High-voltage cable

Abstract

A high-voltage cable for electrostatically charging a coating agent in an electrostatic coating plant is provided. The cable includes a centrally arranged cable core and an electrically insulating jacket which sheaths the cable core. The cable core has a moderate electrical resistance according to the principles of the present disclosure. The cable core includes fibers that form a non-woven fabric, and at least one strip of the non-woven fabric of the cable core is twisted.

Claims

1. A high-voltage cable for charging a coating agent in an electrostatic coating plant, the cable comprising: a radially central cable core consisting of a plurality of twisted strips of nonwoven fabric, each strip of nonwoven fabric composed of a plurality of electrically conductive filaments, the cable core having an electrical resistance in the range of 10 k/m-100 k/m; a first electrically insulating jacket layer sheathing the cable core; an electrical shield layer surrounding the first electrically insulating jacket layer, the electrical shield layer having an electrical resistance less than the electrical resistance of the cable core; and a field smoothing element sheathing the cable core at junctions spaced from each other along the cable, the field-smoothing element arranged between the cable core and the first electrically insulating jacket layer, the field-smoothing element lying directly on the twisted strips of the cable core.

2. The high-voltage cable of claim 1, wherein the filaments each include an electrically insulating material impregnated with electrically conductive carbon, the fabric having a moderate electrical resistance configured for use in an electrostatic coating plant for electrostatically charging a coating agent.

3. The high-voltage cable of claim 1, wherein at least part of the filament is made of an electrically conductive plastics material.

4. The high-voltage cable of claim 1, wherein the nonwoven fabric strips of the cable core are configured with a coarseness for providing gaps therebetween, respectively, the gaps substantially limiting capillary forces thereat to be substantially insufficient to draw petroleum jelly into the gaps.

5. The high-voltage cable of claim 1, wherein the nonwoven fabric strips are twisted sufficiently tightly to be substantially free of gaps between the strips thereof.

6. The high-voltage cable of claim 1, wherein the field-smoothing element is made of a plastics material.

7. The high-voltage cable according to claim 6, wherein the plastics material is polyolefin.

8. The high-voltage cable of claim 1, wherein the field-smoothing element has a moderate electrical resistance configured for use in an electrostatic coating plant for electrostatically charging a coating agent, and the electrical resistance of the field-smoothing element is greater than the electrical resistance of the cable core, and the electrical resistance of the field-smoothing element is less than an electrical resistance of the first electrically insulating jacket layer.

9. The high-voltage cable of claim 1, further comprising: an electrically insulating outer jacket sheathing the cable core, the first electrically insulating jacket layer and the electrical shield layer.

10. The high-voltage cable according to claim 9, wherein the outer jacket is made of a plastics material.

11. The high-voltage cable of claim 1, wherein the first electrically insulating jacket layer is made of a plastics material, and the cable includes a second electrically insulating jacket layer coaxial to the first electrically insulating jacket layer.

12. The high-voltage cable of claim 1, wherein one or more of the plurality of electrically conductive filaments abut the field smoothing element.

Description

DRAWINGS

(1) Other advantageous developments of the disclosure are characterized are explained in greater detail below with reference to the description of exemplary embodiments in conjunction with the figures, in which:

(2) FIG. 1 is a cross-sectional view of a conventional high-voltage cable containing a cable core made of copper;

(3) FIG. 2 is a cross-sectional view of a conventional high-voltage cable containing an electrically insulating cable core having an electrically conductive coating;

(4) FIG. 3 is a cross-sectional view of a high-voltage cable according to the principles of the present disclosure containing an electrically conductive cable core;

(5) FIG. 4 is a cross-sectional view of an alternative high-voltage cable according to the principles of the present disclosure comprising an additional shield; and

(6) FIG. 5 is a schematic diagram of an apparatus according to the disclosure for charging a coating agent.

(7) FIG. 6 is a side view of the high-voltage cable including a field-smoothing element surrounding the cable core at junctions along the high-voltage cable.

DETAILED DESCRIPTION

(8) FIG. 3 shows an exemplary embodiment of a high-voltage cable 1C according to the disclosure, which corresponds in part to the high-voltage cable 1B described above and depicted in FIG. 2, and therefore to avoid repetition, reference is made to the above description, with the similarly numbered reference signs being used for corresponding features.

(9) A distinct feature of this exemplary embodiment according to the present disclosure is the design and construction of the cable core 2C. The cable core 2C here consists of twisted strips of nonwoven fabric, which each consist of a plurality of filaments (fibers) and are made electrically conductive. Thus the cable core 2C is made of a plastics material as a support material, which is made electrically conductive, for instance by filling or coating with carbon particulates. Thus the cable core 2C has a moderate electrical resistance in the range of, e.g., 10 kWm-100 kWm.

(10) Forming the cable core 2C from twisted strips of nonwoven fabric, in contrast with the conventional high-voltage cable 1B shown in FIG. 2, inhibits the permeating petroleum jelly from affecting the electrical conductivity of the high-voltage cable 1C.

(11) The moderate electrical resistance of the cable core 2C, in contrast with the conventional high-voltage cable 1A shown in FIG. 1, prevents excessive current oscillations arising during discharge processes in an electrostatic coating plant.

(12) FIG. 4 shows another exemplary embodiment of a high voltage cable 1D according to the present disclosure, and therefore, to avoid repetition, reference is made to the above description, with the similarly numbered reference signs being used for corresponding features.

(13) A distinct feature of this exemplary embodiment is that a shield 7D, which can be made of braided copper wire, is additionally arranged between the outer jacket 5D and the outer layer 4.2D of the insulating jacket.

(14) Finally, FIG. 5 schematically shows in an apparatus according to the disclosure for charging a coating agent, which apparatus comprises a high-voltage generator 8, which is connected via the high-voltage cable 1 according to the disclosure to an electrostatic atomizer 9, as known from the prior art.

(15) The electrostatic atomizer 9 emits a spray jet 10 of electrostatically charged coating agent (e.g. paint) onto an electrically grounded motor vehicle body component 11.

(16) The moderate electrical resistance of the high-voltage cable 1 advantageously prevents excessive current oscillations arising during discharge processes.

(17) The above-described constructions of the high-voltage cables 1C, 1D provide that permeating petroleum jelly does not modify or even result in a drop in the electrical conductivity of the high-voltage cables 1C, 1D.

(18) The disclosure is not restricted to the exemplary embodiments described above. Numerous variants and variations are possible according to the principles of the present disclosure. Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the disclosure should be determined, not with reference to the above description, but should instead be determined with reference to claims appended hereto and/or included in a non provisional patent application based hereon, along with the full scope of equivalents to which such claims are entitled.

(19) It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the disclosed subject matter is capable of modification and variation.