A Method of Deriving Overall Accuracy for Single-Phase Watthour Meters

Results from a recent load research study indicated a significant amount of energy is accumulated at lighter loads where watthour meter accuracy is poorer. Although small inaccuracies of watthour meters at lighter loads may seem insignificant, they become large when applied to an entire meter population. A method was developed to establish at which loads watthour meters register energy consumption. Sampled meters spent 85 percent of the time and registered more than 40 percent of the total energy for a one-year period at lighter loads.