Modeling Sudden Ice Shedding From Conductor Bundles
Sudden ice shedding from conductor bundles was modeled numerically and experimentally by improving the approaches proposed formerly for a single cable. The experimental study was carried out on a small-scale laboratory model of one span of a twin bundle. A numerical model of the experimental setup was developed using the commercial finite-element software ADINA. This model was validated by simulating: 1) the vertical cable vibration during former load shedding tests on a full-scale line of single conductors; 2) the bundle rotation on a full-scale twin bundle during former static torsional tests; and 3) the vertical cable vibration and bundle rotation at midspan during the present load shedding tests on a small-scale twin bundle. The coincidence of calculated and measured tendencies justified the applicability of the numerical model to simulate the vibration following ice shedding from bundled conductors in most cases. The model was finally applied to simulate sudden ice shedding from a full-scale span with a twin bundle. Simulation results showed that the application of spacers reduces the cable jump height during this vibration; however, a higher number of spacers in the same span does not decrease the angle of bundle rotation.
Dynamic Behavior of Cable Systems with Spacers Following Ice Shedding
Ice accretion on cables of overhead transmission lines is a serious and frequently arising problem in cold regions. The accreted ice leads to heavy static load, while ice-shedding may result in high-amplitude vibrations which are usually associated with excessive transient dynamic forces. A widely used method to attenuate the vibration due to wind or ice-shedding, and reduce the resulting transient dynamic forces is the application of spacers between two, three or four conductors. 
 
The dynamic behavior of systems of two, three and four conductors with spacers following ice-shedding from one subconductor is examined in the present study. Modal analysis is carried out, which calculates the first few natural frequencies and provides the damping performance of the system. Results are compared with those obtained for a single cable and for a system of two cables with a cross-tie which is often applied in cable-stayed bridges. A numerical model is also constructed using the finite element method. Simulations with the constructed model show how the resistance of cable systems against vibrations following ice-shedding increases with the application of spacers.
Dynamic analysis of overhead cable vibrations as a result of ice shedding
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