Understanding Electrical Machines and Transformers — Lesson 1

This lesson covers the intricate details of electrical machines, focusing on transformers. It begins with a discussion on the concept of bolt per turn in transformers with multiple coils. The lesson then delves into the calculation of primary current in transformers with two secondaries. It further explains the concept of reflected components in currents and how to calculate them. The lesson also introduces the concept of power balance in AC circuits and how it simplifies the calculation of currents in transformers. Towards the end, the lesson discusses the realities of a practical transformer, such as finite magnetizing current, and how to model these realities in an ideal transformer.

Video Highlights

01:15 - Calculation of voltage per turn in a transformer
06:37 - Discussion on the concept of complex power delivered by a source
20:20 - Introduction to the concept of a practical transformer
29:23 - Explanation of how to model a practical transformer with a finite magnetizing current
33:58 - Discussion on how to calculate the current drawn from the supply in a practical transformer
36:24 - Conclusion of the lecture and introduction to the next lecture

Key Takeaways

• In transformers with multiple coils, the bolt pattern is a useful concept.
• The primary current in transformers with two secondaries can be calculated using the concept of reflected components in currents
• Power balance in AC circuits simplifies the calculation of currents in transformers.
• Practical transformers have realities such as finite magnetizing current, which can be modeled in an ideal transformer.
• The modeling of practical realities in an ideal transformer helps in understanding the behavior of practical transformers.