a fire resistance evaluation test prescribed by the Fire Service Agency. The samples in Table 1 are 6.
Each sample was obtained by using a high-voltage fireproof cable for 6 kV and changing the composition in the layer of the inorganic compound compound in the composite fireproof tape of the fireproof insulating layer.

[0010]

[Table 1]

As is clear from Table 1, the inorganic compound has a good function as a fireproof insulating layer only when the amount of the mica powder and the silicate compound is 150 to 200 parts by weight based on 100 parts by weight of the silicone rubber base material. Therefore, even if the amount is less than 150 parts by weight or more than 200 parts by weight, the function of the fireproof insulating layer is unavoidably deteriorated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a connecting portion of a high-voltage fireproof cable to which the present invention is applied.
Reference numerals 2, 2'are conductors connected by the sleeve 1, 3 is a fireproof insulating layer, 4 is an insulating layer such as polyethylene, 5 is a semiconductive tape, 6 is a plated wire, 7 is a cable insulator, and 8 is a cable conductor. A fireproof insulating layer, 9 is a tape winding portion, and 10 is a cable sheath.

In this embodiment, the refractory insulating layer 3 is improved. That is, as shown in FIG.
A composite fireproof tape in which a layer 13 of an inorganic compound compound having excellent viscosity at room temperature is applied to a thickness of 1 to 3 mm on one side (upper side) of mica 11 'of a glass mica tape composed of 1'and glass tape 12' No. 14 is used, and the refractory insulating layer 3 is formed by stacking the inorganic compound layer 13 on the inside and stacking the layer 13 on the sleeve 1. The non-equipment compound 13 is based on silicone rubber, mixed with mica powder to ensure insulation performance at high temperatures, and with a silicic acid compound to keep volume change small. As described above, 150 to 200 parts by weight of the mica powder and the silicic acid compound are added to 100 parts by weight of the silicone rubber base material.
According to the inorganic material compound prepared as described above, stable electrical insulation is ensured at high temperature, and volume change is minimized by increasing the ratio of inorganic substances such as silicate compounds in an appropriate range. The generation of gaps and cracks can be suppressed.

FIG. 3 shows a modified example of the composite refractory tape improved according to the present invention. One side of the glass mica tape consisting of mica 11 "and glass tape 12" (on the lower side) is an inorganic material. It consists of a composite refractory tape 14 'with a layer of compound 13' applied.

[0015]

As described above, according to the connection portion of the high-voltage fireproof cable according to the present invention, the layer of the inorganic material compound having a clay-like adhesive force is formed on one surface of the glass mica tape in a thickness of 1 to 3 mm. Since the composite fireproof tape is applied to the conductor connection part so that the layer of the inorganic material compound is on the inside, the fireproof insulation layer is formed. The interface between the rugged surface of the sleeve and each other can be adhered without forming voids due to the adhesive force of the inorganic compound layer, which in turn causes corona generation due to voids or combustion during a fire. It is possible to suppress the invasion of the conductive gas containing carbon, which is contained in the tape, between the winding layers of the tape, and to provide an electrically stable cable of high pressure and fire resistance specifications. Door can be. Further, even if the surface to be coated is rich in undulations like a sleeve, the layer of the inorganic material compound having adhesiveness easily fits, so that workability can be improved in combination with the use of the composite fireproof tape.

Further, as a layer of the inorganic material compound of the composite refractory tape, based on silicone rubber, mica powder is used to secure the insulation performance at high temperature, and silicate compound is used to keep the volume change small. Using the one containing the above, the compounding in that case was made by adding 1 part of the mica powder and the silicate compound to 100 parts by weight of the silicone rubber base material.
By mixing 50 to 200 parts by weight, high insulation performance is exhibited at high temperature, volume change is suppressed small, and thickness of 1 to 3 mm is combined to prevent generation of defects such as cracks. be able to.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a connection portion of a high-voltage fireproof cable which is an object of the present invention.

2A and 2B are perspective explanatory views of a composite fireproof tape and FIG. 2B is an explanatory view of a winding state of the same tape according to an embodiment of the present invention.

FIG. 3 is a perspective explanatory view of a composite fire-resistant tape according to another embodiment of the present invention, and (B) is an explanatory view of a winding state of the tape.

FIG. 4 is a perspective view of a refractory tape as a conventional example, and FIG. 4B is an explanatory view of a winding state of the tape.

[Explanation of symbols]

 1 Sleeve 2, 2'Conductor 3 Fireproof Insulation Layer 4 Insulation Layer 5 Semiconductive Tape 6 Plating Wire 7 Cable Insulator 8 Cable Conductor Fireproof Insulation Layer 9 Tape Winding Section 10 Cable Sheath 11 ', 11 "Mica 12', 12 ″ Glass tape 13,13 ′ Layer of non-equipment compound 14,14 ′ Composite fireproof tape

Claims (2)

[Claims] 1. A high-pressure fireproof cable connecting portion in which a conductor connecting portion is sequentially provided with a fireproof insulating layer and an insulating layer, and as a fireproof insulating layer, an inorganic material compound having clay-like adhesive strength on one surface of a glass mica tape. Using a composite fire-resistant tape in which the layer of 1 to 3 mm is applied, and the fire-resistant insulating layer is formed by wrapping the composite fire-resistant tape so that the layer of the inorganic material compound is on the inside. High-voltage fireproof cable connection. 2. The connection portion of the high-voltage fireproof cable according to claim 1, wherein the inorganic material compound is a mixture of mica powder and 150 to 200 parts by weight of mica powder and 100 parts by weight of a silicone rubber base material. .