New technology recommended for Germany electricity

Edited by the Engineeringtalk editorial team Mar 6, 2007

EA Technology believes German electricity companies could benefit greatly from adopting the latest techniques for accurately monitoring the condition and safety of their medium voltage (MV) assets.

German electricity companies could benefit greatly from adopting the latest techniques for accurately monitoring the condition and safety of their medium voltage (MV) assets, based on the measurement of partial discharge activity, according to UK power engineering specialist EA Technology.

EA Technology's view is based on an independent report, sponsored by the RWE Group, which found that German engineers typically continue to rely on visual inspection, listening and their sense of smell to check whether problems are developing in MV assets, including switchgear and transformers.

"The RWE-sponsored report provides valuable insights into maintenance practices in the German industry and demonstrates that companies have much to gain from deploying the correct scientific instruments for assessing the condition of MV assets with accuracy", said EA Technology's Stephen Holmes.

"German engineers clearly realise that partial discharge activity indicates problems, in the form of visible and audible arcing, plus noticeable ozone emissions, but these are only likely to become apparent at the point where deterioration of assets is well advanced".

"They are unlikely to be equipped to determine with certainty when an asset is likely to fail or is in a dangerous condition".

"Meanwhile, most British electricity companies have equipped their engineers with new tools which enable them to measure the development of partial discharge activity at levels which are outside the audible and visible ranges, and to identify the location and magnitude of activity with precision".

"The ability to collect and interpret accurate information on asset condition is essential to decide when MV assets require maintenance interventions or replacement, because without it, engineers are effectively operating on guesswork".

"They may also be exposing themselves and colleagues to lethal dangers".

The RWE-sponsored report by electricity engineer Bastian Homburg, titled "Analyse und Auswahl von Messverfahren zur Zustandsbestimmung von Mittelspannungs-Stationen", included the results of trials on four instruments for monitoring the condition of MV assets: a thermographic camera, an ultrasonic listening device, an earth current monitor and EA Technology's UltraTEV partial discharge detector.

The UltraTEV was found to be by far the most useful tool for assessing asset condition, in terms of accuracy, objectivity, speed of use, sensitivity, flexibility, safety and value.

It was also the only instrument which effectively detected partial discharge activity internally as well as on the surface of assets.

The UltraTEV is the only handheld partial discharge instrument in the world to combine two sensor technologies, detecting both ultrasonic and transient earth voltage (TEV effects).

The report found it extremely easy to use, as it employs a simple "traffic light" display, showing green if an asset is working properly, amber when it requires further investigation and red when it needs immediate maintenance intervention and/or is dangerous to approach.

Trigger levels for each light are based on EA Technology's 40-year experience of studying patterns of deterioration in MV and HV assets and the report found they were set at exactly the correct thresholds, with no false indications of problems.

The report concludes that German electricity companies should become more familiar with the latest techniques for monitoring partial discharge activity scientifically, as represented by the UltraTEV.

By doing so, they will gain a much greater understanding of the actual condition of their MV assets, which will enable them to prioritise maintenance and plan asset replacements more intelligently.

Holmes added: "The British electricity industry long ago accepted that condition-based maintenance is essential for managing their assets more effectively and at lower cost than in the days when funding was more freely available".

"It is no longer acceptable in the UK to wait for assets to fail, then replace them".

"Given the increasing pressure on expenditure within the German industry, we believe it is inevitable that it will follow the same path".