Double Wire Armour (DWA): Why Type 8 11kV Cables Require Dual Armor for Vertical Mine Shaft Suspension
When a heavy high-voltage cable is suspended vertically in a deep mine shaft (depths ranging from 500 to 2,000+ meters), it experiences mechanical stresses fundamentally different from horizontal installation. The single most critical issue is torsional stress from the cable’s own weight acting upon the helical armor structure.
当沉重的高压电缆垂直悬挂在深矿井中(深度范围从500到2,000多米)时，它经历的机械应力与水平安装根本不同。最关键的单一问题是电缆自身重量作用在螺旋铠装结构上产生的扭转应力。
The Single-Wire Armor Problem: A standard SWA (single-wire armour) cable features a helical layer of galvanized steel wires wound around the insulation in one direction (typically right-hand helix). When the cable hangs vertically and experiences the entire weight of its length below it, the helical geometry creates a mechanical disadvantage. The steel wire winding naturally wants to “unwind” or rotate under the extreme tensile load, generating enormous torsional stress throughout the cable.
