FIELD: electricity.
SUBSTANCE: according to the method, duration of reclosing dead time of sectionalising circuit breaker is compared to time between negative phase-sequence voltage surges, and when they coincide, ALT activation prohibition is introduced. According to invention, durations of short circuit current surges are compared to duration of protection activation of sectionalising circuit breaker. For that purpose, short circuit current is controlled at the beginning of the line fed from buses of the main power source, and when it appears, reading of the time is started, which is set equal to protection actuation time of sectionalising circuit breaker located in the main power source line adjacent to network ALT, and if short circuit current disappears at the moment of end of time reading, then further in the time equal to the reclosing dead time of this circuit breaker, occurrence of the second short circuit current surge is controlled, and when it appears, the time equal to protection activation time of sectionalising circuit breaker with acceleration is read, and if the second short circuit current surge disappears at the moment of end of this time, then the fact of permanent short circuit available in line is established and ALT prohibition signal is supplied.
EFFECT: enlarging functional capabilities of the method by its application for prohibition of network ALT to permanent, both two- and three-phase short circuits, and improving reliability and fidelity of the method.
2 dwg
