Determination of Core Losses in Open-Core Power Voltage Transformers

Power voltage transformers (PVTs) are becoming increasingly present in different substation solutions on a world scale. Such units that are based on the open-core concept introduce several advantages in terms of transformer performance and reliability. This paper provides context for distinct open-core losses, expanding in detail on a measurement-based method for determining both total and specific losses in the open core. The approach is demonstrated on several core model configurations with varying parameters. Apart from loss measurement, the presented core configurations were used to determine and verify the distribution and magnitude of all flux density vector components. The proposed approach is validated by various accompanying measurements but also through comparison with loss measurements performed on several PVT units intended for commercial application.