Three Phase Transformers

Three-phase transformers serve as the "backbone hub" of power systems. Specifically designed for three-phase alternating current (AC), they act as the "main force" in power generation, transmission, and distribution links. They can synchronously perform three-phase voltage transformation, providing crucial support for large-capacity electrical energy transmission. Typically, these transformers adopt a three-phase common iron core structure (primarily the three-phase three-limb type) and three sets of primary and secondary coils, supporting multiple wiring configurations such as star (Y) and delta (Δ) (e.g., Dyn11, Yyn0) to meet the phase and grounding requirements of different power grids. Medium and large-capacity transformers mostly feature an oil-immersed design and are equipped with protective devices like gas relays and pressure relief valves, while dry-type structures are often used for small-capacity or special application scenarios. In terms of performance, three-phase transformers offer advantages including large rated capacity (ranging from tens of kVA to hundreds of MVA), high efficiency (usually between 95% and 99.5%), and low cost per unit capacity; however, it is necessary to maintain three-phase load balance to avoid additional losses and performance degradation. Their main applications include step-up transmission in power plants (e.g., 10.5kV→220kV), multi-stage voltage reduction in substations (e.g., 220kV→10kV→0.4kV), as well as power supply for industrial high-power equipment (such as motors and compressors) and large-scale public facilities (such as airports and high-speed railway stations).