Step down transformers of three phases, voltage of three primary winding down transformers to a lower voltage in the three windings of the secondary type. These are wounded by the three legs of the core of transformers. On each leg there is one secondary and one primary winding. These windings are connected by delta or WYE phases depend on the application.
Wiring of the three phase Step-down transformers consists three primary windings is connected to the side of high voltage and the three secondary winding is connected to the side of the low voltage. A double yoked shape is formed by the six windings bounded on the magnetic core.
There are three vertical legs connected at the bottom and top by two beams which are horizontal. Each leg of the double yoke has primary and secondary windings. High voltage of the primary winding have more turns than the turns in the low voltage of the secondary windings. Ration of the turn numbers of secondary to primary winding give the step down voltage of the step down transformers.
Each primary and secondary windings have two ends which is connected to the three phase to the side of low and high voltage. Without a ground connection, there is a winding connection of the end to end to form a triangle. This type of connection is called as the delta connection in which three phases are connected of the triangle through their corners. A WYE connection is also formed by connecting together to make a “Y” to ground.
There are four possible winding connections in each side of the step down transformers. These are connected to the three phases at the rated voltage. To project changes, there are certain options on the secondary side. Sometimes transformers have six ends of three windings on the terminals so that configuration of the winding can change according to the need. It can also be connected by the delta or WYE connections.