FIELD: electrical engineering.
SUBSTANCE: according to the method a) sampled is residual voltage (Vr) of three-phase electric system (30) of power supply and residual current (Ir) in the above said measuring unit to obtain sampled signal (UN) of the residual voltage and sampled signal (IN) of the residual current; b) filtered is in the first digital filter (41) sampled signal (UN) of the residual voltage and applied to it is a phase shift to extract a shifted in phase component of the filtered signal with a noninteger order of the main frequency and to obtain a shifted in phase filtered signal (UNH) of voltage; c) filtered is discrete signal (IN) of the residual current in the second digital filter to extract a component of the filtered signal with a noninteger order of the main frequency to obtain filtered signal (INH) of current; d) used is filtered signal (INH) and shifted in phase filtered signal (UNH) for calculating transient reactive power (QR) flowing through the said measuring unit; e) determined is the direction of a short circuit depending on a sign of the calculated transient reactive power (QR).
EFFECT: wider range of equipment.
5 cl, 10 dwg
