FIELD: electricity.
SUBSTANCE: invention is attributed to electrical power engineering. System phase voltages are recorded. Recorded voltages are compared with threshold level 2Upm. If the level is exceeded by any of phase voltages derivates of phase voltages are determined and their signs are compared. When they coincide and derivative module values exceed setting - double value of system line voltage derivative maximum after grounding arc extinction - zero-sequence voltage and its decade rate is determined by quadratic polynomial approximation. If voltage decade rate module is less than 0.1 Upm/ms and initial voltage module is greater than 0.1 Upm, the fact of OPAG is stated. Faulty phase is determined from maximum phase voltage derivative at the moment insulation breakdown.
EFFECT: simplicity, reliability and low time consumption of OPAG detection
4 dwg
