Understanding Equivalent Circuits of Transformers-2 — Lesson 9

This lesson covers the concept of transformer equivalent circuits, including the exact and approximate equivalent circuits. It explains how to draw the phasor diagram for these circuits and how to simplify them. The lesson also discusses the concept of no-load condition and how it affects the equivalent circuit. It further explains how to calculate the equivalent resistance and reactance, and how to refer them to the primary or secondary winding. The lesson concludes with a discussion on how to determine the equivalent circuit parameters through open circuit and short circuit tests.

Video Highlights

01:10 - Discussion on the advantages of looking at the transformer equivalent circuit in terms of its approximate representation.
04:14 - Explanation of the phasor diagram drawing process
18:37 - Discussion on the concept of no load current of a transformer.
37:55 - Discussion on the concept of copper loss and cold loss in a transformer.
39:54 - Conclusion of the lecture and a preview of the next class.

Key Takeaways

• The transformer equivalent circuit can be represented in two ways: exact and approximate.
• The exact equivalent circuit includes all the parameters of the transformer, while the approximate equivalent circuit simplifies the circuit by assuming no current through the winding under no-load condition.
• The equivalent resistance and reactance can be calculated and referred to the primary or secondary winding.
• The equivalent circuit parameters can be determined through open circuit and short circuit tests. The open circuit test helps to calculate the core loss resistance and magnetizing reactance, while the short circuit test helps to calculate the winding resistance and leakage reactance.