Cable Shield and Armour Protection Layers

Cables are comprised of several layers, each vital for performance, safety, and durability. Here, we introduce the conductor shield, insulation shield, metallic shield, and armour layer.

Conductor Shield Layer

This non-metallic layer is extruded directly onto the cable conductor. It primarily functions to smooth the conductor surface, eliminate sharp points (tip discharge), prevent air gaps between the conductor and insulation, and improve the electric field distribution. For XLPE cables, it also helps suppress electrical treeing and provides thermal shielding.

Insulation Shield Layer

The insulation shield is a semi-conductive, cross-linked material extruded over the cable's main insulation. Its key roles are to ensure intimate contact between the main insulation and the metallic ground shield, eliminate air gaps, and improve the electric field distribution around the insulation surface.

Metallic Shield Layer

Wrapped outside the insulation shield (typically copper tape or wire), the metallic shield is crucial for safety. It confines the electric field within the cable, protects personnel from electrical hazards, and acts as a grounded barrier against external interference. Importantly, it provides a path for short-circuit current during faults; for a 10kV system, a minimum area of 25 square millimeters is generally recommended.

Armour Layer

Usually a double layer of galvanized steel tape wrapped over an inner sheath, the armour layer offers vital mechanical protection against external damage during installation and operation. It also provides additional grounding protection. Other variations exist, like steel wire or non-metallic armour, for specialized cables.

If you need any shield cables and armored cables, please contact me via email  sales@tindepowercable.com