Research on Error properties and Influence Factors of Three-phase Combined Instrument Transformers Under Different Operating Conditions

Based on the three-phase detection method, a three-phase combined transformer error verification platform is designed and the error properties of three-phase three-element combined instrument transformers, including the interaction between the voltage and current parts are studied systematically. The experimental results show that the percentage of rated voltage/current and the secondary load have a great impact on the error properties of three-phase combined transformers. When the current and voltage parts of three-phase combined transformer are excited at the same time, it is found that due to the strong electromagnetic coupling, the mutual influence between the voltage and current transformer is large. Especially under the condition of 20% of the rated current, the influence of voltage transformer on current transformer error properties has exceeded the allowable range and cannot be ignored.