Calibration system for electronic instrument transformers with analogue and digital outputs

A system calibrating electronic instrument transformers with analogue and digital outputs is described. Its design is based on International Electrotechnical Commission (IEC) standards 60044-7, 60044-8 and 61850-9-1. The measurement uncertainty of the system is evaluated to be less than 0.05% for ratio error and less than 2 min for phase error.