Transformer terminal RET 541

The RET 541 transformer terminal is designed for the protection, control, measurement and supervision of two-winding power transformers and power generator-transformer blocks in distribution networks

Not active product since 2022

The RET 541 terminals are loaded with functionality to suit your application. Besides the three-phase stabilized current differential function featuring 2nd and 5th harmonic restraint, the basic version terminals incorporate three-phase over-current, non-directional earth-fault, restricted earth-fault, transformer thermal overload and phase unbalance protection.

These multi-version terminals further include over-voltage and under-voltage supervision, directional earth-fault, residual voltage and over-excitation protection, over-frequency and under-frequency protection, and under-impedance protection. Enhanced with an optional automatic voltage regulator function the terminal forms an integrated transformer management unit.

A special control version terminal, which includes just voltage regulator and control functions, is also available. 


  • Transformer protection relay

Product benefits

  • Withstands harsh environments e.g. in heavy industry, marine and offshore applications
  • Programmable logic functions (PLC)
  • Wide support for different communication protocols
  • Optical communication for fast disturbance-free communication

Product features

  • Three-phase current differential protection with stabilized and instantaneous stages for fast and selective winding short-circuit and interturn fault protection
  • Optional automatic on-load tap-changer control function for single or parallel transformers
  • Support for IEC 61850 and Profibus DP protocols through adapters
  • 15 binary inputs and 12 output relays

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