Abstract: In a multi-wire electric power cable, particularly a supply cable for borehole units such as pumps, each insulated wire is protected by a corrugated sheath. In order to be able to withstand high pressures of, for instance, 300 bar, the corrugation of the corrugated sheaths is so developed with respect to depth and pitch of corrugation that the length of each corrugated sheath is between 33 and 67%, and preferably 45 to 55%, shorter than the smooth tube from which it has been produced.

Abstract: A composite corrugated electrical cable is provided in accordance with the teachings of the instant invention wherein a plurality of corrugated tubular conductors are concentrically positioned with respect to each other, each of such tubular conductors having corrugations that differ from those of the immediately adjacent tubular conductors in wave pitch, shape, depth or longitudinal separation. The corrugation arrangements permit differential longitudinal displacement between adjacent tubular conductors for achieving a composite cable of high flexibility. Further, various corrugation protrusions engage the adjacent tubular conductors to provide radial spacial separations between the adjacent tubular conductors thus providing an intermediate path through which a cooling medium may be passed for increasing the heat dissipation and the power capacity of the electrical cable.

Abstract: There is disclosed a process and apparatus for manufacturing flexible, shielded coaxial cable exhibiting improved magnetical screening capabilities wherein a tubular outer conductor is concentrically formed about an inner conductor with spacer means being disposed in the annulus between conductors. Accordingly, about the inner conductor including spacer means therefore, there is formed an inner component tube of a conductive material by the continuous forming in a lengthwise direction of a metal band into a tube having longitudinal edges welded together in a continuous, longitudinal welded joint. Concurrently, at least one further component tube is formed concentrically about the inner component tube by the lengthwise deformation of a second metal band of a ferromagnetic material into a second tube having opposed longitudinal edges which are also welded in a longitudinal direction in a continuous, longitudinal welded joint.