摘要:
A cable for use in a predetermined voltage class, has a conductor; an insulating layer surrounding the conductor, the insulating layer having a thickness selected to provide a predetermined electrical stress when the cable is operated at a nominal voltage in said predetermined voltage class; and a protective element around the conductor having a thickness and mechanical properties selected to provide a predetermined impact resistance capability, the protective element having at least one expanded polymeric layer. The insulating layer thickness and the protective element thickness are selected in combination to minimize the overall cable weight while preventing a detectable insulating layer damage upon impact of 50 J energy. A method for designing a cable is also disclosed.
摘要:
The present invention is directed to a hybrid electrical cable providing for power transmission or distribution and data and/or voice signal communications. In one preferred embodiment, the hybrid electrical cable includes a power cable having a group of one or more high voltage power conductors for conducting power and one or more groups of low power signal conductors for transmitting voice and/or data and/or control signals. The cable further includes a power cable insulation jacket overlying the group of one or more power conductors. The power cable insulation jacket includes a soft magnetic material, preferably a soft ferrite magnetic material, for RF absorption. The cable additionally includes an outer grounded metallic jacket or sheath overlying the power cable, the power cable insulation jacket and the one or more groups of low power conductors.
摘要:
An electric power cable line is arranged in which the insulating layer is increased to a greater thickness at two end portions of each cable than a thickness at the other or center portion of the same. Since the insulating layer is increased in thickness at the end portions of the cable, thus an electrical stress exerted on the overall layer construction of the end portions is lowered. Hence, the dielectric strength of the end portions of the cable becomes high and the power cable line will thus be increased in the operational reliability.
摘要:
A cable core, comprising conductors with insulation and carrying a conductive shield layer is protected and shielded by a corrugated metal tube cooperating either with individual, electrically conductive sealing rings, or a conductive helical sealing ribbon with foam filling any gaps. The construction ensures adequate space for thermal expansion of the insulation without undue tensioning of the tube. A method of making the assembly is described and examples for the ribbon and the foam are given.
摘要:
This invention is an improved filling compound for preventing moisture penetration along the interior of high voltage electric power cables. Amorphous polypropylene, mixed with carbon where it must be semiconductive, is an extremely good filling compound because of its electrical characteristics and also because of its good flow characteristics when extruding. When the cable is to be used under conditions where it must withstand temperatures so low that the polypropylene becomes brittle, it can be blended with polyisobutylene rubber to withstand lower temperatures, but the blend must be kept within limits to prevent loss of the good flow characteristics of the amorphous polypropylene.
摘要:
A system for the underground distribution of electrical power is provided and includes an electrical cable construction particularly adapted for use underground; and, the cable construction has a central conductor, a tubular insulator system for the conductor, a dual-purpose sacrificial anode supported by the insulator system and extending along substantially the full length of such insulator system, and a concentric neutral conductor supported by the insulator system and engaging the anode at a plurality of points therealong, with the dual-purpose sacrificial anode protecting the concentric neutral conductor against galvanic and soil corrosion as well as reducing AC corrosion of the concentric neutral conductor by providing additional surface area for the dissipation of currents leaving the neutral conductor.
摘要:
A cable for transmitting electrical power incorporating a shield serving as a low resistance return path to carry heavy fault current. The shield comprises a multiplicity of helically wound elongate metallic elements such as straps, tapes or wires. The lay length of the metallic elements, if tapes or straps, is selected such that thermal expansion and elastic stretch of the straps or tapes is sufficient to accommodate expansion and contraction of the insulator within the elastic limit of the metallic elements. The lay length of the metallic elements, if wires, is selected such that the thermal expansion of the wires is sufficient to accommodate expansion and contraction of the insulator without elastically stretching the wires.
摘要:
In an electrical distribution cable comprising a number of insulated electric power conductors and a neutral conductor, the assembly of conductors being enclosed in a protective insulating sheath, a coaxial connector is permanently secured to the cable at each of a plurality of spaced locations along its length before it is installed. The inner conductive element of each connector is electrically connected to one of the power conductors of the cable and the outer conductive element of the connector is electrically connected to the neutral conductor of the cable. Each of the coaxial connectors is at least partially embedded in a protective insulating covering integral with or bonded to the protective sheath of the cable. The neutral conductor may be laid up helically with or parallel to the power conductors or it may be in the form of an outer concentric conductor.
摘要:
An electric high-voltage compressed-gas-insulated power transmission line has an electric power conductor within and in spaced relation to a tubular enclosure filled with compressed gas insulation and able to withstand normal stressing electrically and/or thermally but not able to withstand such stressing when it becomes excessive. At least one electrically grounded electric conductor is fixed to the inside of this enclosure and extends longitudinally thereof and is itself capable of withstanding such excessive stressing. This grounded conductor projects transversely from the enclosure''s inside far enough to cause the electrostatic field normally surrounding the power conductor to concentrate on the grounded conductor so the latter receives such stressing instead of the enclosure, thus protecting the enclosure.