Heavy salt deposition onto a distribution line by a seasonal wind in winter

Covered conductors and insulators installed in a 6.6 kV distribution line passing through a coastal area along the sea of Japan are heavily polluted with sea salt conveyed by a northwesterly seasonal wind in winter. To understand the practical situation of the deposition of sea salt in winter, salt deposit onto the covered conductor and pin insulators was measured along with the salt quantity in the air and the weather conditions. Small sea water particles began to fly above a wind velocity of 5 m/s. Continuous observation of the partial discharge occurring around a distribution transformer revealed that the partial discharge was prone to occur when the hourly mean wind velocity exceeded 8 m/s. Sea salt rapidly deposits onto the insulators or covered conductor during occurrence of sea water spray from a high wave above 3 m. The equivalent salt deposit density (ESDD) happened to reach 1 mg/cm/sup 2/ within several hours in this area.