Ampacity Derating Analysis of Winch-Wound Power Cables: A Study Based on Deep-Water ROV Umbilical

This paper presents the electrothermal modeling and simulation done on a subsea standard 7000-m-long, Kevlar-armored, electro-optic umbilical (EOU) of the deep-water remotely operated vehicle (ROV) ROSUB 6000, to determine the ampacity derating factors (ADF) when used in winch-wound configurations. The ampacity derating analysis is done, using the finite element analysis (FEA) up to 23 layers, and the identified ADF could be applied to any standard subsea umbilical operated in multilayered configurations. It is identified that the 23-layered umbilical needs to be derated to 92% for continuous operation with direct current power supply, while increased loading reduces the operation window and needs a cooldown period of 182 h. In the case of operation with 6600 V and 400 Hz, the 23-layered umbilical operation window is 7.2 h, independent of the connected active load. The results serve as a guideline for determining the tradeoff among operating voltage, frequency, cable design, ADF, and the operational window for multilayered cable configurations.