Unveiling Transformer Failures: Insights from Utilities Repaired Transformers and Their Revival

Abstract

Power transformer failures pose a significant challenge to power utilities, leading to service interruptions, costly repairs, and operational inefficiencies. In Maharashtra, the State Transmission Utility has observed a marked increase in transformer failures over recent years, negatively impacting service reliability and increasing operational costs. This paper investigates the root causes of these failures using Failure Mode and Effects Analysis (FMEA), supported by MATLAB-based modelling by collecting the comprehensive data related to transformer failures. The analysis focuses on identifying critical failure modes, assessing their occurrence rates, and evaluating their severity. Short circuit failures, identified as the most critical failure mode, are further analysed through factory inspections and substation visits to understand the operational and mechanical stresses imposed on transformers during faults. The paper also examines the effectiveness of current repair practices and operating procedures. Based on this comprehensive analysis, recommendations are made to improve transformer reliability by addressing key failure modes, enhancing repair protocols, and implementing operational changes to mitigate future failures. This dual approach provides a robust framework for reducing transformer failures and improving power system reliability to the utility systems.