Column: Condition monitoring
Evidence-based asset management
Those charged with managing assets in any electric, gas, or water utility face similar challenges when trying to meet their respective companies’ obligations to the owners, operators, regulators, and the public affected by these assets. In this column, the focus will be on both liquid-immersed distribution and power transformers – key components in any network. With the onset of DER (Distributed Energy Resources) located at the grid edge, this will change the mode of system operation and will have an impact on managing the existing assets. Asset management decisions require accurate information to produce a risk-based prioritization of investments to determine the physical state of any asset. In other words, one needs to sort out the candidates that meet the business objectives for repair (major or minor), refurbishment, replacement or disposal. Some asset managers currently use a ‘Health Index’ for prioritising asset replacement. However, in many cases the index does not provide any indication of how quickly the worst transformers on the list need to be actioned, nor do many of them provide any indication of the most appropriate action needed i.e. replace, repair or refurbish. To increase the confidence in the data, asset managers should consider using a process called evidence-based asset management (EBAM).
Evidenced-based asset management (EBAM)
Definition: An evidence-based practice is any practice that relies on scientific evidence for guidance and decision-making. Practices that are not evidence-based may rely on tradition, intuition, or other unproven methods. The words “evidence-based” are commonly used to describe practices in medicine and healthcare industry, such as ‘evidence-based medicine’. However, the underlying principals do not change and can apply across most industries. The main concept being: when decisions are made, they are made based on the most up-to-date, solid and reliable scientific evidence. In this case, these are the decisions concerning the condition of individual assets.
Building confidence into a transformer condition assessment
The recently published CIGRE Technical Brochure 761 (TB 761), Condition Assessment of Power Transformers developed by CIGRE WG A2.49 aims to serve as a comprehensive guide to the development of transformer assessment indices for different purposes and discusses how to manage the issues listed above. It forms part of the key series of steps for transformer management outlined in CIGRE’s Guide for Transformer Maintenance 445 (TB 445). It serves not only as a reference guide to transformer failure modes and suitable condition assessment techniques to manage the asset, but as a comprehensive guide to developing indices for different purposes to improve transformer management outcomes.