Smart testing

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KEMA Laboratories
Smart Testing
Suddenly we have decided to approach problems in the smart way. Also at the recent CIGRE conference (the largest in the word on electrical power engineering) the word "smart" was buzzing all over the place.
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  • Keywords: KEMA Laboratories, Corporate energy users, Governments, Manufacturers, Utilities

After the European Technology Platform on “Future Electricity Grids” introduced itself as the “Smart Grid Platform”, the concept of the "smart grid" has gained world-wide acceptance as a technology concept of embedding distributed energy resources flexibly into the distribution system. In its wake a whole range of products and services are riding the wave. Smart green energy, smart buildings, smart green city, smart green cars, smart meters, suddenly pop-up in glossy brochures and flashy promotional videos of power utility companies showing futuristic city life with yourself as a movie star.

Can testing remain stupid?
Being in the shadow for the general public, testing is certainly not that manifest as the every day commodities to which the value "smart" is now added rapidly. However, its role in quality assurance in electricity supply and in a wider sense as an increase of service quality all over is out of the question. Test laboratories in the world are dealing with an increased awareness of reliability, but also of liability, personnel safety, security and vulnerability of vital systems.

Electrical equipment testing is traditionally separated in three categories:

  1. Type testing: this is the most commercial one, because its aim is to obtain a certificate being the key to the market. Test-objects and test procedures are solidly anchored in international standards and equipment designers hold on to standardized requirements as their targets.
  2. Acceptance testing: these are tests beyond the standards, resulting from non-standardized stresses or operation conditions of equipment users. There is less and less recognition for this category of testing, on the one hand because of a loss of technical expertise at the users' side on how their system may differ from a "standard" one and a strong desire for standardization on the other.
  3. Development testing: this is the most technical one, since during the development process equipment designers derive relevant data regarding the behaviour of their proto-types under realistic stresses. 
It is especially the third category where smart testing is introduced. For type- and acceptance testing, the pass/fail word is the only relevant issue. This digital approach is commonly accepted, but much more can be learned from tests when "intelligence" is added and this is why smart testing deserves its name.

In addition to the classical pass/fail result, dedicated measurements give additional information on the behaviour of equipment under the relevant stresses.< By building up experience, test laboratories can analyze these data, allowing conclusions e.g. on margins with respect to test result. If an object passes the test, it may do so with a large margin, in which case the design is not cost effective. If it fails, it is very interesting to know how close the object was to pass and why.

KEMA Laboratories developed the "current zero technology", that does exactly what is described above for high-voltage circuit breakers. By looking into the critical ("current zero") region of the short-circuit interruption process, relevant performance indicators are derived that assist development engineers. After more than one thousand of such "smart tests", the method has demonstrated its maturity. Apart from application in our own labs, the technology has found its way to several development laboratories.

Also other examples are developed. One method was developed with the University of Darmstadt, Germany of measuring the extremely small quantum mechanical electron field emission current that flows in vacuum circuit breakers after interruption. Proper interpretation gives a clue to the dielectric strength of vacuum interrupter after “maltreating” its contact system with all kinds of switching arcs.

Few other technologies are under development that all have refined measurement and data processing as its common denominator. They rightly deserve the term "smart" since they combine the brute force of kilo Volts and kilo Amperes with state-of-the-art development in data acquisition, analysis and theory of physical processes.

This is not the only lesson that can be learned from the management of high-voltage grids, that were already smart long before the term was coined to utility use. Beware of the first byword my dictionary gives for the word "smart": "neat and well-dressed; fashionable". I like the second byword better: "clever and quick in thought and action". Let's go for that one.

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