JPH03171513A - Solid type submarine power cable - Google Patents

Abstract

PURPOSE:To enable manufacture by means of an ordinary manufacturing technique and an ordinary manufacturing equipment while making an electric power line into a uniform radial shape from the center so as to eliminate an electric weak point and to thin the insulation thickness for making a cable outer diameter smaller by using a circular conductor and a circular insulating layer. CONSTITUTION:An insulating tape impregnated with high viscosity insulation oil is wound around a circular conductor 1 for forming an insulating layer 2 and a shielding layer 3 while the layer 3 is electrically connected to a lead coating 6. A spacer 4 is arranged in the outside opposing position for being fixed by a conductive tape 5 provided with the lead coating 6 thereon in order to make the lead coating 6, which is to be provided on the layer 3, elliptical. An outer spacer 9 is arranged outside the lead coating 6 to be provided with a plastic coated layer circular in shape thereon in order to form a steel wire armor 8 on its outside. Since in this way the circular conductor and the circular insulating layer are used, manufacture can be made by an ordinary technique and an ordinary equipment while eliminating an electrical weak point of the insulating layer and thinning the insulation thickness so as to make a cable outer diameter smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a solid submarine power cable that does not require oil supply from both ends of the cable.

(Prior art and problems to be solved) Solid power cables do not have oil tanks, so when a load is applied to the power cable, the temperature of the conductor and insulation layer rises, and the high viscosity solid insulation impregnated in the insulation layer The oil expands, and conversely, when the load is removed and the conductor and insulation layer become cold, the solid insulating oil contracts. Since the insulating oil has a high viscosity, the insulating oil expands and contracts repeatedly locally.

When such a solid type power cable is used as a submarine cable, for example in a shallow sea area of about 150 m or less, the expansion of the insulating oil causes the lead sheath to balance the pressing force of the reinforcing tape made of stainless steel or bronze provided on the outside. However, even if the insulating oil contracts after that, the external pressure due to seawater is small, so the lead coating will not contract, and even if external force is repeatedly applied to the internal insulating layer, the insulating layer will not be damaged. Also, it does not cause damage to the lead coating.

However, when the water depth exceeds 150 m, the external pressure due to seawater increases, and the lead sheath expands and contracts as the insulating oil expands and contracts due to load fluctuations, damaging the internal insulation layer and causing the lead sheath to become circular. Because of this, concentrated strain occurs due to expansion and contraction, resulting in damage due to repeated strain. In addition, in severe cases, vertical lead coating wrinkles may occur due to seawater pressure during contraction.
Thereafter, this problem does not disappear and becomes larger and larger, leading to damage to the lead coating or damage to the internal insulating core.

In order to avoid the above-mentioned phenomenon, in solid submarine power cables for deep sea use, measures have been taken in which the conductor is made into an oval shape, an insulating layer is wound on top of the conductor, and an oval lead sheath is applied. With this configuration, the ratio of the oval shape, that is, the ratio of the major axis to the minor axis (for example, 1.1
) within a certain range, the lead sheath keeps its outer circumference constant and smoothly changes from Nagata shape to circular shape to oblong shape repeatedly to absorb the expansion and contraction of the insulating oil, so there is no damage to the insulating layer. No concentrated strain occurs on the lead coating.

However, manufacturing an oval conductor and winding an insulating tape thereon to form an oval insulating layer requires very difficult technology and equipment, and productivity is significantly reduced. Electrically, as shown in Figure 2 (a), the electric lines of force (a) are concentrated at the part of the oval conductor where the ratio is the smallest, and this becomes the weak point. Therefore, it is necessary to increase the thickness of the insulating layer in order to obtain the necessary withstand voltage characteristics in this portion, which leads to an increase in the outer diameter of the cable. Even if I do that again,
This is still the electrical weak point.

(Means for Solving the Problems) The present invention provides a solid type submarine power cable that solves the above-mentioned problems, and is characterized by the winding of an insulating tape impregnated with high viscosity insulating oil on a circular conductor. A spacer is placed on the outer side of the cable core, which has an insulating layer and a shielding layer provided thereon, and a spacer is placed thereon to make the lead sheath into an oval shape. This is due to the fact that a layer and an outer layer of iron wire are provided.

(Function) In the solid submarine power cable of the present invention described above, a circular conductor is used, and an insulating layer and a shielding layer are provided on the conductor in a circular shape. Can be manufactured.

In addition, since the shielding layer, which is electrically on the ground side, is also circular, as shown in Figure 2 (b), the lines of electric force (a) in the cable are uniformly radial from the ideal center, and local No weaknesses arise.

(Example) FIG. 1 is a cross-sectional view of a specific example of the solid type submarine power cable of the present invention.

In the drawings, (l) is a circular conductor such as a compressed circular conductor used as a conductor for ordinary power cables, and (2) is, for example, kraft insulating paper, a composite insulating tape made by laminating kraft insulating paper and a plastic film such as polypropylene. , ethylene-propylene copolymer film, or a mixture of these, wound together and impregnated with high viscosity insulating oil, to form an insulating layer; (3) is a shielding material wound with carbon paper, metal tape, copper-woven cloth tape, etc. This shielding layer (3
) must be electrically connected to the lead coating (6) applied over it.

(4) is a spacer placed on the outer side of the lead coating (6) applied to the shielding layer (3) to form an oval shape. This spacer (4) is preferably made of a material that has almost the same mechanical properties as the material constituting JEI (2), and in that sense, it is best to form it with the same material as the material used for the insulating layer. This is preferable since there is no fear of a decrease in However, since the spacer is ultimately used to make the lead sheath into an oval shape, it may be made of, for example, a plastic extrusion, an insulating tape wrapped around the extrusion as a core, or lead or a lead alloy. It may also be a core with insulating tape wrapped around it. Such spacers (4) are arranged on opposite sides of the circular core, and a metal tape, a copper-woven cloth tape, or a semiconductive cloth tape, carbon paper, or a semiconductive cloth as a layer of these tapes and Kuhn B are placed on opposite sides of the circular core. Conductive tape (5
) and apply lead coating (6) to the -Jtii-4.

In this way, the conductive tape (5
), the shielding layer (3) on the circular insulating layer (2)
This is preferable because the spacer (4) and the lead coating (B) are electrically connected, and the spacer (4) and the lead covering (B) are also electrically connected.

Further, on the outside of the oval lead sheath (6), there is a
To make J2 (8) easier to handle, it is easier to handle the cable after sheathing, and to prevent damage to the cable during and after installation due to concentration of external force due to its oval shape. A plastic covering layer (7) made of polyethylene or the like having a circular outer shape is provided on the outside, and a steel wire sheathing (8) is provided on the outside thereof.

To provide such a circular plastic coating layer (7), an outer spacer (3) is placed in the lead sheath (6) at a position approximately perpendicular to the spacer (4), and a layer of polyethylene or the like is placed on top of the outer spacer (3). Alternatively, the outer spacer (9) may be omitted and an oblong lead sheath (6) may be extruded.
) The plastic ffl layer (7) may be formed by extruding a plastic material with uneven thickness so that it becomes circular after extrusion.

(Effects of the Invention) As explained above, according to the solid type submarine power cable of the present invention, the cable core uses a circular conductor and a circular insulating layer like a normal power cable, so normal manufacturing technology and manufacturing equipment can be used. This makes manufacturing possible and significantly improves productivity.

Furthermore, compared to an oval conductor and an oval insulating layer, there is no electrical weakness in the insulating layer, so the insulation thickness can be made thinner and the outer diameter of the cable can be made smaller.

Furthermore, by providing a circular-shaped plastic coating layer on the outside of the oval lead sheath and applying a steel wire exterior to the outside,
Exterior work is facilitated, and the cable is not damaged during or after installation due to concentration of external force due to its oval shape.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a specific example of the solid type submarine power cable of the present invention. FIG. 2 is an explanatory diagram of electric lines of force generated in the insulating layer, where (a) shows the case of a conventional cable, and the figure (opening) shows the case of the cable of the present invention. DESCRIPTION OF SYMBOLS 1... Circular conductor, 2... Circular insulating layer, 3... Shielding layer, 4... Spacer, 5... Conductive tape layer, 6...
...Lead coating, 7...Plastic coating layer, 8...Iron wire exterior, 9...Outer spacer.

Claims (3)

[Claims] (1) A circular conductor is coated with an insulating layer and a shielding layer by winding an insulating tape impregnated with high viscosity insulating oil, and the lead sheathing applied on the cable core is placed in an oval shape at opposing positions on the outside. A solid type submarine power cable characterized by having an oval lead sheath with spacers arranged thereon, and a plastic sheath and a steel wire sheath on the outside. (2) Wrap conductive tape around the outer circumference of the spacer, or
The solid type submarine power cable according to claim 1, characterized in that the spacer or/and the spacer are electrically conductive. (3) The solid type submarine power cable according to claim (1), wherein the outer shape of the plastic coating layer applied to the outside of the oblong lead sheath is circular.