Stepping up AC-DC current up to 20 A

This paper describes the AC/DC current stepping up arrangement and results at the National Metrology Centre (NMC). Planar multi-junction thermal converters (PMJTCs) were used with a set of coaxial current shunts to build up the AC-DC current transfer standards for the range from 10 mA to 20 A at frequency range of 10 Hz to 100 kHz. Current level-dependence of the PMJTCs at low frequencies was determined experimentally. The resulted AC-DC differences agree well with known calibration with expanded uncertainties of less than 55 muA/A at 20 A for frequencies from 10 Hz to 100 kHz.