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Ac Impedance Measurements Used to Locate Faults in Mining Power Cables.
NTIS: PB 275 815 :19 pages
Various alternating current (ac) methods can localize faults in mining power cables. Several methods considered by the Bureau of Mines in this report are the murray loop for short circuits, wherein a bridge provides proportional distance to the fault; capacitance measurements for open conductors; inductance measurements for shorted conductors; phase comparison, high speed recordings of voltage and current in the faulted state are compared with normal voltage and current with the difference being a function of impedance change and impedance change being a function of fault location; and standing wave measurements, detecting the resonance of the length of cable to a fault (either short or open). Portable capacitance bridges are presently available for the second method, and the fourth method is well developed for use on large power distribution systems. Because it utilizes pulses rather than ac, the time domain reflectometer (tdr) method of fault locating was not included in this investigation. However, a comparative evaluation between this versatile method and the murray loop might prove advantageous in locating high resistance faults.
IH; Report of Investigations
NTIS Accession No.
NTIS: PB 275 815
Page last reviewed: May 5, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division