A Method of Analysing Quarter-Wave Filters on Multiphase Power Transmission Lines

Quarter-wave HF filters were originally developed and studied on a single-conductor test line in Japan.1 Subsequently, the filters were installed on a 250-kV, three-phase line and the field results were found very satisfactory. In the present paper an exact general analysis of quarter-wave filters on multiphase lines is developed. The application of this analysis to the single-conductor test lines1 shows a very good agreement between the calculated and measured results. Equations for lines with bundled phase conductors are also derived. It is found that the performance of practical filters on bundled-conductor lines deteriorates with the increase of the equivalent radius of the bundle.