surface mining electrical cable

Type SHD-GC 3/C #1 AWG 8kV trailing cable is approximately 0.410 Ohms/km at 20°C reference temperature for a single conductor, calculated from the copper’s material resistivity combined with the #1 AWG conductor cross-section (approximately 42.4 mm² or 53,486 circular mils). This resistance value increases to approximately 0.495 Ohms/km at 90°C operating temperature due to copper’s positive temperature coefficient of resistance. For a complete three-phase circuit using this cable type, the total circuit resistance including all three phase conductors but excluding the ground return path is approximately 0.410 Ohms/km at 20°C or 0.495 Ohms/km at 90°C. When operating a mine shovel or dragline drawing 150–160 amperes over a typical 1,000-meter (1 km) cable run from the mine substation to the equipment, the three-phase voltage drop across this cable is approximately 55–70 volts at the reference condition, representing a drop of roughly 0.75–1.0% from the 8,000-volt nominal supply. This voltage drop magnitude is acceptable for most mining equipment applications and remains within typical power system design standards that permit up to 2–3% voltage drop on secondary feeder circuits. The physical mechanism behind this resistance is the collision of free electrons within the copper lattice structure, where random thermal motion of atoms creates an effective “friction” that opposes electron flow, converting electrical energy into heat at a rate proportional to I²R.