Universal protection relay

Universal protection relay – SIPROTEC 7SX800


From Siemens | for the Future | for You. The universal protection relay SIPROTEC 7SX800 has the high development and manufacturing quality of Siemens, is equipped for future challenges and is predestined for beginners and professionals alike. This efficient and compact device protects your feeders, lines and motors in the medium-voltage power grid in the utility and industrial sectors.

SIPROTEC 7SX800 - universal protection relay

SIPROTEC 7SX800 - the universal protection device for all your medium-voltage applications impresses with high performance and an extensive function library. You now only need one device for the various protection types with different configurations already predefined in application templates.


Highlights of SIPROTEC 7SX800

  • Slim design with a high number of IOs
  • Virtual testing with SIPROTEC DigitalTwin
  • IoT connectivity for easy access to your device data and associated fast response times
  • Embedded cyber-security features to protect your device and maximize power grid availability
  • Intuitive device operation with the web user interface
  • Proven engineering tool DIGSI 5

SIPROTEC 5 Compact – Universal protection relay

Functions & applications

Universal protection relay SIPROTEC 7SX800


  • Directional and non-directional overcurrent protection with additional functions
  • Detection of ground faults of any type in compensated or isolated electrical power systems using the following functions: 3I0>, V0>, transient ground fault, cos φ,
    sin φ, harmonic detection, dir. detection of intermittent ground faults, and admittance
  • Optimized operate times thanks to directional comparison
  • Motor protection functions: Startup time supervision, thermal overload protection for stator and rotor, restart inhibit, unbalanced-load protection, load-jam protection
  • Stator and bearing-temperature monitoring via temperature sensors with external RTD unit
  • Sensitive ground-fault protection (directional, non-directional) to detect stator ground faults
  • Controlled automatic reclosing of overhead line sections
  • Overvoltage and undervoltage protection
  • Frequency protection and rate of frequency change protection for load-shedding applications
  • Underfrequency load shedding in case of underfrequency, taking into consideration changed infeed conditions due to decentralized power generation
  • Power protection, configurable as active or reactive-power protection
  • PQ – Basic: Voltage unbalance; voltage changes: Overvoltage, dip, interruptions; TDD, THD, and harmonics
  • Directional reactive power undervoltage protection (QU protection)
  • Control, synchrocheck, and switchgear interlocking protection
  • Circuit-breaker failure protection and reignition monitoring
  • Graphical logic editor
  • Single-line representation


  • 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-suppression-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
  • Protection and interfacing of regenerative infeeds
  • Protection and monitoring of double-star point capacitor banks
  • Protection against thermal overload of the stator from overcurrent, cooling problems, or pollution and of the rotor during startup due to frequent startups, excessively long startups, or blocked rotor
  • Monitoring for voltage unbalance or phase outage
  • Monitoring the thermal state and the storage temperatures with temperature measurement
  • Detection of idling drives of pumps and compressors, for example
  • Detection of ground faults and short circuits in the motor
  • Protection against instability due to undervoltage
  • Detection and recording of power-quality data in the medium voltage and subordinate low-voltage power system
  • Load-shedding applications
  • Retrofit


  • Compact and cost-effective universal protection device for a wide range of applications
  • Safety thanks to powerful as well as tried-and-tested protection functions
  • Simple operation thanks to graphical color display including single-line representation
  • Intuitive device operation using Web UI
  • Cybersecurity in accordance with NERC CIP and BDEW Whitepaper requirements (for example, logging security-related events and alarms) available as standard
  • Full compatibility between IEC 61850 Editions 1, 2.0 and 2.1