JPS59162709A - 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 formed by electrically insulating the insulating shielding layer 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 an insulating layer, a slit 8 is formed, 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 43 at the ends of the two cables to be connected
As shown in the figure, after sharpening each into a pencil shape and connecting the conductor fll fl)' with a compression sleeve etc., the internal semiconductive layer 2 is formed on top of it using semiconductive tape or semiconductive heat shrink tube. . Next, a rubber or plastic insulating tape, such as a self-adhesive insulating tape, is wound over the inner semiconducting layer 2 over the cape stage insulating layer 43, and is 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 winding layer for forming the reinforcing insulating layer 4 is heated and fused together. As a result, the electric field at the tip increases, and the formed connection becomes more likely to break from this tip.

(b) When forming the slits 8 in the semiconductive layer 5, it is difficult to form them coaxially on a concentric circle, and therefore disturbances in the electric field are likely to occur.

In view of these drawbacks, the slit 8 shown in FIG. 1 is not required, and the insulation reinforcing layer 4 covering the cable conductor connection part of the rubber or plastic insulated cable cable shown in FIG. Volume resistivity at 106~10
An insulating shielding layer 6 is provided via a high dielectric constant and high resistance layer 7 having a relative permittivity of 6 to 100 and a dielectric constant of 12Ω.
A high-permittivity, high-resistance type insulated connection part was proposed to separate the

Here, the basis for the numerical value of this high dielectric constant and high resistance layer is that when the volume resistivity is below 106Ω・I and the relative permittivity is above 100Ju, flash shorting occurs due to the impulse voltage that enters the cable line. If the specific volume resistivity is 1012 Ω・1 or more and the dielectric constant is 6 or less, when a voltage is applied to the main connection part, the electric field will be concentrated between the insulation shielding layer 6 and the high dielectric constant, high resistance layer 7 in FIG. This is because it will be destroyed.

Conventionally, there is a method of forming a high-resistance layer having the above resistance range on the circumference of the insulator by appropriately adjusting a carbon-containing layer to form such a high-permittivity, high-resistance edge cut. There was a problem in that the resistance value of the high-resistance layer containing only the above-mentioned materials tends 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 and simple insulated connection.

In other words, the high dielectric constant, high resistance layer (edge cut portion) 7 in FIG.
As for 100 parts by weight of base resin, 50 parts by weight of silicon carbide
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. Base resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and ethylene-α-olefin-polyene ternary copolymer! For example, Mitsui Petrochemical's elastomer (ethylene/l-butene 5-ethylidene-2
- norbornene terpolymer)), these materials alone or a blend of two or more thereof, or a crosslinked product thereof are suitable.

Next, to briefly explain the reason for the limited quantity in the present invention,
The blending amount of silicon carbide is 50 parts by weight based on 100 parts by weight of the base resin.
If the amount is less than part by weight, the electrical resistance will change depending on the thermal history, so it is not possible.

Moreover, if it exceeds 700 parts by weight, the composition becomes very hard.
It is difficult to process, so it is not possible. Further, if the carbon content is less than 2 parts by weight, the desired dielectric constant resistance cannot be obtained, so it is not acceptable.On the other hand, if it exceeds 60 parts by weight, the composition becomes hard and difficult to process, so it is not acceptable.

The effects and features of the structure of this invention are that, compared to a high dielectric constant and high resistance layer containing only carbon black, the inclusion of silicon carbide prevents carbon black from moving 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. In other words, (1) Wrap the tape with the above-mentioned composition on the connection portion reinforcing insulator layer 4. In some cases, after winding the tape, it is heat-fused to the connection portion reinforcing insulator layer 4.

(2) A tube made of the above compounded composition is prepared in advance according to the outer diameter of the designed connecting portion reinforcing insulating layer 4, and after molding the reinforcing insulating layer 4, the tube is made of the above-mentioned compounded composition. Insert the tube, cover it, and heat-seal it.

(3) After molding the reinforcing insulating layer, a mold is placed on the insulating layer, and the above compounded composition is injected 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 edge, but for example, for a 66KV class cable, the thickness is 1 to 3 tnm, and the separation distance between the insulation shielding layers is 50 to 100+ m. is preferred.

Example 1 A 600m++t154KV cross-linked polyethylene insulated cable with an insulation weight of 3 was sharpened with a pencil and then compressed into a compression sleeve (
After connecting conductor L II with semi-conductive tape (not shown),
A tape made of Nippon Unicar Co., Ltd. (trade name: DFD, JO580) was wound onto the conductor connection portion and then heat-formed at a temperature of 150° C. for 4 hours. Thereafter, a mold (not shown) was attached around the formed conductive layer 2, and a polyethylene composition containing a crosslinking agent (HFDJ4201
(trade name manufactured by Nippon Gounika Co., Ltd.)] was extruded into a mold. The set temperature of this extruder (not shown) is 120
It was ℃. 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. in,
The above semiconductive tape was wrapped around the edge cut distance 100 mm and other parts. The connection thus obtained is then connected to a vulcanized tube (
(not shown), heated at a temperature of 210"C for 6 hours in a nitrogen gas atmosphere of 8 kg/cr/I, and then cooled under gas pressure.The thickness of the joint reinforcing insulator layer 4 is After forming the connection part, the high dielectric constant and high resistance layer was subjected to alternating current volume resistivity and impulse flash breakdown voltage tests. Electricity was applied for 8 hours. After conducting the heat cycle test, the high dielectric constant and high resistance layer was subjected to alternating current volume resistivity and impulse flash breakdown voltage tests. 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 λ3 of a 250 mm 66 KV cross-linked polyethylene insulated cable, a compression sleeve (not shown) was applied.
After connecting the exposed conductors 1 and 12, a conductive tape (a tape of DFDJ, 0580 manufactured by Nippon Unicar Co., Ltd.) was wound over the conductor connection portion, and then heated to a temperature of 150°C.
It was heat-molded for 3 hours. Thereafter, a mold (not shown) was attached around the formed conductive layer 2, and a crosslinkable polyethylene composition (HFDJ 4 manufactured by Nippon Unicar Co., Ltd.
201) was extruded into a mold so that the insulation thickness was 12Ml11. The settings for this extruder (not shown) are 120
It was ℃. Next, after cooling, the mold was removed, and a tape of the composition shown in Table 2 below was applied to the high dielectric constant and high resistance layer shown in FIG. Now, the edge cutting distance was 70 mm, and the above semiconductive tape was wrapped around the point 6 in Fig. 2. Place this connection part into a vulcanizing tube (not shown) and use nitrogen gas of 8 kg/Cr! , ambient temperature 210°
C for 4 hours and cooled under gas pressure to form a connection part.

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 so that the conductor temperature was 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 pencil sharpening the insulator waste container 3 of a 250+u66KV ethylene-propylene rubber insulated cable, the conductor was exposed with a compression sleeve (not shown).

]'//After connection, apply semi-conductive tape (DFD manufactured by Nippon Unicar)
J 0580 (made into a tape) was wound onto the conductor connection □ portion, and then heated and molded at a temperature of 150° C. for 3 hours. Thereafter, an ethylene-propylene copolymer tape (a tape made of Nordel 2722 manufactured by Du Pont) was wound on the semiconductive layer 2 formed so that the insulation thickness was 20 mm, and then a third layer was wound on the insulator 4. In order to create the edge cut portion 7 shown in FIG. 2, a tape made from the composition shown in Table 2 1 was used to a thickness of 2, and the edge cut distance was 70III+11, and semiconductive tape was wrapped at the location shown in FIG. 2 6. Place this connection part into a vulcanization tube (not shown), add nitrogen gas to 8/9/cd, and atmosphere temperature to 21
A connection portion was prepared by heating at 0° C. for 4 hours and cooling under gas pressure.

After creating the connection, the volume specific resistivity of the cut edge part at AC is 2.
×10Ω·a1 impulse flash voltage was 140 KV.

After performing 200 heat cycles on this connection part at a conductor temperature of 90°C, energizing for 8 hours and stopping for 16 hours,
There was no change in the characteristics after the above test.

Example 4 After sharpening the insulator leakage 3 of a 600+n4154KV cross-linked polyethylene insulated cable, connect the exposed conductors 1 and 1' with a compression sleeve, and then apply semiconductive tape (a product manufactured by Furukawa Electric Co., Ltd.) on the conductor connection part. A conductive C tape) is wound around the semi-conductive layer 2, and an insulating tape based on ethylene propylene rubber (Fuko Fuco 3 manufactured by Furukawa Electric Co., Ltd.) is wrapped around the semi-conductive layer 2.
No. 1) was wound to an insulation thickness of 50 mm to form a connecting portion reinforcing insulator layer 4. 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.
The impulse flash voltage was 120 KV.

A heat cycle test was conducted in which electricity was applied to this connection 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 Insulator 3 of 66KV250-polyethylene insulated cable
, 3, connect the exposed conductors 1 and 1' with the compression sleeve, and then apply semiconductive tape (
c mixed with 100 parts of polyethylene (NUC9025) and 70 parts of carbon black (Vulcan XC72)
compound) was wound onto the conductor connection part and heated and molded at 120°C for 1 hour to form the semiconductive layer 2.
was formed. Next, insulating tape (polyethylene (NUC)
9025) into a tape) with an insulation thickness of 12 mrn.
Then, in order to create the edge cut portion 7 shown in FIG. 2, a tape made from composition 4 of Example 20 was wound to a thickness of 2 times. Next, connect this connection with nitrogen gas sky /
d. Heating was performed 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.
×jOΩ・I, impulse flash voltage is]] OKV
Met.

A heat cycle test similar to that in Example 1 was conducted for this connection, but there was no change in the characteristics of the edge cut portion.

[Brief explanation of the drawing]

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, II...Conductor, 2...Inner semiconducting layer, 3...Cable insulator layer, 4...Connection part reinforcing insulator layer, 5...Connection part outer semiconducting layer, 6...Connection part outer semiconducting layer . 7. High dielectric constant, high resistance layer, 8. Slit part (edge cutting 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 that covers the cable conductor connecting part, the insulating shielding layer is made of plastic as a base, and the amount of the insulating shielding layer is 100 parts by weight A rubber characterized by being provided in a state in which left and right sides are opposed in the longitudinal direction with a high dielectric constant and high resistance layer made of a mixture of 50 to 700 parts by weight of silicon carbide and 2 to 60 parts by weight of carbon black. , insulated connections for plastic insulated cables.