Comparison between hexa- and conventional E-type core three-phase transformers

The concept of power transformer design with a symmetric core construction (the hexa-transformer) provides a more compact solution compared to traditional technology based on an E-type core. This paper evaluates parameters of two 100 kVA three-phase transformers built according to both concepts. The evaluation includes calculations of induced voltages, inductances, core losses and weight differences. Further, the calculated parameters are compared with measured values. It is shown that, for the investigated transformer size and ratings, the compact design of the hexa-transformer yields up to 25% lower core losses, 40% smaller magnetization current and 12% lower core weight compared to the conventional E-core transformer.