| 摘要 |
<p>A PN modulated signal is applied to a near end (25) of a buried electrical cable (26). The signal produces an initial pulse, a second pulse of energy reflected from a fault and a third pulse representative of the far end (27) of the cable, the time/distance (t) between the second and third pulses is stored. As the PN signal is continuously applied an operator, using an antenna (62) coupled monitor (30), walks along the cable (26) noting the time/distance (t) between the initial and third pulses. When this time/distance (t) equals the stored time/distance (t) 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 (25) of the cable (26, 86). 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 (26, 86), the arc is initialized by a high voltage low current signal and is maintained by a low voltage high current signal.</p> |
