Winding configuration (delta, wye, zigzag, autotransformer, three-winding) is chosen based on system grounding requirements, voltage levels, fault currents, and harmonic performance. Utilities may require specific vector groups to manage phase shifts or parallel operation with existing units. Mechanical considerations, such as short-circuit withstand and ease of manufacturing, also play roles. The configuration affects impedance, zero-sequence behavior, and the ability to connect to particular network topologies in transmission or distribution systems.