Abstract: A PN modulated signal is applied to an end of a network electrical distribution circuit. The signal produces a snapshot trace of energy reflected from various discontinuities along the circuit, including a fault. Because the fault absorbs a large part of the energy in the applied signal, reflections from discontinuities in the same branch as the fault but farther from the input are reduced in amplitude. By knowing the position of the branches and various discontinuities, such as transformers, the position of the fault can be logically determined. If the fault is a high resistance fault a high voltage pulse is applied to the end of the circuit. The PN signal is initially sensed at a time when the fault has a low resistance because of arcing due to the high voltage pulse.

Abstract: A PN modulated signal is applied to a near end of a buried electrical cable. The signal produces an initial pulse, a second pulse of energy reflected from a fault and a third pulse representative of the far end of the cable. The time/distance between the second and third pulses is stored. As the PN signal is continuously applied an operator, using an antenna coupled monitor, walks along the cable noting the time/distance between the initial and third pulses. When this time/distance equals the stored time/distance the operator is standing over the fault. If the fault is a high resistance fault a high voltage pulse is applied to the near end of the cable. The PN signal is initially sensed at a time when the fault has a low resistance because of arcing due to the high voltage pulse. To reduce stress on the cable, the arc is initialized by a high voltage low current signal and is maintained by a low voltage high current signal.