Description The SIPROTEC 7SJ81 has been designed for a cost-effective and compact protection of feeders and lines in medium-voltage systems. With its flexibility and the powerful DIGSI 5 engineering tool, the SIPROTEC 5 device offers future-oriented solutions for protection, control, automation, monitoring, and Power Quality - Basic. Main function Feeder and overcurrent protection Inputs and out- 4 current transformers, 11 binary inputs, 9 bi-puts nary outputs 4 current transformers, 18 binary inputs, 14 binary outputs 4 current transformers, 4 voltage transformers, 11 binary inputs, 9 binary outputs 4 current transformers, 4 voltage transformers, 16 binary inputs, 11 binary outputs Hardware flexi- Different hardware quantity structures for bility binary inputs and outputs are available in the 1/3 base module. 1 plug-in module position, available with large or small display Housing width 1/3 x 19 inches Applications • Detection and selective 3-pole tripping of short circuits in electrical equipment of star networks, lines with infeed at one or two ends, parallel lines and open-circuited or closed ring systems of all voltage levels • Detection of ground faults in isolated or arc-suppres-sion-coilground power systems in star, ring, or meshed arrangement • Backup protection for differential protection devices of all kind for lines, transformers, generators, motors, and busbars • Universal power protection SIPROTEC 7SJ81 • Simple load shedding applications • Detection and recording of power-quality data in the mediumvoltage and subordinate low-voltage power system Functions DIGSI 5 permits all functions to be configured and combined as required. • Directional and non-directional overcurrent protection with additional functions • Detection of ground faults of any type in isolated or arc-suppression-coil-ground power systems using the following functions: 3I0>, V0>, transient ground-fault function, cos 0, sin 0, dir. detection of intermittent ground faults, harmonic detection, and admittance measurement • Detection of intermittent ground faults with automatic blocking of statically measuring functions to avoid message and fault-record floodingArc protection (note the resulting communication restrictions) • Overvoltage and undervoltage protection • Frequency protection and frequency change protection for load shedding applications

Power protection, configurable as active or reactive power protection Directional reactive power undervoltage protection (QU protection) Control with switchgear interlocking protection Synchrocheck Simple, fast, and secure access to the device via a standard Web browser to display all information and diagnostic data, vector diagrams, singleline and device display pagesTime synchronization using IEEE 1588 Standard fault recording (buffer for a max. record time of approx. 40 sec. at 2 kHz) Circuit-breaker failure protection Detection of current and voltage signals up to the 50th harmonic with high...