Root Cause Analysis and Prevention of Unnecessary Outage for an Abnormally Noisy 220MVA 400kV Power Transformer using Comprehensive Condition Monitoring Framework

Being extremely critical components of power grids, power transformers' considerable capital cost, long and expensive repairs and more importantly, tremendous network outages and stoppages of production plants upon their probable failures highlight the importance of their condition monitoring and fault diagnosis programs. While it is important to prevent transformers from failures and to shut them down immediately in case of serious threats, their prominent role in the grid and hence in production plants necessitates minimization of unnecessary outages and shutdowns; from both technical and economical perspectives. This paper investigates an actual case study of a 220MVA 400kV power transformer with an abnormal nonstandard sound noise and elaborately decides whether to shut it down immediately in a very critical production condition. Visual inspections, dissolved gas analysis, frequency response analysis, thermal imaging together with the novel less frequently used transformer vibration and sound measurements are utilized in this comprehensive analysis.