Home Products Protection Relays DRAGON SERIESRTI D Transformer differential protection and control

RTI D Transformer differential protection and control

RTI D is designed to be used as a main Protection IED for a selective clearance of all kinds of short circuits in the Power Transformers of practically all voltage levels. Restricted Earth fault protection for a sensitive internal earth faults identification and clearance is also provided.

Depending on the application (EHV or HV) RTI D can be used for three-phase or single-phase power transformers.

The protection is suitable for all types of current transformers - iron-core and linearized (Rogowski coil).

 In case of missing a separate Bay control unit (BCU) a Local & Remote control functions are also included.

Relay protection functions***

  • Transformer differential protection
  • Transformer differential protection high stage
  • Four stages non-directional definite time/instantaneous overcurrent protection
  • Non-directional Inverse time overcurrent protection with 12 inverse time characteristics
  • Four stages non-directional definite time/instantaneous ground fault protection
  • Non-directional Inverse time ground fault protection with 12 inverse time characteristics
  • Negative Sequence overcurrent protection
  • Phase discontinuity detection
  • Restricted earth fault protection
  • Thermal overload protection
  • Second harmonic blocking (inrush restraint)
  • Breaker failure protection
  • Clockwise and anticlockwise phase rotation function
  • Trip circuits supervision
  • Current circuits supervision functions

*** All relay protection functions meet all ANSI and IEC standards' requirement

 Automation and remote control functions

Disturbance (Fault) Recorder 

  • Sampling rate – 1kHz / 2kHz
  • User defined trigger conditions and records duration
  • Recording mode -overwrite (ring buffer) or saturate
  • Each sample consists of instantaneous values of all analog and digital values
  • File format - COMTRADE

Data Logger 

  • Sampling rate – 50 / 10 / 1Hz
  • User defined trigger conditions, records duration and values
  • The function could be enabled or disabled
  •  Recording mode -overwrite (ring buffer)
  • Each sample contains RMS values of all selected analog values
  • File format - COMTRADE

Event Recorder

  • Up to 1000 records
  • Each event consists of information about the event’s type, some additional data (such as pick-up current, voltage, the time elapsed and so on) and the time stamp of the event (year, month, day, hour, minute, second, millisecond)
  • Recording mode - overwrite


  • SCADA communication - IEC 61850, IEC 60870-5-103, IEC 60870-5-104, MODBUS RTU/TCP
  • Configuration tool - ROCON MMI protocol
  • Web-based interface - HTTP
  • Time synchronization - PTP (IEEE 1588), NTP / SNTP, IRIG-B or PPS
  • File system access – FTP

Configuration, setting and administration

  • Web server


  • Optional extension with I/O modules