Can 35kV cable shielding use two layers of copper tape instead of copper wire?
The shielding layer primarily protects against external electromagnetic interference, preventing the electromagnetic field generated by itself from interfering with the surrounding environment and conducting fault currents during operation.
Depending on the shielding performance requirements of the application, the materials used vary, including copper wire braided shielding, copper tape wrapped shielding, copper wire sparsely wound shielding, aluminum alloy wire braided shielding, copper-clad aluminum wire braided shielding, and aluminum-plastic composite tape wrapped shielding. To ensure shield continuity and reduce transfer impedance, copper tape and aluminum-plastic composite tape wraps typically require one or more annealed copper wires to be placed longitudinally within the shield layer as current drains. Shielding performance is often measured by measuring the suppression coefficient (R) of the shield layer. Copper wire braided shielding has R = 0.07 > Copper tape wrapped shielding has R = 0.02 > Copper wire sparsely wound (with reverse tie) has R = 0.01.
The primary current flow direction in copper tape shielding is the same spiral as in copper tape! Using copper wire shielding shortens the current path and generates less heat! Using two layers of copper tape for shielding increases the shielding cross-sectional area, reduces current flow, and reduces heat generation, both of which also provide signal shielding. However, given the high current carrying capacity of 500mm², the electromagnetic field generated by it is also large. When the short-circuit current exceeds a certain value, the effective cross-sectional area of two layers of 0.12mm copper tape cannot reach the larger effective cross-sectional area achieved by sparse copper wire wrapping. Based on the above considerations, sparse copper wire wrapping (with reverse tie wire) is far more effective than other shielding methods and offers more reliable continuity, so sparse copper wire wrapping is the preferred method for shielding.
