On the Limits of Applicability of the Theory of String Vibrations in Assessing the Configuration of Wires of a Power Transmission Line in the Process of One-half-wave «Dance»

Abstract

When studying the «dance», some authors assume that the configuration (shape) of the wire during a onehalf-wave dance corresponds to a sinusoid and the sinusoidal law is used as a coordinate function. With such fluctuations, all sections of the wire within the half-waves have the same direction of movement, simultaneously pass the neutral position and reach the extreme upper and lower positions. However, observations of the oscillatory processes of wires on the anchor spans of a power transmission line showed that at low mechanical stresses of the wire, the nature of the oscillation with one half-wave differs significantly from the above. The difference lies in the fact that additional vibration nodes appear within the span. Between the nodes, the wires move in antiphase, resembling three-half-wave oscillations, only with different half-wave lengths (edge effects). The coordinates of the moving nodes, as observations show, depend on the initial mechanical stress of the wire. In this regard, the question arises about the limits of applicability of the theory of string vibrations in describing the configuration of wires in the process of a one-half-wave dance. The results of experimental data on the identification of wire configurations for single-half-wave oscillations are presented. The calculation formula for the critical voltage of the wire, at which edge effects are observed, is obtained. The relevant conclusions are presented at the end.