Section 2 REF615 overview2.1 OverviewREF615 is a native IEC 61850 feeder protection IED for selective short-circuit,overcurrent and earth-fault protection. It is applicable to all types of radial isolatedneutral networks, resistant earthed networks and compensated networks. REF615 ispart of a product family that will cover many protection applications for utility andindustry customers.The IED features draw-out-type design, compact size and ease of use. Depending onthe IED variant, the protection functions may include:• Three-phase non-directional overcurrent protection, 4 stages• Three-phase directional overcurrent, 3 stages• Directional earth-fault protection, 3 stages• Non-directional (cross-country) earth fault, using calculated I0• Non-directional earth fault, 3 stages• Transient/intermittent earth-fault protection• Non-directional sensitive earth fault• Negative-sequence overcurrent protection, 2 stages• Phase discontinuity• Three-phase overvoltage protection, 3 stages• Positive-sequence undervoltage protection• Negative-sequence overvoltage protection• Residual overvoltage protection, 3 stages• Three-phase undervoltage protection, 3 stages• Three-phase transformer inrush detector• Three-phase thermal overload, lines and cables• Circuit-breaker failure protection• Electrically latched lockout relayDepending on the IED variant, the optional functions may include:• Auto-reclose• Arc protection, three lens sensors for arc detection1MRS756378 D Section 2REF615 overviewREF615 15Application Manual
