Traceable Characterization of Low Power Voltage Instrument Transformers for PQ and PMU Applications

Diffusion of digital technologies in transmission and distribution substations is fostering utilization of low power instrument transformers for use in in metering, protection, as well as in monitoring and control applications. From the metrological point of view, new reference systems and procedures are needed to ensure traceable measurement, in particular when these low power sensors are coupled with phasor or power quality measurement unit, to identify their uncertainty contribution in the evaluation of the output parameters. In this scenario, a reference set-up for the characterization of voltage sensors with analog or digital output is described. First examples of characterization of a low power voltage transformer in presence of dynamic and power quality signals are shown.