FIELD: electricity.
SUBSTANCE: invention is attributed to the field of electric engineering and can be used for protection of power supply grids. For protection of parallel lines of the power supply grid the first protective instrument (13a) is connected to the first line (11a) of the power supply grid for registration of measured values, which characterise working condition of the first line (11a). The first protective instrument (13a) via a communication connection (15) is connected to the second protective instrument (13b) located nearby. In order to increase reliability and selectivity during monitoring of parallel lines, a method is proposed, in which the second protective instrument (13b) is connected to the second line (11b) of the power supply grid stretching in parallel to the first line (11a). Both protective instruments (13a, 13b) exchange measured data recorded by them relative to their appropriate line (11a, 11b), and/or signals produced from these measured values. Each protective instrument (13a, 13b) is made as capable of performing a protective function for its appropriate line (11a, 11b) when performing the main logic (25) of protections. Each protective instrument for performance of its main logic (25) of protection involves measured values registered on its own line (11a), and also measured values and/or signals accepted from another protective instrument (13b).
EFFECT: increased reliability and selectivity of decisions on working conditions of parallel lines of a multi-phase power supply grid.
23 cl, 11 dwg
