JPS5847830B2 - Shrink tube for cable insulation connection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shrink tube suitable for insulating connection of high voltage cables.

Electric wires and cables that use cross-linked polyethylene for the insulation layer are
In recent years, it has been increasingly used as high voltage cables.

Along with this, reliability is also required in the connection parts of these electric wires and cables, and a mold type that applies a rubber/plastic reinforcing insulation layer on the conductor connection part and integrates it with the cable insulation layer by heating and pressurizing. Connections have become widely adopted.

On the other hand, there is a tendency for such cables to be applied to actual lines over longer distances, and it has become necessary to provide so-called edge portions of the insulating layer on the outer semiconductive layer for shielding.

Conventionally, the shape of the above-mentioned cable connection part (referred to as an insulating connection part) is to wrap a semiconductive material in a tape shape from the end to the center on the reinforcing insulating layer, and then wrap an insulating tape around the end of the tape to form an edge. The method used is to provide a cut portion and then wrap a tape made of semiconductive material on the other side, making the process of forming the cut portion complicated and time consuming.

The present invention eliminates the above-mentioned drawbacks of the conventional cable insulated connection part, and consists of one ends of two semiconductive shrink tubes that are overlapped with each other via an insulating part to form an edge cut part and integrated. The shrinkable tube is characterized in that its inner diameter is larger than the outer diameter of the reinforcing insulating layer of the cable connection section.

Since the above-mentioned shrinkable tube of the present invention has a cut edge in advance, a connection with a cut edge can be created by simply covering the reinforcing insulating layer with the shrink tube and heating and shrinking it, making it possible to greatly expand the joint construction method. It can be rationalized.

In addition, if the electron beam is aimed only at the part including the edge cutting part and this part is made to be less likely to shrink than both ends, the shrinkage force in this part will be smaller and the shrinkable tube will not sink into the reinforcing insulating layer. It has also been found that it is further advantageous as a shrink tube for cable insulation connections.

The present invention will be explained based on the drawings.

, FIG. 1 is a longitudinal sectional view showing the symmetrical upper half of the shrink tube of the present invention.

1 and 2 are the semiconductive parts of the shrink tube, 3 is the edge cutting part, and 4
, 5 are the edge portions of the semiconductive portions.

Since the present invention is a shrinkable tube having the above structure, it is manufactured as follows.

A semiconductive shrink tube is attached to an aluminum pipe 6 whose inner diameter is smaller than the outer diameter of the reinforcing insulating layer.
The semi-conductive portion 1 is formed by placing the semi-conductive portion 1 on top and shrinking it by heating with a burner, torch lamp or the like.

At this time, heat shrinkage is performed from the opposite side of the edge 4, and before the semiconductive shrink tube is completely shrunk, the edge 4 of the semiconductive shrink tube is bent. Add a gentle radius to the side end 4.

Next, the stretched polyethylene tape is wound to form the edge section 3, and a portion of the edge section 3 and the aluminum pipe 6 are covered with another semiconductive shrink tube and heated and shrunk to form the semiconductive section 2.

At this time as well, the edge portion 5 of the semiconductive portion 2 bends the tip of the tube to create a gentle radius.

Thereafter, the aluminum pipe 6 is removed, and the manufacture of the shrink tube for cable insulation connection of the present invention is completed.

FIG. 2 is a longitudinal sectional view showing a symmetrical upper half of a cable insulated connection formed by applying the shrink tube of the present invention.

In FIG. 2, 7 is a conductor, 8 is a conductor connection part, and 9 is a cable insulation part.

10 is a reinforcing insulating layer, and 11 is a shrink tube of the present invention.

Next, the method for manufacturing the shrinkable tube of the present invention will be specifically described.

A tube with an inner diameter of 25mm and a thickness of 27mm and 7mm was made using semiconductive polyethylene containing carbon black.
After being irradiated with a Mrad electron beam, it was expanded to an inner diameter of 70 mm.

Cut this tube to a length of 30cIrL, and cut one end to a length of 5cIrL.
IrL was bent, placed on an aluminum pipe cut in half in the longitudinal direction and having an outer diameter of 6Q+++mφ, and heated and shrunk with a torch lamp.

A lengthwise stretched cross-linked polyethylene tape was then wrapped over the bent end of the tube and over the aluminum pipe to a thickness of approximately 3 mm.

Furthermore, another semiconductive shrink tube, one end of which was bent in the same manner, was placed over a portion of the cross-linked polyethylene tape and the aluminum pipe, and the tube was heat-shrinked.

Next, the whole was heated at 150° C. for 30 minutes to integrate it, and then the aluminum pipe was removed to complete the shrink tube of the present invention.

Further, it is preferable that the shrink tube is irradiated with an electron beam of 20 Mrad only on the portion including the edge cut portion.

The reason for this is that unless the above-mentioned part of the shrink tube is illuminated with an electron beam, when the entire cable connection section is heated and pressurized, the shrinkage force at the cut edge will be greater than in other parts, so the cut edge will be reinforced and insulated. This is because the phenomenon of being pushed into the layer is observed, but when compared with electron beams, the shrinkage rate of that part becomes small, and the above phenomenon disappears even if the entire connection part is heated and pressurized.

When applying the shrink tube to cable insulation connections, it is done as follows.

Conductor cross-sectional area 1. Using a 5 om4 cross-linked polyethylene cable, conductor connections are made and a 107n7 thick
n reinforcing insulating layers were provided, and then the aforementioned shrinkable tube with edge cut portions was placed thereon and heat-shrinked to complete the insulated connection of the cable.

Compared to the conventional joint construction method, in which the edges were made by wrapping tape, the time required for connection was significantly reduced.

Furthermore, the resulting cable connection had good electrical performance and sufficient reliability as an insulated connection for high-voltage cables.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing the symmetrical upper half of the shrink tube for cable insulation connection of the present invention, and Fig. 2 shows the symmetrical upper half of the cable insulation connection part formed by applying the shrink tube of the present invention. FIG. 1, 2...Semi-conductive part, 3...Edge section, 4, 5... Edge section side end of semi-conductive part,
10...Reinforcement insulation layer, 11...Shrink tube.

Claims (1)

[Scope of Claims] 1. A shrinkable tube in which one ends of two semiconductive shrinkable tubes are overlapped with each other via an insulating part to form an edge section and are integrated. A shrinkable tube for connecting cable insulation, characterized in that the inner diameter is larger than the outer diameter of the reinforcing insulation layer of the cable connection part. 2. The shrinkable tube for cable insulation connection according to claim 1, wherein the shrinkage rate of the portion including the edge cut portion is smaller than the shrinkage rate of other portions.