Multichannel Carrier-Current Facilities for a Power Line

A carrier-current system providing a relatively large number of channels is in service on a high-voltage power line. The facilities provide: 1. Transmission of signals both ways for the opening of the circuit breakers at the remote end by the operation of relays at the near end. 2. Two-way telephone service between any extension telephone at the remote generating station and any telephone connecting to the main telephone switchboard in the central office building. 3. Two-way telemetering (station generation one way and system total generation the other way). 4. Transmission from the system operator's office to the station of automatically generated load-control signals used to increase or decrease automatically the station generation. 5. Two channels in each direction for future requirements. This paper describes the methods employed to obtain these channels over a single power line, including the special precautions taken with the high-speed transferred trip signals to prevent faulty tripping of the line due to external disturbances which might generate carrier-current tripping pulses.