HIGH AC CURRENT CALIBRATION SYSTEM BASED ON ROGOWSKI COIL

MIKES is the national metrology institute (NMI) of Finland and one of its key tasks is to provide calibration services to both domestic and international customers. The high AC current calibration method of MIKES is based on a Rogowski coil used as a current transducer. This paper discusses the structure and properties of the current calibration system and the theory behind it. Typically Rogowski coils are not used in accurate high AC current measurements because their accuracy is sensitive to changes in conductor geometry and in measurement arrangements. However, we have improved the measuring accuracy of Rogowski coil by installing a precision coil on a custom coaxial busbar and compensating its temperature dependence. Rogowski coil is also routinely calibrated against a current shunt in…