FIELD: maintenance of aerial power lines with an insulated neutral conductor by contactless method, applicable for mobile location of a single-phase ground fault in a branched aerial power line with an insulated neutral conductor.
SUBSTANCE: the method provides for fixation of an emergency signal, then the electric and magnetic field strengths are measured as an emergency signal in succession in the point of branching and under each branch of the aerial power line, converted to harmonic components of the voltage and current signals proportional to them, with the aid of the Fourier transform for each harmonic the amplitude and the phase angles of the harmonic components of the voltage and current signals are determined, from the sequence of the values of the amplitudes of harmonic components of the voltage and current signals the i-th harmonic component with the maximum amplitudes of harmonic components of the voltage and current signals is separated, comparing them with the proportional maximum allowable amplitudes measured in the normal operating conditions of the power line, and according to the excess of the values of the amplitudes of the components of the voltage and current components of the separated i-th harmonic, the branch with a faulty condition, the direction to the point of the ground fault in it are determined according to the sign of the shift between the harmonic components of the voltage and current signals of the separated i-th harmonic, for the positive sign of the phase shift angle between the harmonic components of the voltage and current signals the direction of search "to the right" corresponds, and for the negative sign of the phase shift angle between the harmonic components of the voltage and current signals the direction of search "to the left" corresponds, the point of ground fault in this branch is determined according to the change of the sign of the phase angle shift between the harmonic components of the voltage and current signals of the separated i-th harmonic, measuring the strengths of the electric and magnetic fields, moving under the aerial power line along the faulty branch.
EFFECT: provided determination of the point of the single-phase ground fault within a short period of time with a high precision and convenience.
1 dwg, 6 tbl
