This lecture provides an in-depth exploration of transformers, focusing on their fundamental principles and applications in electrical machines. It begins with an introduction to the basic elements of transformers, including the magnetic circuit and the concept of transformation ratios. The instructor discusses the differences between ideal and real transformers, emphasizing the significance of losses and efficiency. Key equations governing transformer operation are presented, along with equivalent circuit models. The lecture also covers the operation of single-phase and three-phase transformers, including coupling groups and special transformers. Practical examples illustrate how transformers are used in various applications, highlighting their importance in electrical systems. The instructor concludes with a summary of the key concepts and equations, reinforcing the understanding of transformer functionality and its critical role in electrical engineering.