Is it true that all three-phase transformer banks can have only a single phase displacement?

The statement that all three-phase transformer banks can have only a single phase displacement is false. In three-phase systems, transformer banks can be designed to create various phase displacements, and they can be configured in different ways depending on the application.

One common configuration is the Delta-Wye (Δ-Y) connection, where one side is in a delta configuration and the other in a wye configuration, resulting in a specific phase shift of 30 degrees. There are also other configurations, such as Wye-Delta (Y-Δ), which can produce different phase relationships. In addition, specialized transformer configurations can achieve other phase displacements—such as the 12-pulse transformer bank, which is often used in harmonic mitigation applications.

Therefore, the capability of three-phase transformer banks to have a single phase displacement is not a limitation; instead, they can be designed for various phase relationships based on the needs of the electrical system. This flexibility allows for tailored solutions in a wide range of applications, demonstrating that the assertion in the question is indeed false.