Understanding Practical Transformers and Phasor Diagrams — Lesson 2

This lesson covers the concept of practical transformers, their working, and how to draw their phasor diagrams. It starts with a discussion on the practical transformer, its components, and how it differs from an ideal transformer. The lesson then delves into the concept of magnetizing current and how it affects the operation of a transformer. The instructor explains how to draw the phasor diagram of a transformer, taking into account the magnetizing current and winding resistances. The lesson concludes with a discussion on the equivalent circuit of a transformer, both from the primary and secondary side. For instance, if a transformer has a load power factor, the current drawn from the primary will be the sum of the magnetizing current and the reflected current.

Video Highlights

01:08 - Discussion on the concept of net MMS in the circuit and the role of supply voltage and frequency in deciding the flux in the core
04:06 - Explanation of the equivalent circuit referred to the primary side and the secondary side.
07:28 - Discussion on the incorporation of winding resistances into the practical transformer model
19:10 - Discussion on the drawing of the phasor diagram for the practical transformer model, highlighting the role of load power factor and the impact of winding resistances.
29:17 - Conclusion of the lecture, with a promise to bring other realities into the ideal transformer in the next class.

Key Takeaways

• A practical transformer differs from an ideal one due to the presence of winding resistances and magnetizing current.
• The magnetizing current in a transformer is finite and affects the operation of the transformer.
• The phasor diagram of a transformer helps in understanding the operation of the transformer, taking into account the magnetizing current and winding resistances.
• The equivalent circuit of a transformer can be viewed from both the primary and secondary side.
• The current drawn from the primary of a transformer is the sum of the magnetizing current and the reflected current.