Development of galloping endurance design for extra large 6-conductor bundle spacers by the experience of the full scale 500 kV test line

Large diameter bundle conductors, which result in lower line inductance is one of the most cost effective methods to gain stable power transfer capability on a long bulk power transmission line. To bring this new type of conductor into practice, since galloping is a major cause of damage to transmission lines in certain regions of Japan, it is essential to grasp the dynamic mechanical loads during the phenomena. New methods for designing several kinds of hardware involved in the new 500 kV bulk transmission facilities utilizing extra large 6 conductor bundles were developed using three years of field experience on a full scale 500 kV testing line. The 769 m test line supported by three full scale supporting structures were constructed on Mt Sanpo (alt 970 m) located 35 km from the Japan sea, where frequent galloping phenomenon was observed. This paper features the methods used in designing the spacers developed from the field studies