Sargı geometrisinin kısa devre durumunda dağıtım transformatörleri sargı kuvvetleri ve mekanik deformasyonlarına etkisinin incelenmesine katkılar

Current passing through transformer windings causes electromagnetic forces, which are proportional to the square of current. Extreme forces on transformer windings may cause damages although circuit breakers interrupt current in a short time period. The forces on windings also depend on the time instant when the short circuit takes place. However, the case that causes maximum force should be simulated to ensure the transformer withstands forces. It is known that irreversible deformations and displacements will reduce the durability of the transformer for the next short-circuit operation. In this study, a three-phase power transformer with same ratings is designed in three different winding geometries namely cylindrical, elliptical and square. For each design, worst-case analysis is performed under short circuit conditions. Force distribution is almost uniform on cylindrical design while it differs in different regions of elliptical and square windings. Force on narrow part of elliptical windings is less than the wide part, which is sharper. Similarly, forces obtained for flat parts of square design are less than those obtained for corner parts are. Additionally, it is observed that maximum forces on cylindrical windings are less than maximum forces on elliptical and square windings. Square windings are subjected to the highest forces. ANSYS software is utilized in order to simulate the mechanical deformation and stress on transformer windings under short circuit. Obtaining the results, it is observed that deformation and stress on cylindrical design is minimum while the deformation and stress on square design is maximum among three designs.