Equivalent Circuit Parameters of Power Tap-Off from Insulated Shield Wires of High Voltage Transmission Lines at Different Rated Voltages

Power tap-off from shield wires of high voltage overhead transmission lines is associated with electrostatic induction voltage of shield wire and equivalent capacitance of power tap-off circuit, which will be affected by the rated voltage. In this paper, the equivalent circuit parameters of typical transmission lines at rated voltages from 110 kV to 1000 kV in China are investigated. The electrostatic induction voltage and equivalent capacitance are calculated by Maxwell's electrostatic equations as well as Thevenin’s equivalence principle. The results show that the electrostatic induction voltage is increased with the increase of the rated voltage, while the equivalent capacitance is slightly decreased with the increase of the rated voltage. The conducting line arrangement is also considered. The relationships between the equivalent circuit parameters and the rated voltage are built up, which can provide a reference for the power tap-off from insulated shield wires.