The application of real-time monitoring and rating to HPOF pipe cable systems

The Boston Edison Company has installed real-time monitoring and rating equipment on two independent pairs of 115 kV HPOF (high-pressure oil-filled) pipe-type cables. The real-time systems are remotely located at cable terminal locations so that critical data inputs can be hard-wired to the computing processor. Real-time information is made available via analog SCADA (supervisory control and data acquisition) connections and also by IBM PCs equipped with modems, which can call the remote systems to view real-time conditions or unload historical data. A PC software package complements the real-time system and gives planners, system operators, and cable engineers the ability to simulate cable system operation in an offline environment. In general, the identification of effective earth parameters in real-time is shown to result in increased emergency and normal ratings by replacing the conservative assumptions that must be made at the design stage with accurate real-time data. Lightly loaded circuits have exhibited large increases in short-time emergency ratings, as they normally operate at relatively low temperatures