Oil Diagnostics- keep your assets healthy! | EA Technology
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Oil Diagnostics- keep your assets healthy!

  • 14 February 2017

  • EA Technology


Do you have electrical assets with an unknown asset condition, a need to manage, plan and execute effective maintenance, or ensure safety and reliability of a network whilst reducing costs? ………Oil Diagnostics is your answer!

Oil Diagnostics is a low cost and robust mechanism, which allows effective asset management of transformers and switchgear driven by asset condition. It can be used to give piece of mind in identifying which assets might need attention and which do not, ultimately saving money in the long run through targeted maintenance and averting costly replacements. It is used by companies across the globe to manage their fleets of transformers, switchgear and tap changers. EA Technology has been at the forefront of oil analysis in power applications for several decades.


It is well understood that the oil in a transformer and switchgear can tell a powerful story as to the condition or health of an electrical asset. Knowing where to look, and what to look for is key. There is a wide variety of analysis techniques available to choose from – at times this can be a minefield and selection headache!

Carrying out the following Oil Diagnostics on your transformer fleets gives you the required information to make those effective maintenance decisions:

Oil Quality – Moisture, Acidity & Breakdown Voltage

Measuring moisture, acidity, and breakdown voltage strength (solid contamination) of the oil gives a good indication of the overall condition of the oil and internal components. The quality of the oil is also critical in preventing premature ageing of the transformer and extending its service life.

Dissolved Gas Analysis (DGA)

The essential purpose of dissolved gas analysis is to detect gases generated due to thermal degradation of insulation components within the transformer. In particular, the aim of gas analysis is to provide prior warning of a developing thermal fault i.e. local overheating, discharge activity or arcing within the transformer.

Furfuraldehyde Analysis (Paper insulation assessment)

Furfuraldehyde analysis gives an accurate indication of the condition of paper insulation – the critical part of your transformers. The furfuraldehyde content is correlated to the degree of polymerisation of the paper. When furfuraldehyde levels reach specific values, we know that the insulation has effectively broken down, reducing its strength and significantly increasing the probability of failure.


These three tests suites give you the required information to understand the condition of the units and give you the platform to build up a streamline and effective asset management regime.

For the most effective asset management strategies it is best to assess the individual transformers as part of a population / site as a whole. Carrying out a Health Index Assessment allows the individual units to be assessed and identifies those units which could benefit from life extension maintenance or are in need of replacement.

The oil analysis provides a very good understanding of the internal condition of a transformer, including the condition of specific components. The oil analysis results are used in combination with relevant background information to create a Health Index for the asset, expressed as a numerical value on a scale (commonly 1 – 10) from which a Probability of Failure (PoF) and estimated end of life are determined. In addition, the future performance and condition can be evaluated. This is particularly valuable for prioritising the maintenance and replacement of multiple assets and is the foundation of asset investment management, such as Condition Based Risk Management (CBRM) or Great Britain’s Common Network Asset Index Methodology for regulatory reporting.

What does a good Health Index Assessment include?

A good health Index should include:

  • The oil results from the Oil Quality, DGA and Furfuraldehyde – anything beyond this is costlier and is a bonus but not necessarily required
  • Historical oil tests are also important in understanding underlying trends
  • Unit details (e.g. age, type ID’s, etc.)
  • Loading information: current & historical
  • Visual assessment survey information (e.g. rust, corrosion and leaks)
  • Previous fault information
  • Environmental information (e.g. location and pollution effects)

All of this information plays a part in understanding the overall health of the assets and allows for future plans based on the asset condition.
For those companies who have multiple sites e.g. across the UK, or even around the globe, assessing the units on a site by site basis is a very powerful tool. It can be used to understand the maintenance requirements across the whole of the company’s assets, allowing focussed and targeted interventions on individual sites and transformers at the same time.

Oil Diagnostics & Health Index Assessment is equally applicable to switchgear and tap changers and the results can be coupled with assessment work such as Partial Discharge surveys to build a robust health assessment of the asset population.

If you are responsible for the management of fleets of assets, then spending your budget on Oil Diagnostics and Health Index Assessment is a safe bet. It will give you the tools you need to deliver for a quick precise and very cost effective condition based asset management programme.

Simply put – spending money on Oil Diagnostics and Health Index Assessment will save on costly unrequired maintenance, putting money in your company’s pocket whilst maintaining a security of supply!

Contact EA Technology today to get started with the industry leader in oil diagnostics, call us on +44 (0) 151 339 2313.