THE IMPACT OF CURRENT LOAD ON MINE-TRAILING CABLE THERMAL LIFE

The U.S. Bureau of Mines has determined a method for calculating coal mine portable power cable thermal life for a specified temperature loa ding. This work was the culmination of a multifaceted research project involving 1) accelerated life tests of insulation and jacket material s and 2) steady-state and cyclical loading of cables. Composite Arrhen ius curves were derived for common insulation and jacket materials to identify the key cable quality that precipitates thermal failure. Plot s of temperature rise versus current for popular cable sizes were then referenced to develop a correspondence between cable life based on th ermal degradation and current loading. Predictions of cable thermal li fe were made through integration over variable load cycles and, conseq uently, variable operating temperatures. This procedure may have utili ty for both the U.S. Mine Safety and Health Administration (MSHA) and mining machine designers in determining the appropriate cable size for new equipment.