Although transformers are regarded as highly dependable equipment, the world’s current transformer fleet is quite old. The average age for those in industrial plants is 30 years, and 40 years for those used by utilities. While aging transformers are generally not “ticking time bombs,” their failure rates as well as their replacement and repair costs are steadily – albeit slowly – increasing. 4 shows the development of the failure rate of transformers installed in industrial plants (dark orange), generation plants (light orange) and transmission networks (gray). The risk development curves are steeper for industrial and power generation plants as the transformers in these installations tend to be used more intensively. While age alone does not increase the risk of unexpected failures, it generally is an indication of this risk. Risk of failure is heightened by other factors, including type of application and the tendency to load transformers to their maximum to meet the economic needs of the deregulated environment and competitive markets.
5 shows the investment peak in the 1960s and 70s for many companies in Europe and the United States. The cost burden when replacing aging equipment has forced many companies to keep transformers operating beyond their recommended life span in order to smooth the investment peak. This is only possible by optimizing the maintenance of the transformers and by implementing measures that extend their use.
At the same time, financial constraints demand an increased return on investment under reduced maintenance budgets and spending. The maintenance budgets are under increased pressure due to liberalization and deregulation, which have created a more finance-based focus. As a result, operators can no longer follow a simple time-based maintenance strategy that mitigates risks by doing everything, every year, for all transformers. Instead, they must implement a more sophisticated condition-based maintenance strategy: doing more maintenance for high-risk transformers than for low-risk transformers.1 This requires reliable information about the status of the transformers.
Operational managers require special tools to support their strategic and day-to-day decisions, which address the above challenges and result in the right maintenance actions at the right time. Here, a clear trend has emerged: Managers are moving from using time-based maintenance to implementing condition-based maintenance, where decisions are no longer driven by an average timeframe defined by past experience and observations, but instead take into account the actual condition of the equipment and the level of reliability required to fulfill its function. TrafoAsset Management supports this trend by focusing on three elements: analysis, risk assessment, and planning of maintenance actions based on asset management scenarios 6.