JPH0413935B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a connecting portion of an OF cable in which multiple layers of insulating materials having different specific resistances are applied on a cable conductor.

Conventional OF cables have one type of insulating paper (for example, low-loss paper) that constitutes the insulating layer.

Recently, however, laminated paper, which is made by pasting kraft paper on one or both sides of a plastic film, has come into use for purposes such as increasing capacity. OF cables with a multilayer insulation structure that also uses

In this case, since the DC resistivity of laminated paper is orders of magnitude higher than that of conventional low-loss paper, the electric field during DC withstand voltage, which is carried out after the completion of on-site installation work, will have a resistance distribution, so almost all of the electric field will be The burden will be shared by laminated paper, which has a high specific resistance. Therefore, the connection part also requires a connection part reinforcing and insulating structure that is adapted to the potential distribution of the cable main body.

However, with the conventional connection reinforcement insulation structure, that is, the insulation reinforcement layer is made of only a single insulating paper (low-loss paper), and a single stress control cone is formed on the periphery of the insulation reinforcing layer. , cannot satisfy such requirements.

The purpose of the present invention is to provide a connection structure that makes it possible to alleviate the DC electric field distribution that cannot be solved with the conventional structure described above, and to make it possible to put into practical use an OF cable that has a multilayer insulation structure consisting of a low-loss paper layer and a laminated paper layer. Our goal is to provide the following.

The gist of the present invention is to provide a multilayer insulation structure having, on a cable conductor, an inner cable insulation layer made of a plastic film-kraft paper laminate paper wrapping layer having different DC resistivities, and an outer cable insulation layer made of a low-loss paper wrapping layer. At the connection part of OF cables with different layer insulation, the connection part reinforcing insulating layer covering the cable conductor connection part of both cables, which is obtained by sequentially stripping the cable insulation outer layer and the cable insulation inner layer, is applied to the cable conductor connection part and both cable insulation inner layers. A connection reinforcing insulating inner layer consisting of a plastic film-kraft paper laminate paper winding layer is formed on these circumferences, spanning this connection reinforcing insulating inner layer and both cable insulating outer layers. It consists of an outer connection reinforcing insulating layer made of a low-loss paper-wrapped layer, and a stress control cone for direct current electric field formed between the inner reinforcing insulating layer for reinforcing the connection and the outer layer reinforcing the insulating connection layer. .

FIG. 1 shows a specific embodiment of the present invention.

1 is a cable conductor, 2 is an inner cable insulation layer made of a plastic film-kraft paper laminate paper wrapping layer, and 3 is an outer cable insulation layer made of a low-loss paper wrapping layer. Reference numeral 4 denotes a connecting sleeve for the cable conductor 1, and 5 refers to a connecting portion reinforcing insulation consisting of a plastic film-kraft paper laminate and paper wrapping layer formed on the circumference of the connecting portion of the cable conductor 1 and both cable insulation inner layers 2. An inner layer 6 is a connection reinforcing insulating outer layer consisting of a low-loss paper wrapping layer formed on the periphery of this connection reinforcing inner insulating layer 5 and both cable insulating outer layers 3, 7 is a shielding layer, and 8 is this connection reinforcing insulating outer layer. This is a stress control cone for the DC electric field formed at the interface between the connection portion reinforcing insulating inner layer 5 and the connection portion reinforcing insulating outer layer 6. A stress control cone 9 is the same as the conventional connection part, and is formed on the circumference of the connection part reinforcing insulating outer layer 6. 10 is insulating oil, 11 is a junction box, 12 is a junction box end seal, and 13 is a cable aluminum coating.

The biggest feature of this embodiment is that the connection is reinforced by two types of insulation layers: an inner connection reinforcement insulating layer 5 made of a plastic film-kraft paper laminate paper wrapping layer and an outer connection reinforcement insulation layer 6 made of a low-loss paper wrapping layer. This is because an insulating layer is formed and a direct current stress control cone 8 is provided between the inner and outer layers.

Next, the effects obtained by the connection part reinforcing insulating inner layer 5, the connection part reinforcing insulating outer layer 6, and the stress control cone 8 will be explained with reference to FIGS. 2 and 3.

FIG. 2 shows the distribution of equipotential lines E when a commercial frequency voltage or an impulse voltage is applied. in this case,
Due to the capacitance distribution, there is no large difference in dielectric constant,
The connection portion reinforcing insulating inner layer 5 and the connection portion reinforcing insulating outer layer 6 are well balanced, and both share the electric field.

Figure 3 shows the distribution of equipotential lines E when a DC voltage is applied to this connection. In this case, the electric field becomes a resistance distribution, and is made of a plastic film-kraft paper laminate paper wrapping layer with a high specific resistance. It can be seen that the connection part reinforcing insulating inner layer 5 takes up most of the burden.

It is clearly seen that the DC stress control cone 8 between the inner and outer layers works effectively to smoothly distribute the DC electric field.

As described above, according to the present invention, the connection part reinforcing insulating layer is made of a plastic film-kraft paper laminate paper wrapping layer formed on the periphery of the cable conductor connection part and both cable insulation inner layers. A reinforcing insulating inner layer, a connecting part reinforcing insulating outer layer consisting of a low-loss paper wrapping layer formed on the periphery of this connecting part reinforcing insulating inner layer and both cable insulating outer layers, and a connection part with this connecting part reinforcing insulating inner layer. The reinforcement consists of a stress control cone against the DC electric field formed between the reinforcing outer layers, so when the DC withstand voltage is applied, the connection part is reinforced by the plastic film-kraft paper laminate paper wrapping layer with high specific resistance. The insulating inner layer shares the electric field, and the DC stress control cone acts to alleviate the electric field. As a result, excellent electrical performance can be expected at the connection part of the multi-layer, dissimilarly insulated OF cable with the multi-layer insulation structure described above, and its practical application will become possible.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the connecting portion of the present invention, and FIG. 2 is an explanatory diagram showing the distribution of equipotential lines when a commercial frequency voltage and an impulse voltage are applied to the connecting portion according to the present invention. FIG. 3 is an explanatory diagram showing the distribution of equipotential lines when a DC voltage is applied to the connection portion according to the present invention. 1: Cable conductor, 2: Inner cable insulation layer consisting of plastic film-kraft paper laminate paper winding layer, 3: Cable insulation outer layer consisting of low-loss paper winding layer, 4: Connection sleeve, 5: Plastic film-kraft paper laminate paper winding. Connection reinforcing insulating inner layer consisting of layers, 6; Connection reinforcing insulating outer layer consisting of a low-loss paper wrapping layer, 7; Shielding layer, 8; Stress control cone for direct current, 9; Stress control cone same as conventional connection, 10 ;
Insulating oil, 11; Junction box, 12; Junction box end seal, 13; Cable aluminum coating, E: Equipotential wire.

Claims (1)

[Claims] 1. A multi-layer dissimilar insulated OF cable with a multi-layer insulation structure, which has, on the cable conductor, an inner cable insulation layer consisting of a plastic film-kraft paper laminate paper wrapping layer each having a different DC resistivity, and an outer cable insulation layer consisting of a low-loss paper wrapping layer. At the connection part, the connection part reinforcing insulating layer covering the cable conductor connection part of both cables from which the above-mentioned cable insulation outer layer and cable insulation inner layer are sequentially peeled off extends over the cable conductor connection part and both cable insulation inner layers. A connection reinforcing insulating inner layer consisting of a plastic film-kraft paper laminate paper winding layer formed on the circumference of the cable, and a low-loss cable formed on the circumference of the connecting part reinforcing insulating inner layer and both cable insulating outer layers. A multi-layer heterogeneous product comprising a connection reinforcing insulating outer layer made of a paper-wrapped layer, and a stress control cone for direct current electric field formed between the connecting part reinforcing insulating inner layer and the connecting part reinforcing insulating outer layer. Connection part for insulated OF cable.