Understanding Efficiency in Electrical Transformers-2 — Lesson 5

This lesson covers the concept of efficiency in electrical transformers. It discusses how to estimate the efficiency of a transformer and the factors that influence it. The lesson explains the relationship between efficiency and degree of loading, and how maximum efficiency occurs at a certain value of loading. It also highlights the importance of power factor in determining efficiency. The lesson further explores different scenarios such as transformers operating at full load, transformers with fluctuating loads, and distribution transformers. It introduces the concept of energy efficiency or all-day efficiency, which is particularly relevant for distribution transformers. An illustrative example is provided using a 10kVA single-phase transformer to explain these concepts.

Video Highlights

00:14 - Introduction to the lecture on electrical machines and discussion on estimating the efficiency of the transformer.
07:53 - Explanation of the use of transformers in power systems and the importance of operating them at full load condition.
23:25 - Discussion on the concept of energy efficiency or all-day efficiency for distribution transformers.
25:56 - Discussion on the efficiency versus degree of loading curve at different power factors and the impact on maximum efficiency.

Key Takeaways

• Transformer efficiency is influenced by the degree of loading and the power factor.
• Maximum efficiency occurs at a certain value of loading, which can be determined by the ratio of core loss to copper loss at full load.
• For transformers operating continuously at full load, maximum efficiency should ideally occur at full load condition.
• For transformers with fluctuating loads, such as distribution transformers, the concept of energy efficiency or all-day efficiency is more relevant.
• Energy efficiency is calculated as the ratio of energy delivered to the load in a day to the energy input over the same period.