An Improved Current-Comparator-Based Power Standard With an Uncertainty of 2.5 $\mu\hbox{W/VA}\ (k = 1)$

An improved power standard derived from a current comparator power bridge for calibrating active/reactive power and energy meters under sinusoidal conditions is described. Measurements can be made at any power factor from zero lag through unity to zero lead, at positive or negative power, at 120 V, 5 A, and 50 or 60 Hz. The improved power standard has an estimated uncertainty of not more than 2.5 μW/VA at k = 1. Special high-accuracy current and voltage range extenders have been incorporated to extend the current and voltage ranges up to 200 A and 1200 V, respectively.