Abstract
The offshore wind industry is becoming an ever more important player in the power generation scene, with a constant rise of the installed power and an even more marked growth of the number of proposed projects. The layup configuration usually adopted for inter-array cables stranding is the unilay, but another possible configuration is the SZ lay-up, in which the lay-up direction is changed regularly from right-hand (Z) to left-hand (S) and vice versa. Compared to the unilay stranding machine, a SZ stranding machine is a cost-effective alternative in terms of CAPEX. However, the alternating laying direction increases the complexity of the cable structure, causing its modelling and understanding to become a more challenging task. The experience collected by the industry on unilay cable during handling, installation and operation may not be directly transferred due to the peculiarities of the SZ lay-up. A combined bending and axial compression test was performed on a SZ stranded, three-core 66 kV inter-array cable, with 800 mm² XLPE insulated copper conductors to investigate its mechanical performance under such load. A core factory joint and one lay-up inversion section were part of the sample under testing. The cable was subjected to bending cycles with controlled curvature under constant axial compression in air at room temperature. Axial load, twisting, bending moments and curvature were continuously monitored. After 200 cycles, the test was concluded without visual sign of damages or buckling. No abnormalities were observed in the data collected by the instrumentation, with constant twist range, stable bending moment and maximum curvature. Ultimately, the sample was dissected, and no damage was observed on the cable elements and on the factory joint