Grid Ready Flexible Transformer

What if There Was a Better Technical Solution?

Prolec GE Monterrey developed a new patented technology to offer a transformer with a flexible impedance range and multiple low voltages, the Grid Ready Flexible Transformer.

Factory Test Validation

To validate this new technology, Prolec GE developed a full-scale prototype:

  • 60/80/100 MVA, 165-57.5/69/80.5 kV, with on-load tap changer

The unit was fully tested according to ANSI/IEEE standards at all LV ratings: (three sets of dielectric tests), heat run, excitation, losses and noise.

Field Validation

After factory test completion, the prototype was shipped to a US utility substation, where it was installed and energized. Field tests include continuous monitoring of critical performance parameters and on-line impedance variation to validate this feature in a real electrical grid condition.


Online 24 hour surveillance of critical parameters in the transformer:

  • 35 sensors installed measuring load, voltage, gases, temperature, etc.
  • Remote data collection and analysis; all performance data is analyzed by Prolec GE technical team at the factory


  • Application: Interconnection autotransformers
  • Phases: 3 phase units
  • Taps: OTLC and DETC
  • Capacity: 80 to 750 MVA three phase (top capacity rating)
  • Voltage rating HV: Up to 345 kV
  • LV multiple ratings: 2 or 3 voltage ratings (up to 230kV)
  • Impedance ranges: Between 6 to 12 pp of the Z% (i.e. from 4%-16%, depending on voltage ratio and system requirements)


  • Lower asset management cost for utilities
  • Permanent replacement—avoid additional installation costs compared to temporary alternatives
  • Designed to meet customer specifications and particular requirements
  • On-line or de-energized Impedance change (based on customer preference)
  • Additional benefits of on-line impedance change include improved short circuit withstand and better reactive power management in the substation
  • Transformer health management with a complete set of sensors and remote monitoring
Grid Ready Flexible Transformer photo with project team Grid Ready Flexible Transformer in substation Grid Ready Flexible Transformer in a substation Prolec GE Grid Ready Flexible Transformer in a substation