Heat dissipation studies on sub- sea cables wound on winches

There are few applications in the industry where the power is conveyed to the destination by long cables which are stored on the winch rather being laid. This is particularly true if the load is a mobile system and cable length between the source and destination is of variable length as in the case of Remotely Operable Vehicles (ROV) and Underwater Mining Machines. This paper presents the dynamic analysis of heat transfer characteristics on subsea umbilical cable when wound on winches. Two different subsea umbilical cables were modeled and analyzed using Finite Element Analysis(FEA)Electromagnetic field simulation software with thermal analysis built-in. Asimulation results was compared with the experimental value and found to be matching with the simulation results. The paper determines the de-rating factor of the reeled subsea umbilical cable to supply power to the underwater system continuously without damaging the Subsea umbilical cable. Existing Insulated Cable Engineering Association (ICEA) do not provide de-rating factor for more than 4 layers and moreover the same is not suitable for subsea umbilical cables. The paper brings out the temperature rise in the subsea umbilical cable under wound and unwound conditions on a winch with multiple layers. The temperature rise at different layers of cable is arrived and this study will enable to size the cable suitably and control the amount of electrical loading that can be done over a period of time. FEA analysis was been done for 10 layers when it is in wound condition. From the results of the studies, safe ampacity curve for different layers of the cable is arrived for a specific ambient temperature. The safe ampacity curve can be used to estimate the operating window for the Underwater Mining Machine. The operating window for the mining machine can be improved by incorporating a suitable cooling mechanism on the cable winch.