Clarifying concepts and gaining a deeper understanding of ideal transformers

摘要

Even in ideal transformers, the input and output powers are never exactly equal, thereby causing the familiar ratio between the primary and secondary currents, namely I-p:I-s = N-s:N-p, to be slightly incorrect. In this paper, we explain why this is so and derive the correct ratio, as well as clarifying the related prevailing concepts. We conclude that a theory of an ideal transformer without a magnetising current is deficient and self-contradictory. Further, methods to locate the two black (phase) dots in a transformer symbol are elucidated. This paper is suitable for those who are pursuing a deeper understanding on this subject after learning the basics from the literature.