Understanding Auto Transformers and Winding Transformers-1 — Lesson 4

This lesson covers the comparison between auto transformers and two winding transformers. It explains how to transfer a certain amount of kVA from the primary source side to the load side at two fixed voltage levels using either a two winding transformer or an auto transformer. The lesson also discusses the advantages of using an auto transformer, such as less copper requirement and savings in copper. However, it also highlights the issues with auto transformers, such as the lack of isolation, which can be problematic in case of an open circuit fault. The lesson further explains when to use auto transformers and two winding transformers based on the voltage transformation ratio and the need for isolation. It also includes numerical examples to illustrate the concepts.

Video Highlights

00:46 - Comparison between auto transformers and two winding transformers
15:15 - Step down auto transformer example
16:28 - Ideal auto transformer example problem
29:07 - Shortcut to determine current distribution in coils

Key Takeaways

• Auto transformers require less copper compared to two winding transformers, leading to savings in copper.
• Auto transformers do not provide isolation, which can be problematic in case of an open circuit fault.
• Auto transformers are more suitable when the voltage transformation ratio is close to 1, as the savings in copper will be more substantial.
• Two winding transformers should be used when isolation is a must, especially when the load is critical.
• The choice between auto transformers and two winding transformers depends on the voltage transformation ratio and the need for isolation.