Transformer Protection System

Three-Winding Protection for Transformers of All Sizes


Reduce project and ownership costs—

  • Standardization for 2- and 3-winding differential applications
  • Commissioning tools to speed factory acceptance testing and field start-up
  • Configurable and selectable elements to meet protection challenges for different winding types, CT connections, and grounding of transformers
  • Programmable I/O for advanced scheme logic applications
  • Meets ANSI and IEC relay compliance standards
  • Integral metering, event logging, communications and waveform capture

Enhance security and operational use—

  • Dual slope restrained differential, high-set unrestrained differential and restricted earth fault differential elements provide excellent unit protection
  • Unique 2nd and 4th harmonic restraint for enhanced security on transformer energizing (inrush detection). 5th harmonic restraint for security during overexcitation events
  • Overexcitation (V/Hz) element for extended asset protection
  • Undervoltage and underfrequency elements for load shedding applications
  • Phase and ground overcurrent elements for back-up protection
  • Optional breaker failure protection and breaker monitoring for each winding input.


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