FIELD: electrical engineering; microelectronics.
SUBSTANCE: method for determining a single-phase ground fault (hereinafter referred to as SGF) in a power transmission line (hereinafter referred to as power lines) of a three-phase network with an isolated neutral, characterized by the fact that in the event of a breakdown of phase insulation to the ground, the current Io and voltage Uo are controlled during the discharge process of the electrical capacitance formed by the current-carrying parts of the damaged phases and grounded parts of the network, register the phases Io and Uo at beginning (1) of the phase insulation breakdown process to ground, record the continuity of current flow Io from the beginning to the end of the phase insulation breakdown process, register phases Io and Uo at the end (2) of the phase insulation breakdown process to ground. If, at initial moment (1) of the breakdown, simultaneity of occurrence and the opposite sign direction of the current Io and voltage Uo are recorded, continuity of the flow of the discharge current of the electrical capacitance is recorded, the maximum voltage Uo is recorded at moment of time (2) of the end of the flow of the capacitance discharge current, then the SGF in the controlled power lines is registered.
EFFECT: improved selectivity and reliability of protection against single-phase ground faults, timely detection of damaged power lines, preventing the transition of the fault to phase-to-phase through the ground, further development of the accident, emergency shutdown of the consumer, equipment damage.
1 cl, 1 dwg
