Impact of Tap Changer Configurations on Short-Circuit Inductance of a Transformer: An Analytical Approach

Voltage fluctuations within the power system necessitate the implementation of tap changers to adjust transformer winding turns, thereby regulating voltage levels according to load demands and mitigating voltage drops. This study examines on-load tap changers (OLTCs), which are crucial in facilitating voltage regulation and load management. Various methodologies for applying OLTCs in transformers are explored, with emphasis placed on the critical dependence of OLTC selection on the short-circuit impedance of transformers. It is noted that this dependency significantly affects both electrical and magnetic parameters, ultimately influencing the overall performance and efficiency of a power system. This paper provides an analytical examination of the operational mechanisms of different types of OLTCs, along with an evaluation of their impact on the electrical and magnetic characteristics of a 30 MVA transformer.