Approximate Predictions of Ice Accretion on an Overhead Transmission Line which Rotates with Constant Angular Velocity

An airflow carrying either freezing-fog droplets or wet snowimpinging on an overhead transmission line causes ice to accreteon the windward side of the conductor. In the vicinity of theconductor anchors (at the towers), axial growth, in the formof a spike of ice growing outward into the wind, is observed.Near the centre of the span this eccentric ice loading causesthe conductor to twist so that cylindrical-sleeve growth isobserved. For small-diameter conductors of low torsional stiffnessthe conductor rotation can amount to many complete revolutions.It is useful to obtain some understanding of this mode of iceaccretion prior to undertaking any investigation of the aeroelasticsystem under icing conditions and it has direct relevance toice loading on small-diameter conductors. To this end, a simple‘icing-clock’ model for sleeve growth in which theconductor rotates with constant angular velocity is proposed,enablinganalytical results on the mechanics of the ice evolution processto be obtained.