Accuracy and Calibration of Instrument Transformers with Digital Output

Issues related to the accuracy and calibration of instrument transformers with digital output are presented, addressing both laboratory and field calibration. Both IEC and IEEE accuracy definitions are considered, and appropriate circuits for high-accuracy calibration are reviewed. An update on EURAMET EMPIR Futuregrid II project is provided, showing the latest efforts in enabling deployment of digital voltage and current sensors in the evolving grid. Finally, examples of the use of digital low power instrument transformers for practical field calibration of other instrument transformers are presented.