Abstract: A powerline carrier control installation includes a control transmitter with an audio frequency output voltage, an isolation transformer, a coupling capacitor for parallel coupling to an a-c voltage network, and a device for suppressing a line frequency backward voltage. For coupling the audio frequency output voltage to the a-c voltage network, a resonant circuit tuned to the audio frequency is provided, the resonant circuit capacitance being supplied by the coupling capacitor and the resonant circuit inductance formed essentially by the main field inductance of the isolation transformer, eliminating the need for a separate coupling choke.A device, specifically the powerline carrier control transmitter itself, is equipped to deliver, in addition to the audio frequency output voltage, a line frequency compensating a-c voltage which has a low amplitude in comparison to the line a-c voltage in order to suppress the line frequency feedback transmitted from the network.

Abstract: A powerline carrier control system having a carrier transmitter which delivers an audio-frequency output voltage, subdivided into transmitted pulses, to a power-line carrier control receiver via a coupling unit and the power distribution network. In order to reduce ringing (after-oscillation) of the coupling unit, an auxiliary decay circuit switches the AC voltage being transmitted into a phase shift or into phase opposition to offset the after-oscillation. In this manner, distortion of the transmitted information is largely avoided.

Abstract: In a powerline carrier control system, a powerline carrier control transmitter delivers an audio frequency voltage to the powerline carrier control receivers via a coupling unit and AC supply network. The coupling unit consists of a coupling transformer and an L-C combination which would normally insure that the network AC voltage is kept completely away from the powerline carrier control transmitter. In the system disclosed, back voltage is intentionally permitted and a supplementary AC voltage of line frequency is superimposed on the transmitter output voltage to buck the back voltage and thereby prevent current at the line frequency from the AC network from flowing through the transmitter. This simplifies and reduces the cost of the heretofore expensive components of the L-C combination.