Thermal Analysis of Forced Cooled Cables

This paper presents a method for the heat transfer analysis of a circulating oil cooled cable system with emphasis on evaluation of the heat transfer mechanism between the circulating oil and the cable components. Based on a review of the iiterature the conclusion was that there is a lack of available test data which can be directly applied to this specific case. It was determined that the oil film heat transfer mechanism is a combination of forced and free convection. Evaluating these two individually and treating them as separate resistances in parallel leads to the conclusion that if the oil flow is laminar the forced convection resistance is mnuch greater than the free convection resistance. Thus conservative forced cooled ratings can be obtained by-neglecting forced convection and calculating oil film resistances based on free convection only.