Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 57 4 2025 06 22 Enhancing the Seismic Resilience of Aerial Substations: A Case Study of a Mid-Line Two-Pole 315 kVA Transformer Enhancing the Seismic Resilience of Aerial Substations: A Case Study of a Mid-Line Two-Pole 315 kVA Transformer 695 714 5767 10.22060/ceej.2025.23376.8154 FA Hamid Toopchi-Nezhad Department of Civil Engineering, Razi University, Kermanshah, Iran 0000-0001-8484-4603 Journal Article 2024 07 24 Experience from past earthquakes has shown that transformers installed on aerial utility poles are among the most vulnerable components in power distribution networks. Significant vibrations and rotations of transformers during seismic events can damage transformer accessories such as bushings, and compromise the connections of their mounting platforms, potentially leading to sliding or overturning of the transformer. In most existing aerial substations in Iran, one or both ends of the transformer platform are connected to the reinforced concrete poles using friction-based joints instead of standard bolted connections. This paper investigates the underlying reasons for the widespread use of frictional connections in conventional pole-mounted substations and evaluates the seismic behavior of a 315 kVA two-pole transformer installation located at mid-span of a distribution line. The main contribution of this study lies in diagnosing prevalent technical flaws in standard aerial substation connections nationwide and introducing a novel seismic retrofit strategy. The proposed retrofit method is founded on two key principles: simplicity and technical refinement. Simplicity ensures the solution avoids execution complexity and costly equipment, while technical refinement guarantees a coherent, well-balanced design with no mismatches or inconsistencies. Nonlinear time history analyses reveal that the seismic performance of the frictional platform-to-pole connections is inadequate, rendering the substation vulnerable under design-level earthquake scenarios. Subsequently, retrofit solutions are proposed to improve the resilience of the transformer platform connections. The seismic response of the retrofitted substation is then compared to its original, unstrengthen state. The proposed retrofit measures significantly enhance the performance level of the aerial substation by limiting transformer rotation to below 0.015 radians, thereby improving transformer stability under design-level seismic events. Experience from past earthquakes has shown that transformers installed on aerial utility poles are among the most vulnerable components in power distribution networks. Significant vibrations and rotations of transformers during seismic events can damage transformer accessories such as bushings, and compromise the connections of their mounting platforms, potentially leading to sliding or overturning of the transformer. In most existing aerial substations in Iran, one or both ends of the transformer platform are connected to the reinforced concrete poles using friction-based joints instead of standard bolted connections. This paper investigates the underlying reasons for the widespread use of frictional connections in conventional pole-mounted substations and evaluates the seismic behavior of a 315 kVA two-pole transformer installation located at mid-span of a distribution line. The main contribution of this study lies in diagnosing prevalent technical flaws in standard aerial substation connections nationwide and introducing a novel seismic retrofit strategy. The proposed retrofit method is founded on two key principles: simplicity and technical refinement. Simplicity ensures the solution avoids execution complexity and costly equipment, while technical refinement guarantees a coherent, well-balanced design with no mismatches or inconsistencies. Nonlinear time history analyses reveal that the seismic performance of the frictional platform-to-pole connections is inadequate, rendering the substation vulnerable under design-level earthquake scenarios. Subsequently, retrofit solutions are proposed to improve the resilience of the transformer platform connections. The seismic response of the retrofitted substation is then compared to its original, unstrengthen state. The proposed retrofit measures significantly enhance the performance level of the aerial substation by limiting transformer rotation to below 0.015 radians, thereby improving transformer stability under design-level seismic events. https://ceej.aut.ac.ir/article_5767_b8b12f949378552c21f28deff8ba8eb6.pdf