High Voltage Multi-Purpose Current and Voltage Electronic Transformer

The evolution of electronics technology and digital signal processing is making competitive methods and devices for the design and development of measurement transformers for HV systems deeply different from those based on the traditional electromagnetic principle. Several advantages are offered by the new solutions: higher metrological characteristics, cost-effective, compact size, lack of the typical problems of the traditional electromagnetic transformers (magnetic core saturation, magnetic resonance, bandwidth limits, etc.). In this paper a prototype of a novel HV electronic transformer is presented, with a combined structure which permits both voltage and current protective and measurements functions. The rated primary voltage and current are 145 /radic3 kV and 1000 A respectively. The developed transformer is compliant with IEC 60044-7 and IEC 60044-8 standards, assuring the 0.1 measurement precision class and satisfying also the 5P and 3P protection classes for current and voltage section respectively. A very interesting aspect that characterizes the design of the transformer is the mix of well-tested traditional technologies (like these employed for the voltage capacitive divider and for the current sensor) and very sophisticated electronics, thus allowing to obtain high measurement performances and advanced ancillary functions (like auto-diagnostic, fault-tolerance, auto-calibration, etc.).