A new carrier-current coupling capacitor

By means of coupling capacitors connected to high voltage power transmission lines, high frequency carrier currents in different frequency channels may be transmitted over the power lines for supplementary services such as relaying, control, and communication. A new design of coupling capacitor has been made which, by combining 1, 2, 3, or 4 units in series, may be used on 69, 138, 230, or 287 kv circuits. Capacitors of the latter rating are being used on the Boulder Dam line of the city of Los Angeles.