Patent ID: 7535233

Claim:
An apparatus comprising: at least one Rogowski coil positioned on an electrical power transmission line within an AC electrical power distribution network that operates at a fundamental power frequency, the Rogowski coil: generates a first signal in which a first traveling wave current is filtered from a current component corresponding to the fundamental power frequency by sensing a change in current in the electrical power transmission line, wherein the first traveling wave current results from a fault on the electrical power transmission line of the network and a value of the first signal is proportional to the change in current, and generates a second signal in which a second traveling wave current is filtered from the current component corresponding to the fundamental power frequency by sensing a change in current in the electrical power transmission line, wherein the second traveling wave current results from the fault on the electrical power transmission line and a value of the second signal is proportional to the change in current; and a processor: receives the first signal and the second signal, compares the value of the first signal and the value of the second signal to a threshold value, if one or more of the value of the first signal and the value of the second signal exceeds the threshold value, determines a time difference between the first signal and the second signal, and determines, based on the time difference, where on the line the fault occurred relative to a location of a reference impedance mismatch.