Electricity and Electronics for Renewable Energy Technology

Appendix C: Special Transformers

C1.1 Zigzag Transformer

A zigzag transformer, alternatively known as an interconnected-star (or wye) transformer, is a three-phase special transformer for the purpose of creating a neutral point for grounding, where there is not such a point available. For example, in three-phase lines coming out of a delta connection, there is no neutral reference point. Also, in transformers where for a technical reason a delta connection is compulsory and for fault protection it becomes necessary to have a ground reference, a zigzag transformer can provide the neutral point.

In a zigzag transformer each phase has two identical windings wound in opposite directions to each other, similar to that in Figure 10.4. In other words, ...