Onsite calibration of a current transformer using a Rogowski Coil

This paper describes a reference current-measuring system for the onsite calibration of high-voltage current transformers. The reference current-measuring system consists of a Rogowski coil, a current shunt, two digitizing voltmeters, and a computer to control the voltmeters. The method of generation of the high current and the uncertainty of the calibration are discussed. The results of a calibration performed onsite on a 400-kV substation are presented. Uncertainties of 300 muA/A for ratio and 1 angular minute for phase displacement were achieved with this method onsite