Patent ID: 9696367
Date: 2017-07-04
CPC Classifications: G01R

Claim:
1. A method comprising: selecting a measurement point to a fault in a three-phase circuit, the measurement point being located at an output of a power sub-station, the three-phase circuit having a loop circuit with an associated net fault line current and a ground current; electrically connecting a current sensor to the measurement point at the output of the power substation; selectively sensing the net fault line current using the current sensor and transmitting the sensed net fault line current to an electronic server over a network; at the electronic server, receiving the sensed net fault line current from the network and taking a derivative of the net sensed fault line current of the loop circuit as measured from the measurement point and determining an uncompensated inductive distance to the sub-cycle fault by obtaining a sum of a voltage level at the fault and a net fault voltage, and dividing the sum by the derivative of the net fault current; at the electronic server, determining a compensation inductive distance to account for the ground current of the loop circuit; at the electronic server, applying the compensation inductive distance to the uncompensated inductive distance to produce a compensated inductive distance to the sub-cycle fault; at the electronic server, determining a source inductance, the source inductance being measured from the measurement point looking back at the sub-station; at the electronic server, determining an accuracy of the calculated distance to the fault based upon the determined source inductance and without the use of faulted data; at the electronic server and based upon the calculated distance to the fault, determining and arranging a preventive maintenance and repair activity before the sub-cycle fault leads to an unscheduled fault and an unscheduled outage.