Snow Accretion on Electric Wires and its Prevention

Abstract

AbstractThis paper presents a study on the accretion of wet snowflakes transported by a strong cyclone on electric wires by means of wind-tunnel experiments and field observations with the aim of successfully preventing them from accreting on and causing damage to power lines and high-voltage power-transmission towers in snowy areas in such countries as Japan, Canada, and the U.S.A. Although extensive studies have been made on snow accretion in Japan since the 1930's by many workers, their studies have been restricted to the coastal regions of central Honshu facing the Sea of japan, which are typified by heavy wet snowfalls of the monsoon type in a weak wind of less than 3 m/s at a temperature between –1° and +1.5+C continuing throughout the day. However, it has long been known that a cyclone characterized by a strong wind exceeding 10 m/s that carries heavier and wetter snowflakes can cause snow accretion on electric wires to grow to 20–30 cm in diameter. Because its detailed accretion processes and mechanism had not been clarified, studies have been made on the growth processes of snow accretion, the adhesive stress of snow to a wire, the structure and texture of the accreted snow, coefficients of collision and collection of snow on the wire, and trajectories of individual snow particles impinging on or passing by a wire at various wind speeds. It has been confirmed that wet snow can accrete on wires at any wind speed between 0 and 20 m/s. Moreover, new techniques have been developed to prevent wet snow from accreting on wires, and these have proved to be effective in situ for any type of snow accretion in Hokkaido.