JPS5832214Y2 - Connection part of cross-linked polyethylene insulated cable - Google Patents

Description

[Detailed description of the invention] This invention is a cross-linked polyethylene insulated cable (hereinafter referred to as CV
Abbreviated as cable.

) regarding the structure of the connection part.

Conventionally, in order to form a connection part of a high voltage CV cable of 22 KV class or higher, an insulation reinforcing part has been provided on a cable conductor connection part connected through a sleeve by the following method.

Namely. ■) A method of winding a polyethylene tape that has been crosslinked in advance by electron beam irradiation, etc., winding a restraining tape on top of it, and then heating it from the outside to fuse the polyethylene tape wound layer and forming it. ■) A method of applying a crosslinking agent A method has been adopted in which a mixed uncrosslinked polyethylene tape is wound, the tape is crosslinked by heating, and at the same time the wound layers are fused and integrated.

However, among these methods, method I) has the advantage that the heating time can be somewhat shortened because the tape is already crosslinked, and deflection is less likely to occur, but on the other hand, the tape has poor thermal adhesive properties. Therefore, there has been a drawback that areas where pressure is not easily applied by the tape, such as the interface with the stripped cable insulation, are likely to peel off, and voids are likely to occur.

In addition, in method (■), since fusion bonding and crosslinking are performed at the same time, the winding part is completely integrated and electrical properties equivalent to those of cable insulation can be expected, but on the other hand, it is difficult to set the conditions for heating. The drawback was that strict working conditions were required.

Furthermore, in either method, the polyethylene tape expands in the length direction by several diameters when heated, which sometimes causes the tape winding layer to fold in the radial direction of the cable, which can lead to deflection. There was a problem.

The present invention was devised to solve these conventional difficulties, and consists of an insulation reinforcement section by winding a heat-shrinkable cross-linked polyethylene tape having a shrinkage rate and degree of cross-linking within a certain range. This provides a connection part for high-voltage C■ cables.

The heat-shrinkable cross-linked polyethylene tape used in this invention is made by stretching polyethylene that has been cross-linked by electron beam irradiation or chemical cross-linking, and has the property of shrinking to its original state when heated above its melting point. It has a crosslinking degree of 10% to 80% and a heat shrinkage rate of 2 to 67.
A range of 50% to 7% is appropriate, more preferably 50 to 7%.
It is preferable to use one with a degree of crosslinking of 0% and a shrinkage rate of 5 to 10%.

The reason why the degree of crosslinking is limited to the above range is that if it is less than 10, the heat resistance and heat deformation resistance of the insulation reinforcement part after molding will be poor, and if it is more than 80%, the heat fusion properties during heating will be poor. This is because it is insufficient and cannot be put to practical use in either case.

Furthermore, the reason why the value of the heat shrinkage rate is limited as above is that when a tape with a shrinkage rate of less than 2% is heated, the tape itself tends to return to its pre-stretching thickness at the same time as the heat shrinks, and as a result, the tape itself tends to shrink in the radial direction. Due to thermal expansion, this thermal expansion cannot be compensated for by contraction, which is undesirable. Also, in the case of tape with a diameter of 67φ or more, a large strain remains after heat fusion, and the electrical characteristics of the connection part are affected. This is because there is a problem that the temperature decreases.

Hereinafter, the present invention will be explained based on the embodiments shown in the drawings.

As shown in the figure, the connection part of the high voltage CV cable of the present invention consists of a pair of cable conductors 1 whose ends are exposed by stripping the steps,
1 through a conductor sleeve 2, a wound layer 4 of heat-shrinkable cross-linked polyethylene tape provided thereon over the cable insulators 3 and 3'; It is mainly composed of a semiconductive layer 5 and an anticorrosive layer 6 which are further provided.

倚、7、7 company's pair of cable semiconducting layers, 8.8' shows a pair of cable sheaths.

The wound layer of the heat-shrinkable cross-linked polyethylene tape of the present invention is
After wrapping a tape with high mechanical strength on top of it, the layers are fused and integrated by heating, but in that case, the tape heated above its melting point immediately begins to shrink.
Since pressure is generated in the direction of winding the tape, the folding phenomenon often seen in the past does not occur.

In addition, as the tape shrinks in the length direction, the tape tries to return to its pre-stretching thickness and the entire one-turn layer tries to expand in the radial direction. further perfect the heat fusion.

As is clear from the above description, the connection part of the present invention has excellent electrical and mechanical properties, and can be configured not only for ordinary straight connection parts but also for Y-branch connection parts and terminal parts. be able to.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of a cross-linked polyethylene insulated cable according to the present invention. 1.1'...Cable conductor, 2...Conductor sleeve,
4... Wound layer of heat-shrinkable cross-linked polyethylene tape.

Claims (1)

[Scope of utility model registration request] On the conductor connection part, the degree of crosslinking is 10-80% and the shrinkage rate is 2.
~67% heat-shrinkable cross-linked polyethylene tape and a tape with high mechanical strength are wound in layers, and the winding of the heat-shrinkable cross-linked polyethylene tape is present between the conductor connection portion and the winding layer of the high-mechanical strength tape. A connecting portion of a cross-linked polyethylene insulated cable, characterized in that the interlayers are heat-fused and integrated at a heating temperature higher than the melting point of the tape.