Abstract :
CARRIER-CURRENT equipment is being employed for three distinct services on the Boulder Dam transmission line: first, for pilot channels for automatic protective line relays; second, for a transmission channel for supervisory control equipment which provides control from Boulder power plant of the two switching stations between Boulder and Los Angeles; and third, for telephone communication between Los Angeles, Boulder, and the two intermediate stations, and to transmit orders to line patrolmen who may be working at any point along the line. These three functions may be performed simultaneously without interference with each other, and are not affected by power conditions or normal switching conditions on the line.
