Ferroresonance Analysis of Particular Iron Core Transformers

The paper quantitatively investigates the ferroresonance phenomenon for a specific class of single-phase and small power transformers. These low-voltage devices that usually exhibit an E+I iron-core shape geometry, are to be commonly found in actual electric and electronic installations. Their operation under no- or light load conditions in circuits that also include capacitive elements, favors the ferroresonance occurrence, which is usually initiated by a switching process. Thus, adopting a suitable magnetization description of the laminated transformer core, a time domain analysis is conducted by numerically solving the nonlinear and nonautonomous differential equations system that models the transients. Hence, the transformer current and voltage time variations are predicted and critically examined by modern investigation tools, specific to nonlinear dynamic systems such a ferroresonant circuit - harmonic analyses, 3D phase portrait and Poincaré map representations.