Abstract: A method and apparatus for measuring impedance of grounding system wherein a transient electric current is injected at the ground system under test while measuring the a transient ground potential difference, as well as the injected electric current. The ground potential difference is measured with respect to several points on the earth's surface at small distances from the test system. These measurements are processed by computer software which filters noise, corrects voltage and current transducer errors, and estimates the test system ground potential rise with respect to remote earth. Correction algorithms are used to remove irregularities in the frequency response of the voltage and current transducers and analog filters. The filtered and corrected measurements are used to estimate the ground impedance as a function of frequency. For this purpose, a parameter estimation procedure is used which takes into consideration the geometric arrangement of the voltage and current probes.

Abstract: A system for detecting a high impedance fault in a phase conductor having a potential device connected to the phase conductor, the system including a signal injection device having an input from the potential device which detects a reduction in voltage at the phase conductor and outputs a first signal in response to detecting a reduction in voltage at the phase conductor and a signal receiver which receives the first signal and provides a second signal to an interruption device in response to having received the first signal to cause the interruption device to open the circuit to the phase conductor.