Capacitive Power Tap-Off from Transmission Lines Using Ground Wires: Calculation of the Equivalent Circuit Parameters

The capacitive coupling between the ground wire and the phase conductors of a transmission line can be used to supply small loads in remote regions along the line. A theoretical analysis is presented in this paper to determine the parameters defining an equivalent circuit for the case of single as well as two insulated ground wires. Results are presented to show variations of the equivalent circuit parameters as functions of geometrical parameters of lines in the range of 300- 750 kV. Finally, some results of measurements on Hydro-Quebec´s lines are presented and compared with theoretical calculations.