Radio frequency signal transmission on medium voltage power distribution lines

A series of tests measuring HF signal attenuation were performed on a de-energized 15 kV three-phase power distribution feeder. The feeder consisted of a U-shaped line measuring approximately 208 m in length with varying line geometry around the circuit. RF signals in the range of 2 to 30 MHz were injected in one phase of the feeder and the propagated responses were measured at two locations along the feeder. Tests were conducted with and without shunt power equipment (distribution transformers, arresters and capacitors) connected to the feeder. The characteristic line impedance of different line geometries was calculated by analytical means and found to be consistent with experimental results. Attenuation and characteristic impedance were found to be relatively constant at frequencies between 15 and 30 MHz with minimal influence from line geometry and power equipment placement.