A: (1) wire is circular, such as the adjacent layer to the stranded when using the same cutter, easy to produce single-layer embedded within the outer layer to go, thus undermining the integrity of the circular structure. (2) When the wire under tension, the layers of torque generated by contrast, can be offset, to prevent the single layers in the same direction of rotation caused by loose stock, but can also avoid the wire in circular motion is not generated when the phenomenon of tension . (3) in the steel core, you can reduce the impedance to reduce the corona phenomena and power loss.