Understanding Three-Phase Transformer Connections-1 — Lesson 2

This lesson covers the intricate details of 3 phase transformers and their connections. It delves into the importance of polarity and terminal markings in these transformers. The lesson explains the difference between star and delta connections, and how they impact the performance of the transformer. It also highlights the potential issues that can arise if these connections are not made correctly. For instance, the lesson demonstrates that even if the primary and secondary are connected in a star configuration, a balanced three-phase voltage may not be achieved if the correct dot polarity is not followed.

Video Highlights

01:22 - Discussion on star connection and its rating
10:12 - Explanation of the importance of correct polarity in transformer connections
18:55 - Explanation of star-star connection and its phase displacement
27:09 - Explanation of star-delta connection and its phase displacement
35:33 - Conclusion and summary of the lesson

Key Takeaways

• Polarity and terminal markings are crucial in 3 phase transformers.
• Star and Delta connections have different impacts on the transformer's performance.
• Incorrect connections can lead to unbalanced three-phase voltage.
• Even if the primary and secondary are connected in a star configuration, a balanced three-phase voltage may not be achieved if the correct dot polarity is not followed.
• In a delta connection, even if each coil becomes a seat of EMF, no circulating current will be present if the voltages are balanced and 120 degrees apart.