Description High impedance protection is applied where faults must be cleared in the shortest possible time and where discrimination must be ensured. High impedance schemes can provide low fault settings. The 7SR23 DAD provides comprehensive, configurable high impedance protection with enhanced functionality and performance. Relay functionality is accessed via a familiar user friendly interface. Main Function Phase segregated high impedance differential protection / high impedance REF / Earth Fault Inputs and Outputs 4 Current Transformers with 1A and 5A Inputs, 9 or 19 Binary Inputs and 8 or 16 Binary Outputs Communication Front USB, Rear RS485, Additional optional comms interfaces as below. Housing Size E6 or E8, 4U high withdrawable design Benefits • Operating time <20ms (1 cycle) • High impedance busbar protection with IEC61850 • Calculation tool provided for relay and metrosil/ stabilising resistor settings requirements • Additional flush mounted box (metrosil/stabilising resistors) available to save internal panel space Applications • 3 phase high impedance differential protection is typically applied to busbar, connectors, autotransformers, reactors and motors. • Restricted earth fault protection is typically applied to provide protection of transformer windings. • The CT supervision function provides monitoring of CT secondary wiring connections. • The relay can be configured to provide the following modes of operation: 3 pole Diff + REF, 3 Pole Diff + EF, REF1 + REF2

Standard Monitoring Functions • Primary and secondary differential currents • Binary Input/Output status • Trip circuit healthy/failure • Time and date, Time and synchronizing commands • Fault, Event and Waveform records Data Communications Standard Communications Ports Communication access to relay functionality is via a front USB port for local PC connection or rear electrical RS485 port for remote connection CT50 CT Supervision User Programmable Logic User Interface • 20 character x 4 line backlit LCD • Menu navigation keys • 3 fixed LEDs • 8 or 16 Programmable Tri-colour LEDs (Option) Additional...