Y-Δ transform
![Δ and Y circuits with the labels which are used in this article.](/Images/godic/202502/21/Wye-delta-2.svg0952.png")
![Transformation of a bridge resistor network, using the Y-Δ transform to eliminate node D, yields an equivalent network that may readily be simplified further.](/Images/godic/202502/21/Wye-delta_bridge_simplification.svg0952.png")
![Transformation of a bridge resistor network, using the Δ-Y transform, also yields an equivalent network that may readily be simplified further.](/Images/godic/202502/21/Delta-wye_bridge_simplification.svg0953.png")
The Y-Δ transform, also written wye-delta and also known by many other names, 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 Δ. This circuit transformation theory was published by Arthur Edwin Kennelly in 1899. It is widely used in analysis of three-phase electric power circuits.