JPH047045B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ultra-high voltage OF cable, and particularly to a method for manufacturing an ultra-high voltage OF cable in which different types of insulating materials are mixed together layer by layer.

[Conventional technology]

In recent years, in order to reduce the dielectric loss (tan δ) of ultra-high voltage OF cables (275 to 500 kV) and increase the power transmission capacity, we have also improved the dielectric strength and made it more compact.
In order to make OF cables, low-loss insulation materials using various plastic materials have been developed and put into practical use. In order to make cables that take advantage of the characteristics of these materials, different types of insulating materials have come to be used together to create a single cable.

Let's take a look at a 500kV OF cable that uses PPLP for the inner insulation layer and PML for the outer layer.As an example, when the thickness of the total insulation layer is 25mm, the outer layer made of PML is It is said to be about 4 to 6 mm. PML is a composite insulating material made by laminating kraft paper on one or both sides of a polymethylpentene plastic film, which is a type of polyolefin plastic material, and is said to have excellent heat resistance. Used as an outer layer.

PPLP is a composite insulation material made by laminating kraft paper on one or both sides of a polypropylene plastic film, which is a type of polyolefin plastic material. Although this material has excellent electrical properties and economic efficiency, it tends to be weak against lead work.

Normally, in the process of wrapping insulating materials of different types, thicknesses, and widths around a conductor,
In order to avoid confusion, and because the paper winding tension of the paper rolling machine and the winding angle of the insulating tape on the paper roll are different, it is common practice to change the head of the paper winding machine for each insulating material tape, and to change the winding direction between the front and rear paper winding heads. It is.

[Problem to be solved by the invention]

By the way, according to this method, first 154kV
Equivalent to 1×1200mm ² , outer layer 3mm PML insulation layer (1
(approximately 170μ), inner layer of 9mm PPLP insulation layer (approximately 1 sheet)
170μ) with a total insulation thickness of 12mm.
When PPLP was manufactured by changing the paper winding head, a large gap occurred between the PML and PPLP layers, and due to bending, the PML layer was largely displaced from the PPLP layer, causing damage to the tape. Also, the first PML across this gap was loose, with approximately 3 to 5 cm of slack per meter of cable.

This especially occurs because the properties of PML and PPLP (elongation, tensile strength, hardness, degree of shrinkage due to drying, degree of swelling due to impregnation) are significantly different, and because the paper winding heads are different, the differences are even more emphasized. This is due to a complete interlayer gap.

Moreover, if paper is rolled in the same direction within the same paper-rolling head, it can be held down with the same tape one after another, so even if there is a gap, it will not move easily due to bending, and it will not cause much damage, but interlayer gaps between different heads will not allow the layers to be integrated. Because they grow and move easily, they cause even more damage.

This phenomenon occurs not only in PPLPML, but also in
This can occur to a greater or lesser extent with cables that use a mixture of insulating materials with significantly different properties, such as PPLPFEP and PPLP kraft paper, for each layer.

The FEP is a composite insulating material made by laminating kraft paper on one or both sides of a fluorinated ethylene propylene plastic film.

In addition, conventionally, when winding PPLP tape, for example, PPLP that has been pre-humidified is used to prevent swelling during actual use (see Japanese Patent Publication No. 52-38287). PPLP tape loses weight and becomes rough due to drying, and is then impregnated with insulating oil at room temperature before being cut and shipped. After installation, the PPLP tape is exposed to high temperatures for the first time in actual use, and swells sufficiently to form the optimal hardness as an insulating layer. Because it becomes Satoshi,
Due to the bending and stretching that occur during this process, such as rewinding during cutting and shipping, and pulling out from the drum during installation, the interlayer gap of the mixed cable causes uneven slipping of the insulating material tape. The damage caused by this is great, and this interlayer gap lowers the impulse and alternating current voltage resistance performance during actual use.

[Means to solve the problem]

Therefore, in order to solve the problem caused by mixing layers of different types of insulating materials as described above, the present invention aims to solve the problem that arises when a composite insulating material tape is wound on a conductor. When transitioning from a layer of material tape to a layer of composite insulating material tape of a different type, be sure to prepare a kraft paper tape in addition to both composite insulating material tapes on the same paper winding head, and first transfer the same type of composite insulating material tape to a layer of composite insulating material tape of a different type. A few sheets of the tape are wound, and on top of that, kraft paper tape and composite insulating material tape of different types or the same type of composite insulating material tape are alternately wound, and then only the composite insulating material tape of the different types is wound. , when the composite insulating material tape of a different type is further wound thereon, the tape is wound by the next paper wrapping head.
In the manufacturing method of OF cables, alternating layers of kraft paper, which has a particularly high cushioning effect, and the composite insulating material tape that has been wound so far are provided at the layer transitions that occur when layers of different composite insulating materials are mixed together. This is intended to solve the above-mentioned problems by forming a neutralizing layer.

The implementation of the present invention will now be described while further explaining the conventional method of winding the insulating layer of this type of cable.

Traditionally, OF cables have typically used thin insulating material with high impulse and AC pressure strength as a narrow tape on the conductor, and wider tapes with greater mechanical strength are used toward the outer layer. During this time, in one head of the paper winding machine, 10 to 20 tape bobbins of the same type, thickness, and width are prepared, and rotated around the cable core at the same speed, so that the insulating material tape is rolled in the same direction. Wound in layers.

To improve the bending and twisting characteristics of the cable,
Every other head changes the winding method: right, left, right, left. And the type and thickness of each required head,
The insulating material tape is wound in any one or a combination of widths to obtain the required insulation thickness with the full paper winding head in operation.

In the case of the 500kVOF cable mentioned above, according to the conventional winding method, the PPLP winding is finished and the outer layer PML
When moving to the winding of PPLP, the winding of PML naturally begins with the paper winding head next to the paper winding head at the end of the arranged PPLP winding, but in the present invention, the layer change between PPLP and PML is In one head, a composite insulation material tape of the same type as the composite insulation material tape that has been wound up to now (PPLP in this case) is first wound, and then a kraft paper tape and a different kind of composite insulation material that is wound on top of it are wrapped. material tape (in this case, PML) or the same type of composite insulation material tape that has been wound so far (in this case,
PPLP) is alternately wound, and then an insulating layer made of the previous dissimilar composite insulating material tape is wound thereon, and the dissimilar insulating tape is further wound, if necessary, by the paper winding head of the next stage or below.

The inventor of the present invention discovered that, in a single paper winding head, the layer change from one type of insulating material tape layer to a different type of insulating tape layer was performed using a composite insulating material tape of the same type as the composite insulating material tape that had been wound up to that point. An insulating layer formed by winding a composite insulating material tape of a different type on top of the insulating layer, and also in the same paper winding head with the above-mentioned layer change,
First, a tape of the same type of insulating material as the one type of insulating material tape that has been wound up to that point is wound, and then the same type of insulating material tape and a tape of a different type of insulating material are alternately wound, and then a different type of insulating material tape is wound on top of the same type of insulating material tape. We proposed an insulating layer formed by winding.

All of these insulating layers are used to eliminate the interlayer gap that occurs in this type of mixed cable without electrically causing problems, but as mentioned above, in the present invention, in particular, a cushion is provided on one side of the alternating windings. Using highly effective kraft paper,
This is a more skillful solution to the problem of interlayer gaps.

Among the many paper winding heads, for example, 20 tape bobbins of the paper winding head at the transition point between layers of different types of insulating tape are filled with PPLP tape (approx.
200μ) and a few composite insulating material tape bobbins, followed by kraft paper tape (approx. 200μ)
and the dissimilar composite insulating material tape that is then wound.
In other words, the PML tapes are fed out alternately.
A number of these tape bobbins and a number of bobbins of the above-mentioned different types of composite insulating material tape, ie, PML tape, are prepared.

Further, when alternate winding is performed using kraft paper and PPLP, a PPLP tape bobbin is prepared in place of the PML tape bobbin in the alternate winding.

The rotation of the main paper winding head relative to the cable core causes the paper to be wound by the previous paper winding head.
On top of the insulating layer of PPLP tape, several sheets of PPLP tape prepared in the main paper winding head are wound, and on top of that, kraft paper tape and PML tape are wound alternately in the same direction. If one layer each consists of one layer of kraft paper tape and one layer of PML tape, then
It is usually appropriate to have 1 to 3 sets. Furthermore, a few sheets of PML tape are wound in the same direction on top of this, completing the tape winding at this head. A system in which different types of composite insulating material tapes are prepared in one paper winding head in this way is called a mixed paper winding head.

The direction in which the insulating material tape is wound by the mixed paper winding head is opposite to the direction in which the insulating material tape is wound by the paper winding heads immediately before and after the mixed paper winding head.

FIG. 1 shows an example of an insulating layer wound by the method described above using the mixed paper winding head described above. An insulating layer is formed on the conductor 1 up to the paper winding head in the previous stage, usually by a plurality of PPLP tape heads, with a gap winding of about 30% each, and then, by a mixed paper winding head, the tape is wound with a gap of about 30%, first. A few layers of PPLP tape 2 are wound, and kraft paper tape 4 is placed on top of the outermost layer.
and PML tape 3 are similarly wound alternately in the same direction by gap winding, and the upper tape successively holds down the lower tape in the same direction, and then the PML tape 3 is wound on top of it.
A few pieces of tape 3 are wound in the same direction, and the next
The PML tape head winds the insulating layer of PML tape in the opposite direction.

Although the alternating layers (3+4) of kraft paper tape 4 and PML tape 3 are shown in the figure as only one set of layers, the number of layers of this layer, PPLP tape 2 alone, and PML tape 3 alone is permissible in one head. It can be changed arbitrarily within the range.

Assuming that the composite insulating material tape that is generally wound singly around the inner layer is B, and the composite insulating material tape that is wound singly around the outer layer is A, the present invention can be applied by using the same head, as will be fully understood from the above explanation. B
Layers are formed in the following order: Alone → A or B and kraft paper alternately wound → A alone.

As already explained, kraft paper has an extremely large cushioning effect, and even if there is a large difference in dryness loss, oil impregnation, swelling amount and swelling time characteristics between B and A during manufacturing, due to high temperature aging,
The inclusion of kraft paper and the cushioning effect of the natural fibers make it possible to produce cables with very good bending properties.

In reality, the number of kraft papers may be increased or decreased depending on the difference in characteristics between B and A. Furthermore, in order to improve the cushioning effect, it is effective to use thick kraft paper with as low density and airtightness as possible, for example, kraft paper with a thickness of about 150 to 200 μm.

The effects of the present invention have been almost confirmed through subsequent trial production and testing of the 154 kV cable mentioned above, and the effect is sufficiently exhibited in the 500 kV cable, making it possible to obtain a high-quality ultra-high voltage OF cable.

The above explanation has mainly been about OF cables with PPLP as the inner layer and PML as the outer layer.
In addition to PPLP and OF cables whose outer layer is FEP, it can be applied to OF cables where the inner layer and outer layer are made of different composite material tapes to form an insulating layer, etc. at the layer transition point.

〔Effect of the invention〕

As already explained, since the present invention uses kraft paper for one side of the alternate wrapping with the composite insulating material tape in the mixed head, the cushioning effect of the kraft paper reduces the drying loss of the composite insulating material tape during manufacturing. Even if there are large differences in the amount of swelling due to oil impregnation, high temperature aging, and swelling time characteristics, cables with good bending properties can be made with the inclusion of kraft paper.

In addition, it is possible to obtain an OF cable with less tape swelling and no deterioration in impulse and AC withstand voltage performance.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the formation of layer transitions in a tape of different insulating materials according to the manufacturing method of the present invention. 1... Conductor, 2... PPLP insulation material tape, 3
...PML insulation material tape, 4...Kraft paper tape.

Claims (1)

[Claims] 1. In an OF cable that mixes different types of insulating material tape layer by layer as the insulating material, the layer change from one type of composite insulating material tape layer to a different type of composite insulating material tape layer is done in one paper wrapping head. In this method, kraft paper tape and the different types of insulating material tape or the type of insulating material tape are alternately wound on the one type of insulating material tape, and then the different type of insulating material tape is further wound thereon. A method for manufacturing an OF cable, characterized in that the OF cable is formed by: