JPH02273414A - Oil immersed insulation tape wound power cable - Google Patents

Abstract

PURPOSE:To improve withstand-voltage by making at least one side of the insulating tapes coming in contact with a layer, whose winding direction of an insulating tape winding layer changes, to be of the same with, or thinner than the thin thickness of each tape thickness of the contacting layer. CONSTITUTION:An insulation tape wound layer 12a consists of a plurality of sheets of insulating tapes of the thickness t1 and each tape thereof is gap-wound, while each tape is wound up so that gaps may not overlapped. The insulating tape wound layer 12b consists of a plurality of sheets of the insulating tapes having the thickness t2 and the insulating tapes, whose innermost layer is of the thickness t3, while each tape is wound up by gap winding so that gaps may not overlap. That is, an oil gap (t1+t2), (t2+t3) or 2t3 of the gap overlapping part, where the winding direction of the insulating tape winding layer becomes in either case smaller than (t1+t2) so that absolute bearing force of that part can be made bigger than the former one.

Description

[Detailed Description of the Invention] [Industrial Application Fields] This invention is applicable to SL cables, OF cables,
The present invention relates to an oil-impregnated insulating tape-wrapped power cable having an insulating tape-wrapped insulating layer made of insulating paper, synthetic paper, semi-synthetic paper, etc. impregnated with insulating oil.

Conventional technology In conventional power cables wrapped with pond-immersed insulating paper tape such as S L cables, OF cables, and POF cables, in order to improve withstand voltage, insulating paper of several thicknesses, such as 50
0KV OF cable is 120μm, 170μm, 2
Use 20 μm semi-synthetic paper, with thin insulating paper near the conductor,
An insulating layer with a cladding configuration is used, with the insulating paper becoming progressively thicker towards the outside. This is done because the potential gradient is high near the conductor, the dielectric strength is lower at the curved part of the insulation than at the insulation paper part, and furthermore, thin insulation paper has a higher density than thick insulation paper. By using thin insulating paper near the conductor where the potential gradient is large, the amount of insulating paper is increased, the amount of insulating oil with low dielectric strength is reduced, and the thickness of the oil film caused by gap winding is reduced. By reducing the thickness of the cable (generally, the dielectric strength of an insulator is approximately inversely proportional to its thickness) and increasing the dielectric strength of that part, the cable's withstand voltage is improved.

Also, the mechanical properties of the cable, such as the flexibility of the cable,
In order to prevent paper breakage due to bending, etc., insulating paper is layered every few to 10 or so sheets, and within each layer, wrap in the same direction with gaps so that the gaps do not form directly, and wrap each layer separately. Ten or so layers are wound in a so-called alternating manner, with one direction reversed. That is, as shown in FIG. 2, several to ten-odd sheets of insulating paper are wrapped around the outer periphery of the conductor 21 in the same direction with gaps so that the gaps do not overlap, and each layer 22a is wrapped with insulating tape.
, 22b, 22c, 22d --- windings of insulating paper (=J
The insulating layer 22 is formed by sequentially stacking the layers in a reverse 1:1 direction and impregnating or filling the layers with an insulating layer 411. In the figure, 23 is a conductor shielding layer applied directly above the conductor 21, and 24 is an external covering including an insulating shielding layer applied around the outside of the insulating layer 22.

1. Problems to be Solved by the Invention] In conventional oil-immersed insulating tape-wrapped power cables such as Niki's, several layers or several layers of insulating paper tape are alternately wound, and the number of windings of each layer ( ) At the part where the direction changes, the thickness of the oil gap becomes larger than in other parts.

That is, as shown in Figure 3, the thickness of the insulating paper tape is 1
．． Insulating paper tape wrapping layer 32 made by gap-wrapping multiple sheets of
When a plurality of sheets of insulating paper tape having a thickness t2 are laminated on top of the insulating paper tape wrapping layer 321, which is gap-wound in the opposite direction to the wrapping direction of the second layer 32a, the winding direction changes. Both insulating paper tapes that come into contact at portion A-A intersect, and in the gap portion of each gap winding, there is a portion where both gaps G, , G overlap. In layers of insulating paper tape wound in the same direction, the thickness of the gap is tl or [, but in the area where gaps GG and GG overlap, the thickness of the gap is (L1 + t2)a,
The oil gap is larger than the oil gap in other gap portions of the insulating paper tape, and therefore this portion is electrically weaker than other portions.

In addition, in the part bar A where the wrapping j'J direction of the insulating paper tape changes, the insulating paper tapes that are in contact with each other intersect, and this intersecting part is more adaptable to the bending of the cable than the part in the same direction. As you can see, the compatibility is poor, and paper breaks are more likely to occur in the areas where the edges of the paper tape intersect than in other areas. In particular, where the paper thickness changes and the edges intersect, thin paper is more likely to break than thicker paper, and the thinner paper is more likely to tear, which is a mechanical weakness.

One aspect of this invention is to improve electrical performance by eliminating the above-mentioned electrical weaknesses, and the other is to solve the above-mentioned electrical weaknesses. The first aspect of this invention is to improve the performance of both by eliminating mechanical weaknesses. This is a power cable in which the thickness of the insulating tape of the layers in contact with each other is the same as or thinner than that of the thinner layer, and the second one of the present invention is a gap-wound power cable. A power cable in which both insulating tapes in contact with the layer in which the winding direction changes in the insulating tape wrapping layer have the same thickness and are thinner than the thickness of the insulating tape of those layers, and furthermore, this invention The second another is a power cable in which both insulating tapes in contact with the layer in which the winding direction of the insulating tape wrapping layer changes are the thinnest insulating tapes used for the insulating layer of this cable. .

[Function] In one power cable of the present invention, at least one of the insulating tapes in contact with the layer in which the winding direction of the insulating tape winding layer changes is equal to or thinner than the thinner of the tapes in the contacting layer. Since the thickness of the oil cap is also thinner, the thickness of the oil cap where the winding direction changes and the tape intersects is thinner than that of a conventional oil cap.

In another power cable of the present invention, the winding direction of the insulating tape layer is changed, and both insulating tapes in contact with the helical layer are
Since the thickness is thinner than the thickness of the insulating tape of those layers, the thickness of the oil cap at the part where the winding direction changes and the tape intersects is even thinner than the conventional one. Since the thickness is the same, both insulating tapes conform to the bending of the cable in the same way.

In yet another power cable of the present invention, both of the insulating tapes have the same thickness as the thinnest insulating tape used for the cable, so that the winding direction changes and the tapes intersect. The thickness of the oil gap at the part (J, from the innermost layer to the outermost layer of the insulating layer is the same as the oil gap of the thinnest innermost layer, and 1) at the part where the winding direction of the layers changes. The degree of adaptability of the insulating tape to the bending of the cable is the same.

Embodiment] An embodiment of the power cable of the present invention will be described with reference to FIG. FIGS. 1A and 1B are longitudinal cross-sectional views showing a portion of the insulating layer, particularly a portion of the layer where the winding direction of the insulating tape changes.

First, one power cable of the present invention will be described with reference to FIG. This is a layer of insulation tape wrapped around it. Insulating tape wrapping layer 1.2. A is composed of a plurality of sheets of insulating tape having a thickness of t, each of which is gap-wound, and each tape is wound so that the gaps do not overlap. The insulating tape wrapping layer I21) consists of a plurality of insulating tapes with a thickness of t2 and an insulating tape with an innermost layer of thickness L, and each tape is wound in a gap in the same way as above so that the gaps do not overlap. It's rolled up.

At angle r in this figure, the relationship between the thicknesses of each insulating tape is t,>
The case where tl > t3 is shown, but
This is true and > tl = i3 and 6 is good. In addition, here, an insulating tape with a thickness of L3 is wrapped in the tape-wrapped layer 121.
] side is shown, but 1. > 1.
], the insulating tape with a thickness of L3 may be provided on the side of the tape wrapping layer 12a or on both sides.

Furthermore, it goes without saying that t, = t, > L+ in a portion where the thickness of the tape on both sides is the same where the winding direction of the layer changes.

According to the above embodiment, the oil gear c tl in the overlapping part of the gap where the winding direction of the insulating tape winding layer changes
-4-t3), (t2+tl or (J is both smaller than (t, 1-t2), so the dielectric strength of that part) can be made larger than that of the conventional one.

Next, another embodiment of the power cable of the present invention will be described with reference to FIG. 1(b). In this embodiment, the insulating tapes in contact with each layer in the portion where the winding direction of the insulating tape layer changes are made to have the same thickness and are thinner than the thickness of the insulating tape of each layer. 12 (J oil-immersed insulation layer, !2a, t) Some insulation tape wrapped layer therein, 1
21] is an insulating tape wrapping layer applied around the outer circumference adjacent to it. The insulating tape wrapping layer 12g consists of multiple layers of insulating tape with a thickness of tl and the thickness of the outermost layer 11. Each tape is gap-wound and burnt so that the gaps do not overlap.

The insulating tape wrapping layer 121) consists of a plurality of insulating tapes with a thickness of L2 and an insulating tape with an innermost layer of thickness t, and each tape is wound in a gap manner so that the gaps do not overlap in the same way as above. It is being

This example is for the case where the insulating tapes of thicknesses L3 and t4 are equal in thickness and are thinner than the insulating tapes of thicknesses t and t, as shown in the drawing.

> 1. is shown, but this may also be 12=1°.

According to the above embodiment, the thickness of the oil gap at the overlapping part of the gap where the winding direction of the insulating tape winding layer changes is 2.
Since tq or 2t4 is smaller than (t+-t-t,), the dielectric strength can be made larger than that of the conventional one. Also, the thickness of the insulating tape on both sides of the part where the winding direction changes is 13=1. Therefore, both tapes have the same adaptability to cable bending, and therefore only one tape will not be adversely affected.

Next, yet another embodiment of the power cable of the present invention will be described. This is the example described in “-”, i.e. the first
In the figure (b), the thicknesses of the insulating tapes with thicknesses t3 and L4 are the same as the insulating tape with the minimum thickness used for the insulating layer. By doing so, it is possible to minimize the thickness of the oil gap over the entire insulating layer where the tape gaps overlap in the portion where the winding direction changes, thereby further improving the withstand voltage of the cable.

[Effects of the Invention] According to one power cable of the present invention, the thickness of the oil gap at the overlapped portion of the gap in which the winding direction of each insulating tape winding layer in which a plurality of insulating tapes are gap-wound is changed. Even in this case, the insulating oil portion, which has a relatively small dielectric strength, can be made thinner than the conventional one, so the withstand voltage of the cable can be improved.

Furthermore, according to another power cable of this invention,
In addition to the direc- tion of withstand voltage mentioned above, both insulating tapes that touch the part where the winding direction of the insulating tape winding layer changes are made to have the same thickness, so they both adapt to the bending of the cable in the same way. Therefore, compared to the case of conventional cables, the poor adhesion of one insulating tape to the other insulating tape does not have an adverse effect on the other insulating tape, such as paper breakage, and the mechanical performance of the cable can be improved. can.

According to yet another invention of the present invention, in addition to the above-mentioned improvement in mechanical performance, the insulating tape used in the cable is also Since the cable has the thinnest thickness, the oil gap in that area is the smallest over the entire insulation layer of the cable, thus minimizing the electrical weakness caused by the oil gap.

[Brief explanation of drawings]

1(a) and 1(b) are longitudinal cross-sectional views of a portion of the insulating layer of different embodiments of the power cable of the present invention, and FIG.
The figure is a longitudinal cross-sectional view of a portion of an insulating layer of a conventional power cable. Gap, Δ-A The part where the winding direction of the insulation tape layer changes.

Claims (3)

[Claims] (1) In a power cable having an insulating layer formed by wrapping an insulating tape on a conductor and impregnating it with insulating oil, at least one of the insulating tapes in contact with the layer whose winding direction changes in the gap-wound insulating tape layer. , an oil-immersed insulating tape-wrapped power cable having a thickness equal to or thinner than the thinner of the thicknesses of the respective insulating tapes of their contacting layers. (2) In a power cable having an insulating layer in which insulating tape is wound on a conductor and impregnated with insulating oil, both insulating tapes in contact with the layer in which the winding direction changes of the gap-wound insulating tape layer are An oil-immersed insulating tape-wrapped power cable characterized in that the cable has the same thickness and is thinner than the thickness of each insulating tape of the layers. (3) Oil-immersed insulating tape winding power, characterized in that both insulating tapes in contact with the layer whose winding direction changes in the insulating tape-wrapped layer according to claim 2 have the thinnest thickness of the insulating tapes in the insulating layer. cable.