Benefits and limits of advanced methods used for transformer diagnostics

Large power transformers belong to the most expensive and strategically important components of any power generation and transmission system. Their reliability is of key importance for the availability and profitable operation of such systems. A serious failure of a large power transformer due to insulation breakdown can generate substantial costs for transport to the factory, repair and financial losses due to power outage. Therefore, utilities have a clear incentive to assess the actual condition of strategically important transformers, with the aim to minimize the risk of failures and to avoid forced outages. Special attention in this respect is given to large power station step-up transformers, large substation transformers or any large autotransformers (phase shifter) in a HV transmission system.