Life Evaluation of a 35-kV Submarine Power Cable in a Continuously Flexing Environment

Abstract

JPT Forum articles are limited to 1,500 words (including 250 per table or figure) or a maximum of two pages. Forum articles may present preliminary results or conclusions from continuing investigations or may impart general technical information that does not require publication as a full-length paper. Forum articles are subject to approval by an editorial committee. paper. Forum articles are subject to approval by an editorial committee. Letters to the editor are published as Dialogue and may cover technical or nontechnical topics. SPE-AIME reserves the right to edit letters for style and content. Introduction This paper evaluates the life of a 35-kV power cable for connecting a single-anchor leg mooring (SALM) buoy with a deepwater, offshore platform. This system is unique in that the cable flexes constantly during compression as the mooring buoy moves in the water. To predict the effects of this constant flexure while energized, a flex simulator and electrical circuit were devised to duplicate the service environment as closely as possible. System Description A deepwater platform is connected by power cable to a SALM buoy a few asks away. The buoy design (Fig. 1) includes an articulated leg with universal joints to which the cable is clamped. Flexing of the loop in the cable where it crosses a universal joint was our major concern. The cable must operate continuously at 34.5 kV for an expected life of 30 years. Test Cable and Apparatus Description A three-conductor cable nearly identical to the production cable was manufactured for the evaluation. It production cable was manufactured for the evaluation. It consisted of three No. 1/0 AWG stranded copper conductors with an extruded ethylene-propylene rubber (EPR) insulation, These conductors were cabled together and armored with 30 No. 4 BWG galvanized steel wires, each jacketed with high-density polyethylene. The test apparatus consisted of a fixed cable support at one end and a pivoting swing-ann 18 ft (5.49 m) away powered by a hydraulic piston (Fig. 2). The swing-arm pivoted at the fixed base and was raised and lowered at the free end in a sinusoidal motion by a hydraulic piston. The test cable was clamped to the fixed support and the swing-arm, with a loop of the desired size in between. JPT P. 914