Analysis and Short-circuit Test Investigation on Mechanical Stability of Power Transformer Winding

Abstract The deviation from checking the transformer's short-circuit capacity is challenging to control because of the difficulties in detecting critical stability through standard short-circuit tests or faults. To accurately evaluate the mechanical strength of power transformer winding, this paper proposes an obtaining radial buckling stress (ORBS) method for the inner windings based on the non-equivalent force characteristics of the winding disks at different height positions. Firstly, after designing a test transformer and calculating the critical buckling current based on traditional methods, 22 short-circuit tests are implemented by gradually increasing the short-circuit current. Additionally, various feature data representing excessive winding deformation are characterized, and the trans-former is disassembled, with the "step" deformation positions marked as the critical buckling points. Finally, the differences between different destabilization algorithms are analyzed by loading the maximum current into the simulation model and obtaining the critical buckling stress at the marked position. The results indicate that the critical conditions of mechanical stability of transformer winding can be investigated accurately through multiple destructive short-circuit tests in a limited tested model based on the ORBS method. Furthermore, the ORBS method can improve the design and verification of the ability to withstand the short circuit.