The authors developed an ac standard shunt (rated IOA, 0. I 0) for the frequency from dc to IOkHz that has highly stable resistance value and small phase angle error. By using this ac standard shunt, ac power and current may be measured with high accuracy.The stability and uncertainty of the shunt correspond to 3ppm with regard to ac power measurement at IWz.

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A new digital calibration system for ac power and energy met was developed at Japan Eledlic Meters Inspection Corp. (JEMIC) and its performance has been evaluated at National Reseath Council of Canada (NRC). The results at power frequency were betterthan 20pW/W ofapparent power at any power factor settings. IntrdudnGenerally, most of high precision power/eneigy standards are established based on cment comparator [1], thermocouple, etc. On the other hand, recent digital techniques can provide simple approaches forpower/energy meem ent with high accuracy. The digital calibration system described in this paper uses digital techniques to achieve high prwision power measurement Voltage, cuntnt, and phase angle applied to power/energy meter under test are meared individuaRy, and then active/mwative power is determined by calculating results ofthese measurements.

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