Vibration of High Voltage Conductors Induced by Corona from Water Drops or Hanging Metal Points

Corona-induced vibration was studied in experimental set-ups consisting of a single smooth conductor placed on the axis of a cylindrical mesh cage. Under artificial rain the beam type of vibration, i.e. whe, re the conductor is simply supported at two ends by the insulators, was used. Amplitude of the vibration of the conductor and corona current were Tmeasured under rain and during the drying period, i.e. after stopping the spray. The above studies were repeated when water was allowed to fall at a single location on the conductor. The acceleration of the ejected droplets from the hanging drops was measured with a high speed camera. When the hanging water drops were replaced by conical metal points, a mass-spring configuration was used. The displacement of the conductor under dc and 60Hz applied voltages was measured. On the other hand, when an impulse voltage with a repetition rate equal to the natural frequency of the system was applied to the conductor, the vibration was similar to that observed under rain. The amplitude of the vibration and the corona current were measured as-a funetion of the number of the metal points, and the corona-indticed force was estimated. It is concluded that the actual electric field at the tips of the hanging drops is much smaller than the applied field and the intermittent presence of the space charge around the hanging drops is the main cause of the vibration.