DEVELOPMENT OF NEW LOW LIFT SNOW-RETARDANT INSULATED WIRE FOR OVERHEAD DISTRIBUTION LINE

Recently in the snowfall area - northern part of Japan, the snow-retar dant insulated wire with two fins structure is mainly used for 600 V a nd 6.6 kV class overhead distribution lines against snow damage. These two fins are placed longitudinally on the insulation at an angle 180- degrees and these height and width are relatively small. These values are 1 mm, 1.5 mm respectively. Although the snow-retardant insulated w ire has good performance against snow damage, the violent vibration of the snow-retardant insulated wire was observed several times under a strong wind and the fatigue of conductor occurred resulting from the r epeated high stress vibration at the wire supporting part. Therefore s ome theoretical aerodynamic analyses were conducted by various wind tu nnel tests with computerized simulations in order to make the vibratio n mechanism clear. From those analyses, it became clear that the leewa rd snow-retardant insulated wire were aerodynamically unstable and the vibration occurred with the influence of the wind induced, on windwar d snow-retardant insulated wire under certain condition related to som e leeward wire fin's angle, against a wind direction and sag differenc e of both wires. And also the measures against the above mentioned wer e investigated and the new type low lift snow-retardant insulated wire ; with spiral two fins was developed for the overhead distribution lin es. In this paper the aerodynamic vibration occurrence mechanism for t he snow-retardant insulated wire and the measures for the vibration su pression are mainly discussed.