This paper aims to evaluate the performance of commercial power quality meters. By using a high precision programmable voltage and current source, several meters are analyzed and compared. At first, At first, distorted three-phase voltage signals are applied to several kinds of PQ instruments, considering harmonics, sags, swells, as well as unbalanced voltages. Next, the features of these events are measured, compared and evaluated taking into account the different instruments. In further analysis, voltage and current signals are applied in different situations, with and without harmonic and imbalances, in order to obtain the measurements of electrical power. After analyzing the data generated in all these tests, efforts are focused on establishing a relationship between the error values of the measurements. Considering the percentages of errors, a score is assigned to each measurement instrument. This work is justified since Brazil is deploying a standardization in terms of power quality measurements aiming regulatory procedures and limit values of indices.