Multifunction protection

Multifunction protection – SIPROTEC 7SJ66


SIPROTEC 7SJ66 is a numerical protection, control and monitoring device.  SIPROTEC 7SJ66 is features flexible protection functions. Up to 20 protection functions can be added according to individual requirements. Thus, for example, a rate-of-frequency-change protection or reverse power protection can be implemented. The relay provides control of the circuit-breaker, further switching devices and automation functions. The integrated graphical logic editor (CFC) allows the user to implement its own functions, e. g. for the automation of switchgear (interlocking). The communication interfaces support the easy integration into modern communication networks.

Industry Mall

Select and buy

Multifunction protection SIPROTEC 7SJ66

Features & functions



  • Spring-type terminals
  • 4 current transformers
  • 4 voltage transformers
  • 16 to 36 binary inputs
  • 7 to 23 output relays
  • Graphic or 8 line display

Communication interfaces


  • System port:
    – IEC 61850
    – DNP TCP
    – IEC 60870-5-103
    – Modbus RTU
    – DNP3
  • Electrical and optical interface
  • RSTP (Redundancy Protocol for Ethernet)
  • Service interface for DIGSI 4 or RTD-Box
  • Front USB interface for DIGSI 4
  • Time synchronization via IRIG B, DCF77



Protection functions

  • Overcurrent protection

  • Directional overcurrent protection

  • Sensitive directional ground-fault detection

  • Displacement voltage

  • Intermittent ground-fault protection

  • Directional intermittent ground fault protect

  • High-impedance restricted ground fault

  • Inrush restraint

  • Motor protection

  • Overload protection

  • Temperature monitoring

  • Under-/overvoltage protection

  • Under-/overfrequency protection

  • Rate-of-frequency-change protection

  • Power protection (e.g. reverse, factor)

  • Undervoltage controlled reactive power protection

  • Breaker failure protection

  • Negative-sequence protection

  • Phase-sequence monitoring

  • Synchro-check

  • Fault locator

  • Lockout

  • Auto-reclosure
  • Admittance ground-fault protection


Control functions/programmable logic

  • Commands for control of CB and of isolators

  • Graphical visualization of switch positions

  • Control via keyboard, binary inputs, DIGSI 4 or SCADA system

  • User-defined logic with CFC (e.g. interlocking)

Monitoring functions

  • Operational measured values V, I, f

  • Energy metering values Wp,Wq

  • Circuit-breaker wear monitoring

  • Slave pointer

  • Trip circuit supervision

  • Fuse failure monitor

  • 8 oscillographic fault records with a sampling rate of 1.6 kHz

  • Motor statistics
  • Security log



  • English, Spanish, Russian, Polish and Turkish


  • Line and feeder protection: 
    Protection of high and medium voltage networks with earthed (grounded), low-resistance grounded, isolated or compensated neutral point

  • Motor Protection: 
    Suitable for asynchronous machines of all sizes

  • Backup Protection: 
    The relay performs all functions of backup protection supplementary to transformer differential protection


Downloads and services

Retrofit and enhancement services

Retrofit and enhancement services

Extend the lifespans of your energy system and thereby significantly reduce your costs of ownership with our retrofits and enhancement services for energy automation.

Power Academy training services

Power Academy training services

Our goal is to prepare you for new professional challenges in power transmission and distribution. We offer professional training courses with different training methods like Virtual Classroom Training, Classroom Training, WBTs, Webinars and Blended Learning. You can choose between open enrollment training courses, customized training courses, workshops or long-term trainings (curricula).

Energy Automation and Digital Grid Newsletter


Receive news about the Digital Grid and Energy Automation portfolio and offerings!

Energy Automation Webinars

Energy automation webinars

Learn more in one of our energy automation webinars for protection and substation automation engineers and experts.