Both ratio error and phase angle error in potential transformer(PT) are critically affected by used burden, connected in parallel to the secondary terminal of the PT. Thus precise measurement of burden value is very important for the evaluation of PT An automatic measurement system has been developed for the measurement of burden value and power factor of a burden. The ac voltage, current and power of the burden are measured precisely, and the burden value and power factor were calculated from these measured values. The resistance and inductance values of the tested burden are also calculated. The overall measurement uncertainties are calculated and reported with the burden value and power factor. The best measurement uncertainty for the burden measurement with the developed automatic measurement system was estimated to be 0.5 $\%$.