ELECTRICAL CABLE

An electrical cable (100) is provided. The cable has an electrically insulating outer jacket (101), and a number of phase conductors (102) arranged within the outer jacket (101). The phase conductors (102) extend along the longitudinal extension of the cable (100), and the phase conductors (102) are individually provided with an outer electrically insulating sheath (104). The phase conductors (102) are arranged within the outer jacket (101) such that a central space (105) is formed between the phase conductors (102), and an earth conductor (106) is arranged in the central space. The earth conductor has electrically conducting twinned strands.

DETAILED DESCRIPTION

InFIG. 1a cross sectional view along a transversal plane of an embodiment of an electric cable100according to the invention is disclosed. Thus, the electric cable100has a longitudinal extension. The electric cable100may be a power cable.

The electric cable100comprises an outer jacket101. The outer jacket101is of a water proof and electrically insulating material, such as a polymeric or rubber material. The jacket101may for example be comprised of polyethylene, or other suitable material with low cold flow. The outer jacket101extends along the length of the electrical cable, such that the interior of the cable100can be shielded off from the surrounding environment.

The jacket101may be extruded onto four phase conductors102of a suitable extrudable and electrically insulating material, such that the four phase conductors102are arranged within the jacket101. The four phase conductors102are sector shaped, with a blunted apex103. The four phase conductors102each comprise a plurality of compressed and twined strands, and extend along the longitudinal extension of the electrical cable100. The strands are of aluminum or copper. Peripherally of the compressed and twinned strands an insulating covering sheath104is arranged individually on each phase conductor102. The sheath104is made of an electrically insulating plastic material.

The blunted apex103of the phase conductors102provides four phase conductor sides along the transversal plane of the cable100; one side, being a circular arc side, facing outwardly towards the jacket101; two sides, being radial sides, facing neighboring phase conductors; and one side, being a blunted apex side, facing a central space105. Thus, the blunted apexes103of the four phase conductors102provide the central space105. Within the central space an earth conductor106is arranged. The earth conductor106comprises a plurality of compressed and twined strands and extends along the longitudinal extension of the electrical cable100. The strands are of aluminum or copper.

The arrangement of the earth conductor106centrally of the cable100provides a series of advantages. Firstly, the earth conductor106may be protected from damage by the peripherally arranged phase conductors102. In this way, the phase conductors102will damaged before the earth conductor106upon damage of the cable100. Hence, the damage to the cable100will be noticed by loss of current before the cable installation looses electrical isolation. Also, there is no need to collect the outer shield of earth conductors, according to the prior art, into one earth at the installation site. When the earth conductor106is centrally arranged, it is already collected in a way facilitating installation and avoiding complicated earth connection shoes etc.

The central earth conductor106may preferably be arranged without a peripheral insulating plastic material, such that the electrically conducting twinned strands of the earth conductor106contacts the sheath104of at least some of the phase conductors102. In this way, the twinned strands of the earth conductor106will provide an outer peripheral corrugated interaction surface107. The corrugated interaction surface107will be electrically insulated by the sheaths104of the phase conductors102, while simultaneously increasing the interaction surface between the earth conductor106and the adjacent phase conductors102, due to the corrugation thereof. This arrangement will improve the capability of the cable100to withstand longitudinal displacement of the conductors within the jacket, thus improving self supporting characteristics of the cable100. Since the earth conductor106already is twinned, it is easier and safer to install than a concentric earth conductor where the individual strands are spread around the phase conductors. Also, since the earth conductor106is arranged without a peripheral insulating plastic material, the risk of injuries, due to stripping action of the earth conductor during installation, is decreased.

Interstices between the phase conductors102and earth conductor106may be provided with filler threads (not shown).