Measurement and Interpretation of Ground Impedance of Ground Impedance of Substations by Non-Conventional Fall-of-Potential Methods

摘要

Impedances of four grounding grids were reliably measured, using tuned-frequency test equipment operating close to the system operating frequency. The measurements were carried out by a non-conventional Fall-of-Potential method whereby the current injection and potential test leads form an angle of approximately 90° in order to determine the degree of error introduces into the measured apparent impedances by inductive, capacitive, and conductive coupling between the test leads, grounding grids, overheas ground wires, buried grounding cables and current return electrode, detailed computer models of the systems under test were created in order to simulate the measurements. The measured grid impedances are corrected for these interferences and agree well with the computed values.