Cable Fault Location

Cable fault location is the process of finding and pinpointing an electrical fault, such as a break in the insulation, inside a buried or otherwise inaccessible cable. Pre-location narrows down the distance to the fault before any digging begins, either by sending a pulse down the cable and timing its reflection back from the fault at half the cable own propagation speed, or, in the transient method, by creating a controlled breakdown at the fault site and analyzing the traveling waves it sends back from each end of the cable. For underground cables, loop tests built on bridge circuits are also used: the Murray loop test applies Wheatstone bridge principles against a sound reference cable run alongside the faulty one, while the Varley loop test uses a fixed resistor with a variable resistance in the faulted section and is more sensitive to high impedance faults. Mobile shock discharge generators and dedicated cable test vans are the standard field equipment, and a fault is normally first classified by type, such as a screen, phase, sheath or moisture related fault, before pre-location, route tracing and final pinpointing are carried out. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/