High Quality Content by WIKIPEDIA articles! The Y- transform, also written Y-delta, Wye-delta, Kennelly s delta-star transformation, star-mesh transformation, T- or T-pi transform, is a mathematical technique to simplify the analysis of an electrical network. The name derives from the shapes of the circuit diagrams, which look respectively like the letter Y and the Greek capital letter . In the United Kingdom, the wye diagram is sometimes known as a star. This circuit transformation theory was published by Arthur Edwin Kennelly in 1899.