So I have been doing a lot of practice exams and it seems like I am still struggling with the basic three phase transformer circuit analysis type of questions but getting other complicated questions correct. Does anyone have a good reference or a link to online article where I can find equations and basic understanding of different types of three phase transformers and some examples to go along with it? Something as simple as converting delta source to wye source or analysis of wye grounded vs wye not grounded, broken delta transformer or grounded delta transformer and so on. Any suggestions on what has been working for you so far or what really got you to understand some of these concepts are also appreciated. Thanks!