AbstractThe traceability of measurements performed to gauge information about the operation of electrical power systems under nonsinusoidal conditions is an important and live issue, usually neglected by the technical Standards. A generalized definition of the “composite error” is proposed in this paper as a meaningful index for the metrological characterization of voltage and current transducers in steady‐state nonsinusoidal conditions. In this connection, the relationship among the composite error, the classical ratio and phase‐angle errors and other parameters characterizing the waveforms of the transduced quantities are pointed out. Finally, problems involved in the measurement of the composite error in steady‐state distorted conditions are dealt with and the results of some experimental work are presented.