JPS60165008A - Method of producing plastic insulated power cable with watershielding layer - 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 (Technical Field of the Invention) The present invention relates to polyethylene, crosslinked polyethylene, ethylene-
The present invention relates to an improvement in the method of manufacturing a plastic insulated cable that is coated with a plastic insulator such as a propylene copolymer by extrusion and has a water-repellent layer on the outside.

(Background of the invention) Extrusion coating of a plastic insulator such as polyethylene, crosslinked polyethylene, ethylene-propylene copolymer, etc.
Plastic insulated cables with an external plastic sheath made of polyethylene, vinyl chloride resin, etc. are made of insulators and semi-conducting materials, due to the presence of moisture inside the cable over many years of use and moisture entering the cable from the outside. Water trees may occur between layers or in the insulation, reducing insulation performance.

Cables with a water barrier layer on the cable core have been adopted to prevent moisture from entering from the outside, but the current situation is that the effects of moisture existing within the cable still remain.

Figure 2 is a cross-sectional view illustrating the outline of a plastic insulated power cable with a water barrier layer, (II) is the stranded conductor of the cable, (12) is the internal semiconducting layer, and usually the plastic insulating layer (13). extruded at the same time. (13) is an insulating layer coated with extrusion of plastic such as polyethylene, crosslinked polyethylene, ethylene-propylene copolymer, etc.
) is copper tape, a metal shielding layer composed of copper wire wound, (IG) is an external semiconducting cloth tape layer, (IG) is an indicator tape layer printed with the manufacturer's name, year of manufacture, etc., (17) is aluminum , a water barrier layer made of metal materials such as lead and stainless steel, or lead laminate, etc., (18) is polyethylene,
This is an anti-corrosion layer made of plastic material such as vinyl chloride resin.

Although the cable provided with the water-repellent layer (17) can prevent moisture from entering from the outside during use, moisture that has entered the cable conductor, insulator, and tape during cable manufacturing still exists. There is a possibility that this may cause water trees to occur. In particular, tapes absorb moisture in a short period of time, and after drying, if left in the air for about 10 hours, the moisture content will be the same as before drying), even if stored in a dry state, during tape winding work and after tape winding There was a problem in that moisture was absorbed during the process of later applying a water barrier layer, making it impossible to obtain the drying effect beforehand. Another method is to store the cable core wrapped with these tapes in a vacuum container before applying the water barrier layer, and then evacuate it to remove the tape and other moisture contained in the cable core. However, in this case, there is a new problem that requires a vacuum container that can house the drum in which the cable core is wound.

(Disclosure of the Invention) The present invention provides a method for manufacturing a plastic insulated cable having an improved water barrier layer that solves the problem described in 1. From one end of the plastic insulated power cable, low-pressure gas is supplied between the cable core and the water barrier layer, and at the other end of the power cable, a vacuum device is used to vacuum between the cable core and the water barrier layer. This method is characterized by removing moisture from the tape applied to the cable core by evacuation and releasing the gas.

FIG. 1 is a diagrammatic explanatory view of the manufacturing method of the present invention, with the cable end portion enlarged for ease of understanding. In the figure, (1) is a plastic insulated cable with a water layer wound around the cable drum (2), and (3) is an insulated cable made of polyethylene, cross-linked polyethylene, ethylene-propylene copolymer, etc. A cable core (4) with a metal shielding layer (+4L external semiconductive tape layer (IG) and a tape layer (16) such as a marking tape) on a plastic insulation layer (I3) with an extrusion coating
The cable core (3) is made by forming a metal laminate, which is made by laminating a plastic film such as polyethylene or ethylene copolymer on both or one side of a metal tape such as lead tape or aluminum tape, onto the cable core (3) vertically and forming it into a circular shape. Next to the water layer, a plastic layer made of polyethylene, vinyl chloride resin, etc. is provided.

A low-pressure gas supply device (6) is installed on the one end (172-) side of the cable (+), and a low-pressure drying device is installed between the cable core (3) and the water layer (4) through the gas supply pipe (5). A gas (7) such as air, nitrogen scum or SF5 is supplied.

On the other hand, a vacuum evacuation device (9) connected to a vacuum evacuation pipe (8) is installed on the other end (1 side) of the cable (1) to discharge the cape gas (7) to the outside.

At this time, the higher the pressure of the supplied gas, the greater the amount of gas passing through, which is more efficient, but since the metal laminate tape is soft and weak, when the pressure increases, it deforms outward and the outer diameter of the cable expands. The pressure of the gas is kept low enough not to expand the outer diameter of the cable, and by drawing a vacuum from the other end, the amount of gas passing through is increased, so that the purpose can be achieved efficiently in a short time.

(Effect of the invention) The electric power cable obtained by the manufacturing method of the present invention described above is as follows:
Moisture contained in cable core tapes is removed by binding the cable core or by supplying gas between the water layer and passing it through, so the moisture present in the cable is significantly reduced and the water layer is removed. Because of its long life, there is no intrusion of moisture from the outside even during long-term use, and it provides stable electrical performance.

Furthermore, a metal laminate tape was added as a water barrier layer.
Since it is small, it is not possible to increase the pressure of the body, but by evacuating from the other end, the amount of gas passing through can be increased and the objective can be achieved efficiently in a short time. It also has

[Brief explanation of drawings]

FIG. 1 is a diagrammatic illustration of the manufacturing method of the present invention, and FIG. 2 is a cross-sectional view illustrating the outline of a plastic insulated power cable having a water-repellent layer. DESCRIPTION OF SYMBOLS 1... Plastic insulated cable having a water barrier layer, 2... Cable drum, 3... Cable core,
4... Water barrier layer, 5... Gas supply pipe, 6...
Gas supply device, 7...low pressure gas, 8... vacuum evacuation pipe, 9... vacuum evacuation device. Agent Patent Attorney Hideji Aoki 2

Claims (1)

[Claims] A low-pressure gas is supplied from one end of a plastic insulated cable with a water barrier layer made of metal laminate tape on the cable core between the cable core binding and the water layer,
A method for manufacturing a plastic insulated power cable having a water barrier layer, the method comprising removing moisture from a tape applied to the cable core at the other end of the power cable.