Abstract
Galloping is occasionally observed in overhead transmission lines owing to ice accretion. Galloping characteristics and effects of countermeasures against it might vary depending on the ice accretion type, namely, freezing rain, wet snow accretion, and in-cloud icing, because the shape of ice accretions can vary based on the type. In Japan, galloping is often caused by wet snow accretion in plain areas. To investigate the galloping effect on overhead transmission lines owing to wet snow accretion, field observations of four-bundled conductors have been carried out at the Kushiro test line since 2014. On January 12, 2022, large galloping was finally observed at this site. The conductors mainly vibrated in the vertical two-loops/span mode coupled with the horizontal and torsional modes, where the maximum total amplitude reached approximately 5.8 m in the vertical direction. Contrarily, in the line that was installed loose spacers as a countermeasure, the galloping amplitude was significantly reduced compared with that observed in the line with normal spacers.
