Thermal Characteristics of Energized Coal Mine Trailing Cables.
Proc the 9th WVU Int'l Mining Electrotechnology Conf 1988 :8 pages
The U.S. Bureau of Mines conducted research to determine the relationship between current load and temperature rises in coal mine trailing cables. Six low-voltage, unshielded, portable power cables were continuously and intermittently loaded with direct current of various magnitudes. Temperature rises within and on the cables were measured with thermocouples, and the data were recorded with a computer. Thermal time constants were calculated and fixed the periods of the duty cycle tests. Relationships between average temperature at the conductor-insulation interface and current load were established. The steady state and intermittent currents that produce a 90 deg. C average conductor-insulation temperature were then determined by mathematical modeling. Comparisons to Insulated Cable Engineers Association steady state ratings revealed that 10 to 25 pct more current is required to reach rated insulation temperature. Examination of the maximum intermittent temperatures attained showed that autoignition of coal dust and burns to personnel handling the cable would not be concerns if the temperature at the conductor-insulation interface averaged 90 deg. C.
Proc. the 9th WVU Int'l Mining Electrotechnology Conf., 1988, PP. 178-185