Thermal characteristics of energized shielded and reeled trailing cables

The relationship between current load and temperature rise in shielded and reeled coal mine trailing cables was investigated. Temperatures within and on the cables were measured with thermocouples and the data recorded over time by computer. Steady-state DC load tests with two types of SHD-GC cable revealed that only 3 to 7% more current than Insulated Cable Engineers Association (ICEA) ratings for shielded cables was required to reach rated insulation temperature. The ability of the metallic shielding to dissipate heat was reflected in longer thermal time constants than for unshielded designs. Steady-state temperature rises where then monitored in a two-conductor unshielded, flat cable wound on a shuttle car cable reel. Stabilized axial temperature profiles exhibited maxima midway between the reel flanges. Static derating factors were considerably less than ICEA ratings for reeled cables. The finding suggest that deratings for trailing cables wound on reels should be based on the specific cable configuration.<
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