Operational and Economic Assessment of 750 kVA Three-Phase and Three 250 kVA Single-Phase Dry-Type Transformers

In power distribution systems, engineers and transformer designers often face a critical design decision when selecting transformer configurations: whether to use a three-phase transformer or a bank of three single-phase transformers. This paper presents a comparative analysis of a 750 kVA three-phase dry-type transformer versus a bank of three 250 kVA single-phase dry-type transformers. A three-phase transformer is connected in a Dd configuration to deliver the same total capacity as a bank of three single-phase transformers. The aim is to evaluate the operational implications of each approach under equivalent conditions. The experimental study covers electrical performance parameters such as efficiency, cost, load losses, and no-load losses. This study aims to assist transformer designers, researchers, and facility managers in making optimized decisions when selecting transformer configurations. It concludes that the optimal choice depends on the specific priorities of the application, whether favoring compact efficiency and cost or modular redundancy and logistical flexibility.