Analysis on Magnetic Characteristics of Three-Phase Core-Type Transformers [Part II: Non-Linear Solutions and Experimental Results for R3-Type Core]

This paper deals with the magnetic characteristics (the flux distributions, core losses, etc.) of threephase core-type transformers with double-layer. In the preceding report, only linear solutions have been given. In this paper, also non-linear solutions are discussed. Therefore, the flux waves of each magnetic path are distorted and contain various harmonics. When core losses are calculated, the hysteresis losses of minor loops are taken account. The results of analysis are compared with those of experiments. It is concluded that the principal cause for increasing core losses of this type core is the eddy current loss produced by harmonic fluxes. The flux distributions and the core losses depend on the shapes of the magnetization curve and the core-loss curve, that is, on the quality of the materials.