Understanding Electrical Machines: Transformers and Phase Conversion — Lesson 1

This lesson covers the intricate details of electrical machines, focusing on three-phase transformers and phase conversion. It explains the different connections of three-phase transformers, including star, zig zag, and delta connections. The lesson also discusses the concept of phase conversion, particularly the Scott connection, which converts a three-phase balanced voltage to a two-phase balanced voltage. The lesson further elaborates on the application of two-phase induction motors in control systems and other applications. It also explains how to convert a three-phase supply to a balanced two-phase supply voltage system using the Scott connection.

Video Highlights

00:32 - Explanation of when to select what connections, such as Star DD star or zig zag.
04:40 -Explanation of how to use two single-phase transformers for three-phase to two-phase conversion.
10:09 - Discussion on how to calculate the induced voltage in the secondary of the transformer.
21:34 - Explanation of how to create a balanced two-phase voltage using the Scott connection.
28:24 - Discussion on how to estimate the current drawn from the supply when a balanced two-phase load is connected.
33:17 - Explanation of how to balance the MMF of the secondary and primary for the transformer.

Key Takeaways

• Three-phase transformers have different connections, including star, zig zag, and delta, each with its own specific use cases.
• Phase conversion, specifically through the Scott connection, allows the conversion of a three-phase balanced voltage to a two-phase balanced voltage.
• Two-phase induction motors, which require a two-phase supply, are used in control systems and other applications.
• The Scott connection uses two single-phase transformers to convert a three-phase supply to a balanced two-phase supply voltage system.
• The voltage per turn of a transformer is a crucial concept in understanding the operation of transformers.