General theory of the auto-transformer

The method of complex quantities lends itself admirably to the development of general theory of the auto-transformer. As worked out, in this instance, it is found desirable to maintain the actual voltage ratio instead of reducing values to an equivalent 1:1 basis. Examples are given of calculations by this method, and also comparison is made with calculated performance of the two-circuit transformer. Certain inherent peculiarities of the auto-transformer are pointed out, being due to the effects of internal resistance and reactance. Part II is an application of the theory to transformers without iron and a number of interesting conclusions are brought out.