Shieldwire
Structure
Shieldwire is similar in appearance to ACSR conductors and has a structure consisting of 7, 19, 37 strands of galvanized steel wire of classes B, A and C or AW steel wire, which are woven concentrically around one of the wires.
In shieldwires, the winding direction of the wires in the outer layer is left-handed.
Application
Shield wires or protective wires or guards are used in overhead power transmission lines.
Shield wires are placed at the highest point of the mast in order to minimize the possibility of lightning striking the phase conductors carrying electric current and short-circuit currents, and through the masts, they transfer short-circuit currents to the ground and practically earth.
Two shield wires can be used in high voltage (HV) lines.
In power transmission lines, OPGW cable can be used to perform the role of shield wire in addition to telecommunication communication due to the presence of optical fibers in its structure.
In medium voltage distribution lines, shield wires are installed under the phase conductors.
Features
earthing lightning currents and short circuiting through high voltage power towers
high mechanical strength and low diameter due to better tolerance of forces from ice and wind
Reference standards
Shieldwires are produced according to the requirements of ASTM B415, ASTM B416, ASTM B498 standards.