SU1424061A1 - A.c. high-voltage cable - Google Patents

Abstract

The invention relates to electrical engineering, in particular to cable technology. The purpose of the invention is to increase the electrical strength of the cable by reducing the intensity of the electric field near the conductor of the neck of the core. The cable contains a conductor, insulation, electrically conductive shields on top of the conductor and the insulation and sheath. Insulation is made of ribbons with lower and lower dielectric constant values superimposed with a certain alternation. 4 il. g O)

Description

The invention relates to power cables with tape insulation, in particular to oil-filled cables.

The purpose of the invention is to increase the electrical strength of the cable by reducing the intensity of the electric field near the conductor of the neck of the core.

Fig l shows cable, general view; in fig. 2 - its insulation structure; FIG. 3 shows the change in the dielectric constant over the thickness of the insulation; in fig. 4 shows the distribution of the electrical field and the electric field in the cable insulation.

The cable contains a conductor I, electrically conductive screens 2 along the conductor and insulation, insulation 3 and sheath 4. Insulation 3 is made of tapes with increased 5 and reduced 6 values of dielectric constant.

Consider two types of paper ribbons with characteristics b and 5jj, respectively (let j Eji). Insulation made of type 1 tapes has a dielectric constant t, i of only type 11 tapes - 2 it is obvious that,. Consider further the insulation made of an equal number of both types of tapes alternating with each other. on the other, in the following way: one tape of the 1st type, then one tape of the 11th type, then again of the 1st, one of the 11th, and so on. This insulation structure is intermediate in relation to the two considered: it satisfies the condition

e, e, e, j

Let the ratio of alternating tapes be one to two. In this case, the insulating structure is as follows: two high-voltage alternating current cables containing a conductive core, on top of which an electrically conductive shield is sequentially superimposed, graded insulation, formed by two types of tapes with different values of dielectric permittivity and consisting at least two layers, and a screen, oh h with the fact that, in order to increase the electrical strength

you are type 1, one type 11 tape, white by reducing the tension

two 1st, one 11th, etc. E such insulation is within

e.

the electric field near the conductive core, at least some of the layers located near the conductors of the neck of the core, is made of alternating tapes with different values of dielectric permittivity, and the number of tapes with a large dielectric permittivity value when passing to each subsequent from the core to the insulation layer decreases.

The ratio of alternating tapes to me is a series of insulating structures, the characteristics of which smoothly vary from 8, to, depending on N - the ratio of the number of tapes

ten

42406 2

1-type to the total number of tapes in the insulating structure.

These structures can be combined in one in the form of successively applied insulation layers, if the cable is insulated from alternating tapes of both types and differing from each other in N, i.e. according to the ratio of tapes with different. Given any dependence of N on the tech- nal radius of the insulation r, one gets the distribution of permeability E (r) corresponding to it (Fig. 3, curves

15 8) ensuring in this way

the ability to control the intensity of the electric field (Fig. 4, curves 9,10). Moreover, the greater the ratio Cj / 6jj and, / f, the wider

2Q possibility of such regulation. By requiring, for example, B (d) to vary inversely with the radius, a uniform distribution of the floor is ensured over the entire thickness of the insulation or its part (Fig. 4, curve 9).

The use of the proposed cable provides an increase in the electrical strength of the cable by reducing

30 of the electric field strength at the conductor core.

25

Claims (1)

Invention Formula An AC high voltage cable containing a conductive core, over which an electrically conducting shield is sequentially superimposed, gradated insulation formed by two types of tapes with different dielectric constant values and consisting of at least two layers, and a shield about l and h this is due to the fact that, in order to increase the electrical strength of the cable by reducing the voltage the electric field at the conductive core, at least part of the layers located near the conductor of the neck of the core, is made of alternating tapes with different dielectric constant values, and the number of strips with a high dielectric constant value when going to each subsequent insulation layer from the core is decreasing. Cpu.1 L FIG. 2 ( fO