Carrier-current losses measured and interference minimized on Boulder-Los Angeles transmission lines

Two unusual facts were disclosed during the field testing of the supervisory-control carrier-current channel on the 287-kv Boulder Dam-Los Angeles transmission lines. Carrier-current losses were much higher than calculations and previous experience had indicated. The interference from power equipment arcs could not be isolated by the use of resonant choke coils, requiring special circuit designs for satisfactory operation.