Understanding 3 Phase Transformer Connections

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Three Phase Transformer Connections Phasor Diagrams Electrical Academia

A 3 phase transformer is a device used to transform electrical power from one form to another. It is used to convert the voltage or current of an alternating current (AC) electricity supply to another. This type of transformer is usually used in industrial settings or by electricians in homes and buildings.

The Basics of Connecting a 3 Phase Transformer

When connecting a three-phase transformer, it is important to ensure that the electrical wiring is done correctly. This includes connecting the phases in the correct order. The most common wiring arrangement for a 3 phase transformer is the Delta configuration. In this configuration, the three phases are wired together in a triangle, with each phase connected to one of the three terminals.

The next step is to connect the high voltage and low voltage windings to the primary and secondary sides of the transformer. The high voltage winding is usually connected to the primary side and the low voltage winding is connected to the secondary side. This allows the transformer to convert the voltage from the primary side to the secondary side. Finally, the neutral or common wire is connected to the ground or neutral terminal.

Diagrams of 3 Phase Transformer Connections

To make it easier to understand how a 3 phase transformer is connected, it is helpful to look at a diagram. These diagrams are available online, in books, and on the transformer itself. They show the connection of the three phases, the high and low voltage windings, and the neutral or common wire.

By looking at the diagram, you can easily identify the primary and secondary sides, and the connections between them. This will help you understand how the transformer works and make sure that it is connected correctly. It is also important to note the electrical safety codes and regulations for wiring three-phase transformers.


Connecting a 3 phase transformer correctly is important in order to ensure that it works properly. By understanding the basics of wiring and studying diagrams, you can make sure that the transformer is connected correctly. This will help your electrical project run safely and efficiently.