Optimisation of Inductive Voltage Instrument Transformers with Open-Core for High Frequency Applications

Power quality measurement has gained significant attention in recent years, driven by the swift “green transition” and the growing integration of renewable energy sources into the electrical grid. The latest revision of the primary instrument transformer standard, IEC 61869–1:2023, introduced new performance requirements for instrument transformers, specifically regarding transfer accuracy at higher frequencies. As a result, five new accuracy class extensions were added to define explicit performance standards. These requirements primarily target non-conventional instrument transformers, though there is a hypothesis that conventional instrument transformers could also meet these criteria. Additionally, most studies focus on power quality measurements for low- and medium-voltage transformers, where test circuits are simpler to establish. This paper, however, shifts focus to high-voltage testing of the transmission characteristics of instrument transformers, an area where test circuits are more complex and research is limited. The paper examines the performance of five distinct inductive voltage transformer prototypes, each featuring a different magnetic circuit. The findings will be based on measurement data obtained through low-voltage measurements, and other testing methods will also be discussed.