In the context of electric power distribution systems, a "wye-wye" configuration typically refers to the connection of three-phase transformers. The wye-wye connection, also known as the "star-star" or "Y-Y" configuration, is a common method used to connect three-phase transformers. It is called "wye" because the transformer windings are connected in a Y-shaped configuration.
Here's how a transformer is connected in a wye-wye configuration:
Primary Side: On the primary side of each transformer, the three windings are connected in a Y-shaped arrangement. Each winding connects to one of the three phases of the primary power source. The common point where all three windings meet is called the "neutral" or "star point" (represented by the letter "N").
Secondary Side: On the secondary side of each transformer, similar Y-shaped windings are used. The secondary winding of each transformer is connected in a Y-configuration, and each end of the winding is connected to one of the three phases of the secondary load.
Neutral Connections: In a wye-wye configuration, the neutral points on both the primary and secondary sides are usually connected together. This means the neutral of the primary side is connected to the neutral of the secondary side.
Phase Rotation: It is essential to ensure that the phase rotation (sequence) is the same on both the primary and secondary sides. Typically, utilities maintain a consistent phase rotation in their power distribution systems.
The wye-wye configuration offers several advantages, including easy grounding of the neutral, good phase-to-neutral voltage regulation, and the ability to handle unbalanced loads effectively. However, one of the drawbacks is that it does not provide inherent phase shift capability, which might be needed in specific applications. For phase shifting, other configurations like the "delta-wye" or "wye-delta" may be used.