The star (Y) and delta (Δ) connection are two ways of connecting the windings of a three-phase electric motor or other device.



A star connection, also known as a wye connection, is made by connecting one end of each of the three windings to a central point, creating a Y-shaped connection. This configuration allows for a neutral point in the system and enables easier measurement of current.


A delta connection, also known as a mesh connection, is made by connecting the first end of one winding to the second end of the next winding, and so on, creating a triangular connection. This configuration does not have a neutral point, so it is not possible to measure current at a single point.



The choice between a star or delta connection depends on the specific application and the electrical system it is being used in. Star connections are generally used for lighting and power distribution systems where neutral point is required. While delta connections are used for large motors and high voltage systems where neutral is not required.

Star connection is less resistive than delta connections, it is easier to measure currents, and it has a neutral point that can be used for grounding. On the other hand, delta connections have a higher fault current rating and are more suited to high-power applications.