JPS59162708A - Insulated connector of rubber and plastic insulated power cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to an insulated connection of a rubber or plastic insulated cable with a novel edge cut structure.

In long single-core cables, a potential is induced in the sheath by electromagnetic induction of conductor current, but this potential can be reduced by using the so-called cross-bond method. In such a cross-bond system, an insulated connection part is used as a cable intermediate connection part. The insulating connection portion is an insulating shielding layer electrically insulated using some means.

Conventionally, the edge cutting structure of the insulated connection part of this type of rubber or plastic insulated cable is as shown in FIG. It is known that a connecting portion insulating shielding layer 5 is coaxially provided on a reinforcing insulating layer to form a slit 8, and the insulating shielding layer is edged in the vertical direction. The insulated connection part of such a crosslinked polyethylene insulated cable is manufactured as follows.

First, the insulator layer 3 at the ends of the two cables to be connected,
3 into a pencil shape as shown in the figure, connect the exposed conductor (+) (1)' with a compression sleeve, etc., and then connect it with semiconductive tape or semiconductive heat shrink tube. An internal semiconducting layer 2 is formed. Next, a rubber or plastic insulating tape such as a self-adhesive insulating tape is wound over the inner semiconducting layer 2 over the cable insulating layers 3, 3, and then heated under pressure to be fused together. Alternatively, a desired mold (not shown) is provided around the internal semiconducting layer 2, molten resin is injected into the mold, and the connecting portion reinforcing insulating layer 4 is formed by heat-sealing it by an appropriate means. Form. Further, an external semiconducting layer 5 having a slit portion 8 coaxially provided on the outer periphery of the connecting portion reinforcing insulating layer 4 is provided to complete the connecting portion.

However, the insulated connections of such conventional rubber and plastic insulated cables have many drawbacks. That is, (a) the tip of the semiconductive layer 5 forming the slit 8 is deformed when the tape-wound layer for forming the reinforcing insulating layer 4 is heated and fused together; Since the electric field becomes larger, the formed connection becomes more likely to break from this tip.

(b) When creating slits in the semiconducting layer 5, it is difficult to make them coaxially on a concentric circle, which tends to cause disturbances in the electric field.

In view of these drawbacks, an AC insulator is added on the outer periphery of the insulating reinforcing layer 4 covering the cable conductor connection part of the rubber or plastic insulated cable cable shown in Fig. 2, which does not require the slit 8 as shown in Fig. 1. Specific volume resistivity] 0'~10
An insulating shielding layer 6 is provided via a high dielectric constant and high resistance layer 7 having a dielectric constant of 12Ω·α and a relative permittivity of 6 to 100.
A high-permittivity, high-resistance type insulated connection that cuts the edges in the longitudinal direction has been proposed. Here, the basis for the numerical value of this high dielectric constant, high resistance layer forming material is that the volume resistivity is 10Ω・σ or less, and the relative permittivity is 10
If it is above 0, the impulse voltage entering the cable line will cause a flash short circuit.1. On the other hand, volume resistivity 10 Ω・σ
As mentioned above, when the relative dielectric constant is 6 or less, when applying electricity to the main contact part, the second
This is because the electric field concentrates between the insulating shielding layer 6 and the high dielectric constant, high resistance layer 7, which easily breaks down.

Conventionally, there is a method of forming a high-resistance layer having the above-mentioned resistance range on the circumference of the insulator by appropriately adjusting the carbon content to form such a high-permittivity, high-resistance type edge cut. There were five problems in that the resistance value of the high resistance layer containing only carbon was likely to fluctuate due to thermal history such as heat cycling.

The object of the present invention is to eliminate the above-mentioned drawbacks of high dielectric constant, high resistance type insulated connections, and provide a stable, simple, and high performance insulated connection.

In other words, the high dielectric constant, high resistance layer (edge cut portion) 7 in FIG.
This insulated connection part is characterized by using a composition in which ~700 parts by weight and 2 to 60 parts by weight of carbon are mixed and blended. Among the base resins, rubber-based materials include ethylene propylene rubber, ethylene-vinyl acetate rubber, acrylic rubber, fluororubber, styrene-butadiene rubber, butadiene rubber, and plastic materials include low-density polyethylene, medium-density polyethylene 1/7, and high-density polyethylene. Density I) Ethylene,
Ethylene propylene rubber monomer J"4 polymer (E, P'DM), ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-α olefin-polyene terpolymer (e.g. Mitsui Petrochemical elastomer) (Ethylene 1-
Suitable materials include 2-norbornene ternary copolymers, single or blends of two or more of these materials, and vulcanized or crosslinked products thereof.

Next, to briefly explain the reason for the limited quantity in the present invention,
The amount of zinc oxide blended is 5 parts by weight based on 100 parts by weight of the base resin.
If it is less than 0 parts by weight, the electrical resistance will change depending on the thermal history, so it is not acceptable.

Moreover, if it exceeds 700 parts by weight, the composition becomes very hard.
In addition, if the carbon content is less than 2 parts by weight, the desired dielectric constant resistance cannot be obtained, and if it exceeds 60 parts by weight, the composition becomes hard. ,
It cannot be processed (because it is difficult to process).

The effects and features of the structure of this invention are that, compared to a high dielectric constant, high resistance layer containing only a power pump rack, the inclusion of zinc oxide makes it difficult for carbon black to migrate even when subjected to thermal history. , it is characterized by almost no change in resistivity.

The method for forming the edge cut portion is as follows. (1) The tape with the above-mentioned composition is wound onto the connection portion reinforcing insulator layer 4. In some cases, after winding the tape, it is heat-fused to the connecting portion reinforcing insulating layer 4.

(2) A tube made of the above-mentioned compounded composition is prepared in advance according to the outer diameter of the designed connecting portion reinforcing insulating layer 4,
After forming the reinforcing insulating layer 4, the tube is inserted and coated onto the reinforcing insulating layer 4, and heat-fused.

(3) After molding the reinforcing insulating layer, place a mold on this insulating layer,
The above compounded composition is injection molded or extruded according to the design of the edge cut portion. Furthermore, it is heat-fused to the insulating layer.

Here, the thickness and length of the high dielectric constant and high resistance layer vary depending on the rated voltage class, but for example, for a 66 KV class cable, the thickness is 1 to 3 mm, and the separation distance between the insulation shielding layers is 50 to 3 mm. 100+nm is preferred. Next, examples of the present invention will be shown.

Example 1 After sharpening the insulator 'a3 of the 6007++, a154KV cross-linked polyethylene insulated capeple, and connecting the exposed conductors 1 and 1t with a compression sleeve (not shown),
Semi-conductive tape (product name DFD manufactured by Nippon Unicar Co., Ltd.)
J 0580 (made into a tape) was wound onto the conductor connection portion and then heat-molded at a temperature of 150° C. for 4 hours. Thereafter, a mold (not shown) was attached to the period of the formed first conductive layer 2, and a polyethylene composition containing a crosslinking agent (HFDJ 42
01 (trade name manufactured by Nippon Unicar Co., Ltd.)] was extruded into a mold. The set temperature of this extruder (not shown) is 1
The temperature was 20°C.

Next, after cooling, the mold was removed, and a tape having a composition shown in Table 1 below was applied to the high dielectric constant and high resistance layer shown in FIG. 2 of the formed connection reinforcement insulating layer 4. Then, the above-mentioned semiconductive tape was wrapped around the edges at a distance of 100 mm and other parts.

The thus obtained joint was placed in a vulcanization tube (not shown), heated for 6 hours using a nitrogen gaff, and then cooled under gas pressure.

The thickness of the joint reinforcing insulator layer 4 was 25 mm.

After forming the connection part, the high dielectric constant and high resistance layer was tested for volume resistivity and impulse flash breakdown voltage under alternating current, and then electricity was applied for 8 hours every day for 200 days to bring the conductor temperature to 90°C. After conducting heat cycle tests, we conducted volume resistivity and impulse flash breakdown voltage tests of the high dielectric constant and high resistance layers under alternating current. The obtained results are also listed in Table 1.

As is clear from Table 1, the characteristics of the edge cut portions after heat cycle thermal history are much more stable than those of the comparative examples in all of the insulated connection parts according to the present example, compared to the conventional ones.

Example 2 After sharpening the insulator a3 of the 250 *wi' 66 KV cross-linked polyethylene insulated cable with a pencil, compressed it 1)'-
After connecting the exposed conductors 1 and 11 with a tape (not shown), semiconductive tape (DFDJ 05 manufactured by Nippon Unicar Co., Ltd.)
80 into a tape) was wound onto the conductor connection portion and then thermoformed at a temperature of 150° C. for 3 hours. Thereafter, a mold (not shown) is attached around the formed conductive layer 2, and a crosslinkable polyethylene composition (HFDJ4201 manufactured by Nippon Unicar) is injected into the mold using an extruder so that the insulation thickness is 12 mm. Extruded. The extruder (not shown) was set at 120°C. Next, after cooling, remove the mold,
The high dielectric constant and high resistance layer shown in FIG. 2 of the formed connection reinforcing insulator layer 4 was coated with two tapes having the composition shown in Table 2 below.
The thickness was 11 m1, the edge cutting distance was 70 mm, and the above-mentioned semiconductive tape was wrapped around the point 6 in FIG. The connected portion was placed in a vulcanized tube (not shown), heated for 4 hours at an ambient temperature of 210° C. under nitrogen gas of 8 kg/c+d, and cooled under gas pressure to form the connected portion.

After testing the high dielectric constant and high resistance layer of the connection portion molding for volume specific resistivity and impulse flash withstand voltage, electricity was applied for 8 hours every day for 200 days to maintain the conductor temperature at 90°C. After conducting heat cycle tests, we conducted volume resistivity and impulse flash breakdown voltage tests of the high dielectric constant and high resistance layers under alternating current. The obtained results are also listed in Table 2.

As is clear from Table 2, it can be seen that the characteristics of the edge cut parts after heat cycle thermal history are much more stable than those of the comparative example in all of the insulated joints according to this example, compared to the conventional ones. .

Example 3 After sharpening 3 on the insulator of a 250 gJ 66 KV ethylene-propylene rubber insulated cable, and connecting the exposed conductor 1°1' with a compression sleeve (not shown),
Semi-conductive tape (DFDJ 0580 manufactured by Nippon Unicar)
After winding the tape over the conductor connection portion, it was heat-molded at a temperature of 150° C. for 3 hours. After that, an ethylene-propylene copolymer tape (du
Tape made from Pont's Nordel 2722)
are wound so that the insulation thickness is 20, and then the insulator 4 is wound.
In order to create the edge cut portion 7 shown in FIG. 2 above, use a tape made of the composition 1 in Table 2 to a thickness of 2 cm, the edge cut distance is 70 mm, and a semi-conducting conductor is applied to the portion shown in FIG. 2 6. I wrapped the tape around it. Place this connection part into a vulcanization tube (not shown) and apply 8 kg of nitrogen gas.
/crI, heated at an ambient temperature of 210° C. for 4 hours, and cooled under gas pressure to create a connection part.

After creating the connection, the volume specific resistivity of the cut edge part at AC is 2.
×10 Ω·mouth, impulse flash voltage was 140 KV.

The above test was conducted after this connection was subjected to 200 heat cycles at a conductor temperature of 90° C., energized for 8 hours, and stopped for 16 hours, but there was no change in the characteristics.

Example 4 600m11154 ■Cross-linked po+)-r-f and 7 insulation'
After sharpening the r-pull insulator A3, connect the exposed conductor 1.1' with the compression sleeve, and then apply semiconductive tape (product name: Conductive C Tape, manufactured by Furukawa Electric Co., Ltd.) on the conductor connection. , further winding an insulating tape based on ethylene propylene rubber (Fuko Fuco No. 31, manufactured by Furukawa Electric Co., Ltd.) on this semiconductive layer 2 until the insulation thickness becomes 50 iam,
A connection portion reinforcing insulator layer 4 was formed. A tape of the same composition as 1 in Table 1 is applied to the edge cutting portion 7 shown in FIG. I made insulated connections by wrapping each piece of tape.

After creating the connection, the volume specific resistivity of the cut edge part at AC is 2.
x]09Ω·m, and the impulse flash voltage was j20KV.

A heat cycle test was conducted in which electricity was applied for 8 hours every day for 200 days so that the conductor temperature reached 90° C., but the characteristics of the edge cut portion did not change.

Example 5 After sharpening the insulator λ3 of a 66KV250- polyethylene insulated cable, connect the exposed conductors 1 and 1t with a compression sleeve, and then apply semiconducting tape (
com mixed with 100 parts of polyethylene (NUp9025) and 70 parts of carbon black (VulcanXC72)
A tape formed from Pound) was wound onto the conductor connection portion and heat-molded at a temperature of 120° C. for 1 hour to form a semiconductive layer 2.

Next, an insulating tape (polyethylene (NUC9025) made into a tape) was wound so that the insulation thickness was 12+U, and further, in order to create the edge cut portion 7 shown in FIG. It was rolled to a thickness of 2 dragons. Next, this connection portion was heated in nitrogen gas 8/day/I at an ambient temperature of 130° C. for 2 hours to form an insulated connection portion.

After creating the connection, the volume specific resistivity of the cut edge part at AC is 2.
×10Ω・I, the impulse flash voltage was 110 KV.

A heat cycle test similar to that in Example] was conducted on this connection, but there was no change in the characteristics of the edge cut portion.

[Brief explanation of drawings]

FIG. 1 is a schematic partial vertical cross-sectional view showing an example of a conventional insulated connection part of a rubber or plastic insulated cable, and FIG. 2 is a schematic partial vertical cross-sectional view showing an embodiment of the insulated connection part of the present invention. 1.1'...Conductor, 2...Inner semiconducting layer, 3...Cable insulator layer, 4...Connection part reinforcing insulator layer, 5...Connection part outer semiconducting layer, 6... Connecting portion external semiconducting layer, 7.
...High dielectric constant, high resistance layer, 8...Slit part.

Claims (1)

[Claims] 1. In the connection part of a rubber or plastic insulated cable cable in which an insulating shielding layer is provided on the outer periphery of an insulating reinforcing layer covering the cable conductor connection part, the insulating shielding layer is made of rubber or plastic as a base, and 100 parts by weight of the insulating shielding layer is A high dielectric constant, high resistance layer made of a mixture of 50 to 700 parts by weight of zinc oxide and 2 to 60 parts by weight of carbon black is disposed between the left and right sides in the longitudinal direction. Insulated connections for rubber and plastic insulated cables.