LCL Characteristics of Parallel Transmission Line with Load Circuit

In Japan, a power-line communication (PLC or PLT) system was approved only as an in-house system. One of concerned matters is leakage electromagnetic fields from power lines, which are mainly caused by common-mode currents. The common-mode current should be estimated under a condition of LCL (Longitudinal Conversion Loss) of 16 dB in the Japanese rule. In this paper, the characteristics of LCL are discussed at an input terminal of two-parallel line, which is modeled after a simple inhouse power line, with unbalanced load circuit on a viewpoint of transmission-line theory. By applying an equivalent expression concerning common and differential modes at outlet terminals, the analysis is developed.