System and method for locating faults in electric power cables

A method for locating an insulation defect type fault occurring in a multi-phase power distribution system, such system comprising an urban network with multiple cables branched along its length from a predetermined monitoring point, said method comprising the steps of:

• a. applying a high voltage supply into said multi-phase power distribution system sufficient to break down an insulation defect and induce a transient fault pulse;
• b. injecting into said multi-phase power distribution system at said monitoring point along said multi-phase power distribution a timing pulse a known time delay (T.sub.D) after the arrival of said transient fault pulse at said monitoring point;
• c. measuring separate timing intervals (T.sub.m) between arrival times at each of a plurality of receiving points located on a plurality of said branched cables of said multi-phase power distribution system of said transient fault pulse and said timing pulse;
• and
• d. determining the location of said insulation defect on one of said branched cables of said multi-phase power distribution system based on said timing intervals (T.sub.m), said known time delay (T.sub.D) and known propagation velocities of electric power cables within said multi-phase power distribution system.

A system for locating a fault in a multi-phase power distribution system as said fault occurs, such system comprising an urban network with multiple cables branched along its length from a predetermined monitoring point, said system comprising:

• a. a first means for sensing the arrival of a transient fault signal at a monitoring point along said multi-phase power distribution system;
• b. a means for injecting pulses at said monitoring point into said multi-phase power distribution responsive to said first means for sensing;
• c. a time delay means at said monitoring point for interposing a delay of a specific known time interval before injection of said pulses after sensing the arrival of said transient fault pulse;
• d. second means for sensing the arrival of said transient fault pulse and said injected pulse at each of a plurality of receiving points located on said branched cables along said multi-phase power distribution system;
• and
• e. a means for measuring time intervals responsive to said second sensing means occurring between sensing the arrival of said transient fault pulse and said injected pulses at each of said plurality of receiving points.

A system for locating an insulation defect in a multi-phase power distribution system after the occurrence of said insulation defect, such system comprising an urban network with multiple cables branched along its length from a predetermined monitoring point, said system comprising;

• a. a means for applying a high voltage supply into said multi-phase power distribution system sufficient to break down said insulation defect and induce a transient fault signal;
• b. a first means for sensing the arrival of said transient fault signal at a monitoring point along said multi-phase power distribution system;
• c. a means for injecting pulses at said monitoring point into said multi-phase power distribution responsive to said first means for sensing;
• d. a time delay means at said monitoring point for interposing a delay of a specific known time interval before injection of said pulses after sensing the arrival of said transient fault pulse;
• e. second means for sensing the arrival of said transient fault pulse and said injected pulse at each of a plurality of receiving points located on a plurality of said branched cables along said multi-phase power distribution system;
• and
• f. a means for measuring time intervals responsive to said second sensing means occurring between sensing the arrival of said transient fault pulse and said injected pulses at each of said plurality of receiving points.