Basic principles of DGA – Part I
DGA is a multidisciplinary and complex field, yet it is one of the most informative diagnostics tools for power transformers available nowadays.
byMarius GRISARU
Introduction
The importance of dissolved gas analysis (DGA) for transformer maintenance is, of course, very well known and already appreciated by the whole industry and the of Transformers Magazine readers.
The three previous articles [1 – 3] describe in detail the development of DGA through the ages and some future scenarios. Also, they described how DGA obtained the role of a first and most crucial test for general transformer health. As a by-product of those facts and knowledge, the readers may study some basic principles related to transformer design, materials, exploitation, and the DGA technique.
The knowledge presented and described in the three articles was based on chemical principles, electrical principle, and 30 years of experience performing that test along with all the related activities from sampling to post-mortem inspections and, of course, brainstorming at DGA Working Groups. The knowledge has been presented from a user’s perspective and contains field, laboratory, and active expert’s interaction with minimum commercial bias.
There are several layers of understanding and mastering the knowledge that can also be applied to DGA expertise
However, acquiring knowledge is definitely not enough for anybody to use and apply for an organisation’s or their personal benefit. This topic has been well known in education science as Bloom’s taxonomy introduced in 1956 and revised in 2001. It is one of the most well-known frameworks for classifying educational goals, objectives, and standards, and it is practically synonymous with the cognitive domain.
From the pyramid, Fig. 1, adapted to DGA education target, the readers may follow their progress in comprehending the DGA related knowledge. Most existent offline and online training courses and webinars are limited to acquiring and remembering the knowledge without offering the attendee the self-capability to apply it by a real experiment. Understanding the already solved cases is not sufficient to be able to confront new situations with a transformer with new technologies and materials.
The real-life situation is that the attendee will try to apply the same principles in his / her unresolved cases, and in most cases at the beginning, he / she will misuse them. Of course, if the engineer is perseverant and the transformer owner has enough patience, after several cases and having gained enough experience, the fresh engineer will be capable of becoming an experienced DGA operator. Proper education may significantly reduce the cost of knowledge gained by experience.
In contrast to the previous articles, this one is more oriented to explain learning, understanding, knowledge, and beyond. It intends to explain to the young and middle-aged generation the difference of being able to do things by themselves compared to using an external advisor or using outsourced diagnostics. The pros and cons of outsourcing the diagnosis system will be intensively explained. As a preview, it can be stated that using an international standard or guides and models is the most plausible way to attribute a transformer the condition to a statistical value of concept that may not match your specific equipment.
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