Abstract

In a system for communicating information over a power line network, connection of power loads is interrupted in the vicinity of zero crossings of the A.C. power line waveform to provide a high impedance condition during which the transmitters and receivers of the power line communication carrier system can be efficiently coupled to power network transformer secondary windings in order to improve communications reliability. The communications apparatus is coupled to the secondary winding through a capacitance, chosen to substantially series-resinate the leakage inductance presented by transformer secondary winding. Each load is connected through an interruption device to the secondary winding, with the interruption device interrupting the flow of current from the secondary winding to the associated load, responsive to both detection of each zero crossing of a power distribution network voltage waveform and to the presence of the power line carrier communications signal.