Thermal modeling of portable power cables

The US Bureau of Mines investigated the performance of portable power cables under time-varying load conditions. This research had a twofold purpose: (1) to define the thermal characteristics of electrically overloaded trailing cables; and (2) to construct a thermal model for cables to predict cable temperature rises resulting from load currents. Several tasks were undertaken in support of these goals during the three-year research effort. Overload tests ranging from 2 to 12 times rated ampacity were conducted in the Pittsburgh Research Center's Mine Electrical Laboratory. A thermal model of energized type G-GC trailing cables was constructed based upon empirical data from the US Bureau of Mines load tests. This model was then incorporated into an interactive computer program that can assist designers and approvers of mining machines in selecting the appropriate size trailing cable. This program can be the basis for a cable protection system which ensures that cables are not the source of fires, ignitions, burns, or explosions underground.