Elevated temperature operation of XLPE distribution cable system

The authors report on a continuing investigation to determine the maximum emergency and continuous ratings which cross-linked-polyethylene (XLPE)-insulated concentric neutral cables may sustain without impairing operating life. Detailed investigations include the measurement of temperatures at different parts of a cable during heavy current cycling and the resulting mechanical stresses and strains. The reasons for these mechanical forces are explained by considering the differential thermal expansion of the materials used in the cable. It is shown that thermally induced torques leading to mechanical failure may be influenced by neutral design. Core temperatures of 90 degrees or 110 degrees C appear to represent wise choices for operating temperatures.<
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