Separate Leakage Reactance of Transformer Windings

The paper discusses a method for determining the separate leakage reactances of transformer windings, originally suggested in 1921 by W. V. Lyon.2 The method is applicable only to three-phase banks of three identical transformers, and makes use of the third harmonic electromotive force and current which are introduced into the windings by the inherent magnetizing characteristics of the iron. Attempts made to determine the separate leakage reactances of a single transformer did not meet with success. The method may be used both with ``two-winding'' and ``multi-winding'' transformers. However, it is particularly convenient when the transformers have more than two windings. Laboratory tests have been made on small experimental, two-winding and three-winding transformers, and field tests on a bank of three-winding power transformers. The results in each case warrant the conclusion that the separate leakage reactances may be obtained with sufficient accuracy for engineering purposes.