Radio Influence Voltages Caused by Surface Imperfections on Single and Bundle Conductors

1. A test setup has been constructed for obtaining RI generation characteristics of conductors for extra-HV transmission lines. 2. Point protrusions lower the noise. starting voltage of energized conductors. With metal and wet dielectric points the reduction is larger for longer points. For dry dielectric points the reverse seems to be true. 3. Relatively long point protrusions on conductor surface may cause a sudden jump of RIV as the conductor voltage passes a critical voltage, which varies with the height of the point. 4. The height of a point protrusion determines the per-cent reduction of the noise-starting voltage regardless of the conductor diameters. 5. When a conductor with point protrusions is stressed at a given per cent of its ideal noise-starting voltage (i.e., smooth surface), a higher RIV will result for a larger ratio of the point height to the conductor diameter. 6. The coronaand RI-starting gradient for a given point imperfection on 1-, 2-, 3-and 4-conductor bundles is the same no matter where it is located, but the RI generated is not the same: it is lower for the points facing the center of the bundle. 7. The RI generated from a given point imperfection depends not only on the conductor surface gradient but also on the gradient distribution both radially outward from the surface and around the conductor. 8.