JPH0722007Y2 - High voltage fire resistant wire - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage fire-resistant electric wire useful when used for internal wiring of a building or the like.

[0002]

2. Description of the Related Art In recent years, fire protection measures have been emphasized as buildings have become higher in height, and in order to minimize damage during a fire, disaster prevention equipment such as fire fighting equipment and evacuation equipment in the early stages of a fire 3.3 to 6.6 kV that can be energized for 30 minutes or more
High-voltage fireproof electric wire is used. Conventionally, as a high-voltage fire-resistant electric wire used for such a purpose, as shown in FIG. 1, a winding layer of mica tape (having a thickness of 0.1
2 mm, 1/2 lap winding 15 layers) is provided, and a cross-linked polyethylene insulating layer 3 and a shielding layer 4 are provided on the fire-resistant layer 2 in the same manner as a general cross-linked polyethylene insulated vinyl sheath cable (hereinafter referred to as CV cable). Further, a so-called internal fire-resistant layer type high-voltage fire-resistant electric wire is known, on which a fire-resistant protective layer 5 formed of a 1/2 lap winding of glass cloth tape and a flame-retardant vinyl sheath 6 are applied. However, in the case of the internal fire-resistant layer type high-voltage fire-resistant wire having such a structure, when the mica tape winding layer is directly extrusion-coated with the cross-linked polyethylene and the cross-linked polyethylene is cross-linked, the mica is subjected to the vapor pressure (about 15 kg / cm ² ) at the time of cross-linking. Wrinkles were generated in the tape winding layer, and there was a problem that part of the mica tape bites into the crosslinked polyethylene insulating layer 3. In addition, there is a drawback that the mica tape winding layer on the conductor 1 becomes a factor for promoting the growth of the water tree. That is, in recent years, the high-voltage fire-resistant wire is used not only as an emergency power supply but also as a common power supply. In many cases, this wire is used for a long time in a high humidity environment. And, the micro protrusions of the mica layer of the mica tape and the gap between this layer and the cross-linked polyethylene insulation layer are the origin of the water tree development, and naturally the problem of the water tree encountered in general CV cables is highlighted. become. Further, in such a structure, there is a drawback that the cost is high because many expensive mica tapes are wound.

For this reason, as shown in FIG.
A so-called external fire-resistant layer type high-voltage fire-resistant electric wire in which an external fire-resistant layer 8 and a protective jacket 9 are provided on the cable 7 has been developed. Since it is formed by winding an inorganic tape such as asbestos tape, its mechanical strength is inferior to that of general materials, and it is easily damaged when laying electric wires or when inspecting cable lines during use. In addition, since a large number of inorganic tapes are wound, the number of winding steps of the inorganic tapes is increased, which is inevitably expensive.

[0004]

The present invention has been made in view of such a point, and there is no fear that a water tree will be generated in the cross-linked polyethylene insulating layer, and the cable line when laying or using the electric wire. The purpose is to provide an inexpensive high-voltage fire-resistant electric wire that is not likely to be damaged at the time of inspection.

The high-voltage fireproof electric wire of the present invention has a heat-absorbing layer consisting of a cross-linked polyethylene insulating layer and a wound layer of a tape containing aluminum hydroxide and a foaming agent on the sheath of the cable body having a sheath on the outside thereof. Providing a refractory fireproof layer,
A heat insulating fire resistant layer consisting of a wound layer of epoxy glass cloth or flame retardant paper is provided on the heat absorbing fire resistant layer, and a jacket made of flame retardant polyvinyl chloride is further provided on the heat insulating fire resistant layer. It is characterized by being formed.

[0006]

In the high-voltage fireproof electric wire of the present invention, the outermost layer has a jacket made of flame-retardant polyvinyl chloride. Therefore, when a fire occurs, first, the flame-retardant polyvinyl chloride is burned to form a carbonized layer. This carbonized layer can prevent the heat insulating refractory layer existing inside the jacket from directly contacting the flame. Also, due to the heat insulating effect of the heat insulating fire resistant layer, heat transfer to the inside of the cable is delayed, and then the heat absorbing chemical reaction that occurs due to the heat of the heat absorbing fire resistant layer inside the heat insulating fire resistant layer causes the cable body to enter the cable body. It is possible to delay the transfer of heat.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings of an embodiment. In FIG. 3, the high-voltage fireproof electric wire according to the present invention is
General cross-linked polyethylene insulated vinyl sheath cable (below
Below, it is called "CV cable". ) Cable body
10, the heat-absorbing fireproof layer 11 provided on the sheath of the cable body 10, the heat-insulating fireproof layer 12 provided on the outer periphery of the heat-absorbing fireproof layer 11, and the heat-resistant fireproof layer 12 provided on the outer periphery of the heat-resistant fireproof layer 12. And a jacket layer 13 made of flammable polyvinyl chloride. Endothermic refractory layer 11
Is formed by a winding layer of a tape containing aluminum hydroxide and a foaming agent, which will be described later, and the heat-insulating fireproof layer 12 is formed by a winding layer of epoxy glass cloth or flame-retardant paper, which will be described later. By the way, the outer refractory layer of the high-voltage fire-resistant electric wire has a large (a) thermal insulation property against the heat applied from the outside during a fire (in the standard fire curve according to JIS A1304, the temperature is raised to 840 ° C. in 30 minutes), Do not transfer heat from the outside to the internal insulator as much as possible, (b) Maintain the shape as a refractory layer when heating from the outside (do not cause cracks, dripping, or other phenomena that promote heat transfer to the internal cable). ) And (c) In the chemical reaction or phase change caused by heating,
Basic performance is required such that these reactions or phase changes are endothermic (latent) heat type (preventing temperature rise of internal cable). Therefore, the present inventors conducted a selection test of various materials by the test method described later in order to evaluate the above three performances. First, a test method for comparing heat insulation characteristics will be described. As shown in Figure 4, diameter 70m
A sample 15 is placed on a copper disc 14 having a thickness of 10 mm and a thickness of 10 mm, and is heated by a Bunsen burner 16 from the lower side. In the figure, 19 indicates 500 g of refractory brick. Table 1 shows the measurement results of various materials when tested by the above test method.

[0008]

[Table 1] From Table 1, as factors contributing to the heat insulation effect, in addition to the physical thermal conductivity, the distance from the copper disk (heat source) is increased (decreased) by foaming or thermal softening during heating. It can be seen that the effect of such a shape change considerably contributes, but the details thereof will be described later.

Next, the results of investigation of endothermic properties of various materials by differential thermal analysis (hereinafter referred to as DTA) will be described. Here, DTA means that when a substance causes a chemical reaction such as a phase change such as dissolution or evaporation caused by heating or cooling, or a thermal decomposition, as shown in FIG. This is one method of detecting energy changes such as heat generation. As an external refractory layer of high-voltage fireproof wire, these materials endothermic reaction during heating, that is,
Those exhibiting a behavior of reducing heat transfer to the inside are desirable. As shown in FIG. 6, the DTA curve 20 contains the reference material 21 and the sample 22 in the electric furnace 20, and
It is obtained by increasing the temperature of. That is,
When a temperature difference is generated between the reference substance 21 and the sample 22, the difference is D through the thermocouples 23 and 24 arranged at the lower position of both.
It is introduced into the TA circuit unit 25, and its output is recorded in the recorder 26.

FIG. 5 shows an example of measurement of the DTA curve with a frame seal. For comparison of heat absorption of materials (samples), a base line 27 is drawn as indicated by a dotted line, and the heat absorption with this base line 27 is made. The area S surrounded by the DTA curve 20 on the side is obtained, and the size of the area S is relatively compared. That is, a material having a large area S indicates that the material has excellent heat absorption, and a material having a small area S has a small heat absorption property. In the figure, 28 indicates a weight change curve and 29 indicates a furnace temperature. In addition, recently, aluminum hydroxide (AL
When heated, (OH) ₃ ) decomposes into H ₂ O
Releases (water vapor).

2AL ((OH) ₃ ) → AL ₂ O ₃ + 3H
₂ O (steam) ◎ The flame-retardant effect of aluminum hydroxide is due to such endothermic action of water. The results of the material selection test measured as described above are described in Table 1 above. According to this, various materials are (a) of the type that reduces thermal conductivity due to a foaming phenomenon during heating, ) Those which show a remarkable effect on the endothermic properties during thermal decomposition, (c) The thermal decomposition product forms a carbonized layer and protects the internal insulator, and (d) The above (a), (b) and ( C) is roughly divided into those that have the effect. From these test results, the size of 3 × 14 mm ² .
Various materials selected in Table 1 are wound on a 6 kV CV cable in a thickness shown in Table 2, and a polyvinyl chloride-based jacket is extrusion-coated on the various materials to make various cables having the structure shown in FIG. Materials: 1-14) were prepared.

[0012]

[Table 2] Regarding these various cable samples, Fire Service Agency Notification No. 7
Table 2 shows the results of the fire resistance test conducted according to the method specified in No. In addition, in the case of 6.6kV cable,
Burning time was raised to 840 ° C in 30 minutes, during which 4.4
Withstand a 10-minute withstand voltage test at kV and then at 7.6 kV,
Moreover, the insulation resistance immediately before 30 minutes after the start of combustion is 1 megohm or more. Therefore, the pass / fail judgment shown in Table 2 was judged to be acceptable if all of the standards of the above three items were satisfied. Table 2 shows that the sheath of a general CV cable has two kinds of heat-resistant and heat-insulating layers wound around it, and a flame-retardant polyvinyl chloride jacket is applied to it. The fire resistance was found to be excellent.

In the high-voltage fire-resistant electric wire having such a structure, since the winding layer of the mica tape does not exist between the conductor and the cross-linked polyethylene insulating layer, there is little risk of water tree generation,
In addition, since a jacket made of flame-retardant polyvinyl chloride exists in the outermost layer, when a fire occurs, first, the flame-retardant polyvinyl chloride burns to form a carbonized layer, and the carbonized layer causes the jacket to It is possible to prevent the heat insulating refractory layer existing inside from directly contacting the flame. Furthermore, due to the heat insulating effect of the heat insulating fire resistant layer, the heat transfer to the inside of the cable is delayed, and the heat absorbing chemical reaction caused by the heat of the heat absorbing fire resistant layer existing inside the heat insulating fire resistant layer causes the heat to the cable body. It is possible to further delay the heat transfer. Also, since a jacket made of flame-retardant polyvinyl chloride exists outside the heat-insulating fire-resistant layer made of epoxy glass cloth or a wound layer of flame-retardant paper, when laying wires or inspecting cable lines during use, etc. In addition, since the heat-insulating fire-resistant layer is not damaged, and the heat-insulating fire-resistant layer can be formed by winding a small number of epoxy glass cloth or flame-retardant paper, an inexpensive high-voltage fire-resistant electric wire can be provided.

[0014]

As is apparent from the above, in the high-voltage fireproof electric wire of the present invention, there is no risk of water tree generation,
In addition, the heat insulating refractory layer inside the jacket can be prevented from directly contacting the flame, and the heat insulating effect of the heat insulating refractory layer can delay the heat transfer to the inside of the cable. Due to the presence of, the heat transfer to the cable body can be further delayed. In addition, there is no risk of damage to the heat-insulating refractory layer when laying electric wires or when inspecting cable lines during use, etc. providing a stable high pressure fire electric wire
You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conventional high-voltage fireproof wire.

FIG. 2 is a cross-sectional view of a conventional high-voltage fireproof wire.

FIG. 3 is a cross-sectional view of the high voltage fireproof wire of the present invention.

FIG. 4 is an explanatory diagram showing a test situation for comparing heat insulation characteristics of various materials.

FIG. 5 is an explanatory diagram showing a measurement example of (DTA) in differential thermal analysis.

FIG. 6 is an explanatory diagram showing the DTA measurement status.

[Explanation of symbols]

 10 ………… Cable body 11 ………… Endothermic fire resistant layer 12 ………… Insulating fire resistant layer 13 ………… Jacket

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-53-50485 (JP, A) Real-open Sho-56-124918 (JP, U) Actual-open Sho-56-124920 (JP, U) Actual-open Sho-58- 95515 (JP, U) Actual development Sho 58-52818 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A cross-linked polyethylene insulating layer is provided on the outside of the insulating layer.
A heat-absorbing fireproof layer made of a wound layer of a tape containing aluminum hydroxide and a foaming agent is provided on the sheath of the cable body having a sheath on the epoxy glass cloth or flame-retardant paper. A high-voltage fire-resistant electric wire, characterized in that a heat-insulating fire-resistant layer composed of a wound layer is provided, and a jacket made of flame-retardant polyvinyl chloride is further provided on the heat-insulating fire-resistant layer.