Megger Transformer Intelligence Centre

The continuous escalation in energy demand does not parallel the pace of energy infrastructure development. Consequently, the necessity for alternatives beyond mere repair and replacement of critical equipment within the power grid is a critical consideration for asset managers and strategy planners striving for optimized equipment utilization.

In power transformers, the cellulosic paper employed in insulation systems is an organic polymer, and its aging (degradation) is an irreversible process. The end-of-life of a transformer is characterized by the estimated degree of polymerization (DP) of the paper. When the DP-value approaches two hundred (200), the paper insulation is deemed to be at or nearing its end of life.

Transformer testing, monitoring, and diagnostics have advanced significantly over the past decades, transitioning maintenance operations from time-based to condition-based and risk-based maintenance. Considering this transition, the decision-making process involves a comprehensive technical analysis based on field testing data, integrated with financial rules and economic analysis, to formulate and implement an effective transformer life extension strategy.

As delineated in CIGRE TB 887, “life extension is defined as a series of major interventions on a transformer, beyond “normal” maintenance, and repair, to rectify its issues, restore its condition, and defer a predicted end of functional, economic, or reliable life. This approach is applicable to, but not limited to, aged transformers with or without defects or faults, whether functional or failed.”

The methods of life extension range from oil treatment processes, active part drying processes and re-clamping, restoration of sealings, rust treatment, change and upgrade of components such as bushings, tap-changer, internal connections, cooling, oil preservation system, accessories, and refilling with alternative liquids up to complete refurbishment including the replacement of the windings.

MTIC is a software solution available today to assess the condition of a transformer and a fleet of transformers, covering fundamental and advanced diagnostics. It helps asset managers and operations staff determine specific asset management actions derived from reliable testing data, expert diagnostics, including operational constraints, expected levels of reliability, and risks.

A comprehensive assessment of a power transformer involves extensive electrical and dielectric testing, along with the analysis of relevant data such as operational and maintenance history, including commissioning data. 

This information later evaluated by experts based on pertinent standards and specialized knowledge. In the field, asset managers often oversee a large fleet of transformers and face the challenge of identifying those requiring immediate attention.  

The effectiveness of condition assessment is related to the understanding of transformer failure modes. Good understanding of transformer failure modes allows for better identification of defective components and sub-components in the transformer, which is the primary objective of condition assessment. Accurate condition assessment enables appropriate responses.

Screen the fleet before diving into deep waters of data. This provides a clear visualization of transformers with a higher risk of failure, facilitating further testing and assessment before making major asset management decisions such as repair, refurbishment, or replacement.

Transformer operators increasingly demand more intelligence and usability in programs that support human decision-making. In this regard, MTIC features intelligent analysis using Computational Intelligence (CI) and data storage, serving as a direct source of information for maintenance and operations staff, and asset managers. Transformers in critical condition benefit from the expert analysis developed in MTIC. Operations staff act upon bad or suspected erroneous test results or extreme observations. This initiative-taking approach identifies and diagnoses active deficiencies in power transformers, providing asset owners with reliable insights into the true and immediate condition of a transformer or a fleet of transformers. 

The answer is Asset Performance Management; the ability to decide not just which assets must be maintained in a shorter time period, but which assets can be maintained over a much longer time period without significant increased risk of failure. 

APM gives us the ability to move from antiquated Time-Based Maintenance strategies to Condition or even Condition/Risk Based strategies, allowing us to spend our O&M dollar where it is needed most.