To examine these characteristics of primary converters, we used themetrological system shown in Fig. 2. The OMICRON CMC 356 hardware andsoftware system is used as a programmable source of electric signals with a widefrequency range from 0 to 1 kHz. Keysight 3458A multimeters are intended forhighly accurate measurement of signals from a reference current transformer andthe one undergoing calibration. Multimeters are controlled from a PC with the aidof certified software (EnergoEtalon).