Specifications

PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Book 131
Figure 4.12 Power Distribution Model
Attenuation is most easily understood in terms of a voltage-divider circuit formed by the output impedance of the
transmitter, the impedance of the various mains circuit branches, and any loads present on the mains branch circuits. At
the communication frequencies of the PL Smart Transceiver (70kHz to 138kHz), the significant impedances are due to
the series inductance of the mains wiring itself, capacitive loads between line and neutral, resistive loads between line
and neutral, and the coupling between L101 and L102 which occurs due to mutual inductance and parasitic capacitance
between phases. If these distributed impedances are lumped together and treated as if a single frequency is being
transmitted, a simple attenuation model results as shown in Figure 4.13.
Figure 4.13 Power Mains Attenuation Model
This model illustrates that minimizing the series impedances and maximizing the line-to-return path impedances reduces
the attenuation of the transmitted signal.