FIELD: electrical engineering; relay protective gear for power systems. SUBSTANCE: device has three-phase power circuit with current transformers interconnected in delta and connected in series with phase leads, current circuits, and threshold element (relay) that has equalizing coils with leads 1,3 and differential (running) coil with lead 6 both interconnected across leads 2 and 4; novelty is that pole leads are connected through current transformers of different phases to one of differential relays; first pole lead of first-phase transformer is connected to lead of first equalizing coil of differential relay, that of second phase, to pole lead of second equalizing coil of differential relay, and pole lead of third phase, to differential (running) coil lead of differential relay. In this way, reverse-sequence currents can be clamped by connecting one of differential relays to three-phase current protection circuits and that circuit does not include provision for zero-sequence current correction. EFFECT: improved sensitivity, extended regulation range of reverse-sequence phase current settings, simplified circuit arrangement, provision for unification of relays, reduced labor consumption and time required for device adjustment and maintenance. 5 dwg
