Identification of power system primary arcs based on pulse density

A diagnostic instrument for distinguishing primary arcs from other electrical discharges in an electric power system, the diagnostic instrument comprising:

• a receiver to receive, using an antenna, a radio frequency sensor signal generated by overhead power transmission or distribution lines;
• a detection circuit to detect noise pulses within the sensor signal produced by any nearby electrical discharge, the noise pulses comprising noise pulses caused by primary arcs and noise pulses caused by induced sparks, wherein primary arcs comprise electrical discharges occurring on a primary conductor or a secondary conductor, and wherein induced sparks comprise electrical discharges occurring on a structure that is physically common to, but electrically decoupled from, the primary conductor and the secondary conductor;
• a primary arc identification circuit configured for:
• counting the noise pulses for at least one time duration, wherein each said duration is less than one half cycle of the electric power system, and wherein said counting comprises counting noise pulses in a plurality of windows over a period of time;
• determining a measurement related to noise pulse density based on said counting, the measurement distinguishing primary arcs from induced sparks in the overhead power transmission or distribution lines, wherein said determining comprises determining a maximum of the counts of noise pulses in any of the windows over the period of time;
• repeating a plurality of iterations of said counting noise pulses in a plurality of windows over a period of time, wherein said determining comprises determining a statistical measure of the maximum of the counts of noise pulses in any of the windows over the period of time for the plural iterations;
• determining whether the measurement is in a range characteristic of primary arcs or in a range characteristic of induced sparks;
• and
• an output for indicating a result based on the measurement, wherein indicating a result comprises displaying an indication that a primary arc is detected when the measurement is determined to be in the range characteristic of primary arcs.

A diagnostic instrument for distinguishing primary arcs from other electrical discharges in an electric power system, the diagnostic instrument comprising:

• a receiver for receiving a signal;
• a detection circuit for sensing noise pulses on the signal caused by electrical discharges;
• a primary arc identification circuit operating to produce a measurement value relating to time density of the noise pulses in at least one time duration wherein each said time duration being less than one half cycle of the electric power system, and to determine whether the measurement value is in a range characteristic of primary arcs, as distinguished from other arc types different than primary arcs;
• and
• an output for indicating a primary arc detection result when the measurement value is determined to be in the range characteristic of primary arcs;
• wherein the measurement value is a mean over a plurality of iterations of a maximum count of the noise pulses in any of a plurality of windows over a period of time;
• and
• wherein the primary arc identification circuit further operates to determine whether high densities of noise pulses occur in one or both halves of the electric power system cycle, and to distinguish primary arcs from corona based on said determination whether high densities of noise pulses occur in both halves of the electric power system cycle.