JPS58111209A - Power cable - 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 The present invention relates to a novel cable structure in which a special 1cOF electric cable and a cross-linked polyethylene cable are combined.

In recent years, with the rise in power transmission voltage, various studies have been conducted on the insulation structure of power cables, but the main ones are those that have a laminate structure by laminating insulating paper tape and polyolefin tape such as polyethylene or polypropylene, or polyolefin. Currently, mixed paper in which iron fibers are mixed with cellulose is being pursued, and no new attempts have been made to improve conventional electrical cables.

When paper is made of plastic laminate or mixed paper as an insulator, ξ = 2.4 to 2.5 tan δ (%) =
To achieve 0.06 to 0.08, the plastic fraction should be 6.
0 or more is required, and since these are always kept in an oil-soaked state, it is almost impossible to ensure flooding due to the swelling and dissolution of plastics due to oil, or the walls of oil passages, etc. 2-, ri s Nothing has been developed for commercial use yet. Also, even if it is confusing from a manufacturing point of view, is it placed from the υru family stage? i
There are many cases where L is required, and it is inevitable that the cost will be high.

For this reason, the present inventors have developed and already proposed an electrical cable that combines oil-impregnated paper insulation JVI and a cross-linked polyethylene insulation layer, but in particular, oil-impregnated paper (semi-synthetic paper) has been proposed. If it is applicable to paper insulation, it is possible to further improve the strength characteristics and obtain a low-loss power cable.

That is, one of the inventive cable caples has an oil-impregnated paper insulating layer on the body side and a cross-linked polyethylene insulating layer on the outside side.
In particular, the inner cable is constructed by using low-loss semi-synthetic paper as the oil-impregnated paper insulation layer, and providing an oil-resistant plastic coating layer between the oil-impregnated laminated insulation layer and the cross-linked polyethylene insulation layer. The oil-immersed insulating layer is made of semi-synthetic paper, and the dielectric constant is 12.7 to 2.8 due to K. @ Electric tangent t
and δ (%) o, o6 to 0.08, and using this, the cable's ε total 2, which was impossible with conventional OF cables, was achieved.
．． 4-2.6. Tan δ (chi) is set to 0.04 to 0.06 to create an extremely low-loss cable, and the stress distribution is made uniform by grading of ε to reduce the working stress of the oil-immersed insulation layer and cross-linked polyethylene insulation layer to 11 K.
No stress below V/-, insulation thickness is 33■ (500KV
It has been extremely successful in increasing the number of cables (such as thickening), and since it is used under pressure, it has various effects such as preventing the formation of water trees that tend to occur with ordinary cross-linked polyethylene cables. .

Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows one embodiment of the electric bracket and nibble of the present invention, where 1 is an oil passage and 2 is a conductor such as steel or aluminum.

3 is a conductor shielding layer for making the conductor surface smooth and equipotential; 1 is made of, for example, Kazen paper or metallized paper. 4 is plastic flakes or fibers such as polypropylene flakes or fibers or polybenthene flakes or fibers, and cellulose fI1. The oil-impregnated paper insulating layer 5 is made of mixed paper (semi-synthetic paper) or polypropylene laminated paper mixed into the fiber, and 6 is a cross-linked polyethylene 'vv'. 7 is an external protection plate made of a four-electrode silicone stick, etc. (J*i); 8 is an external protection plate TJ made of a metal sheath and anticorrosive material.

When manufacturing such a cable, a rolling paper of semi-synthetic paper, for example, is wrapped around the outside of the conductor in the same way as in normal OF cable manufacturing. A cable core is manufactured by extruding and covering the outer semi-conducting layer with Kazenblack connosound for three layers, continuously crosslinking polyethylene in a crosslinking cylinder, and cooling it, followed by ordinary O O
It can be manufactured by drying, dehydrating, and impregnating semi-synthetic paper in the core with oil in the same manner as in the case of manufacturing the F cable. The external protective coating may be formed by extrusion coating of aluminum corrugate or vinyl chloride resin at the final stage.

As described above, since the present invention has a single layer of oil-impregnated semi-synthetic paper on the inside and a cross-linked/reethylene insulation layer on the outside, the electrically stressed portion of the conductor side can be electrically Constructed of an oil-immersed insulating layer with excellent stability, the part away from the conductor is electrically shielded with a 4'% dielectric tangent tan δ.
Constructed with an excellent cross-linked polyethylene insulation layer,
Dielectric loss and allowable current K can be considerably improved by 1%.Since semi-synthetic paper is used as the oil-immersed insulating layer, e2.7 tan8 (%) 0.06 of semi-synthetic paper can be reduced to 1, for example, total insulation is 2.
Divide the equivalent galvanic rate from K to 2.4 to 2.6, t
an δ (%) of 0.04 to 0.06 can be achieved, and this value is less than I of oil-impregnated paper, and the dielectric constant of normal oil-impregnated paper and cross-linked polyethylene is 2.6 to 2.8. , ta
The cable has an even lower loss than nδ (ch) 0.06 to 0.08.

Also, the blurred semi-synthetic paper oil-immersed insulating layer and the cross-linked polyethylene insulating layer are graded K because they are graded e.

The working stress of the OF insulating layer and the crosslinked polyethylene layer is i KV/, and the insulating layer is 33 m with the stress below.
m (no match of 500KV cable) and λ
).

Also, since the thickness of the Cv part is 16 to 23 mm without using a certain thick wall (Q), which is difficult in the mixing technique with 500 KV cable, it can be used with 66 KV to 154 KV'CV cable, which has a proven track record. Reliability is also behind.

Furthermore, due to pressurization, there was no decrease in the V- characteristics (fJ2 and J) seen in ordinary cross-linked polyethylene cables, and no water trees occurred.

In the same figure, line C is 500KV, 2500-cable V-t% AI estimated from the experiment of the model cable of the present invention.
vI! d Conventional 500KV, 2500j (2) Characteristics of OF cable V-, B line is 500KV.

The V- of the 2500- C ■ cable shows the ox a, and it can be seen that the characteristics of the uninvented cable are favorable at first glance. However, in the above, the OF cable is oil-impregnated paper 33 m thick.

The Cv cable has a 0V 45cm thickness and the cable of the present invention has a total insulation layer thickness of 33cm.

In addition, the electric power caple of the present invention 66KVIX200+aj 7 semi-synthetic paper oil-impregnated paper layer thickness 2.7, cross-linked polyethylene layer thickness 4.
Even in the results of a two-year long-term test with 3-, no occurrence of water tree was observed.

As described above, the electric cable according to the present invention is a cable with excellent long-term stability, and has reduced thermal expansion and improved thermal and mechanical properties compared to conventional Ov cables.
This book provides a cable with even lower loss than the 0F-eV composite cable that the present inventors have already developed.

The power cable of the present invention does not necessarily require a metal sheath like a normal OF cable, has good flexibility, is relatively lightweight, and is easy to handle.Furthermore, since the outer layer insulation is crosslinked polyethylene, it has excellent chemical resistance. It is something that exists.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the power cable of the present invention.
FIG. 2 is a graph showing the V- characteristics of the cable. 1 oil passage, 2 conductors, 3 conductor interconnection layers, 4 semi-synthetic paper oil-impregnated paper insulation layers, 5 oil-resistant plastic layers. 6. Cross-linked polyethylene insulation layer, 7. External retardation layer, 8. External protected layer Patent applicant: Fujikura Electric Cable Co., Ltd. Representative Patent attorney: Mamoru Takeuchi

Claims (1)

[Claims] An electric cable characterized in that an oil-impregnated paper insulating layer made of semi-synthetic paper, an oil-resistant plastic coating layer, and a cross-linked polyethylene insulating layer are sequentially provided on the outer periphery of a conductor having an oil passage in the center.