Electricity powers the world and is an
indispensable product for humanity,
almost like water and food. This
energy category needs two types of
materials which make it feasible -
electrical conductors and electrical
insulators. In practice, no one can
afford to use ideal conductors and
insulations matrixes. Accordingly, the
industry has to compromise with the
best available materials at acceptable
prices. Power transformers, like any
other electrical device, have to contain
these two types of materials. The most
Future brings some changes to DGA. It is expected that offline DGA in standard laboratories will gradually disappear as a routine test and transformers without online DGA will be tested by using simple portable devices. The online sensors will be monitored from a central control room with a sophisticated artificial intelligence in an effort to predict failures.
With time, the size of the transformer increased exponentially both in power andvoltage. Although huge improvements have been made regarding the magnetic core and the decrease of core losses, a
transformer is now producing much more heat due to the design optimization and size reduction. Heat reduces the insulating
properties of the insulating matrix, reducing the conducting properties and accelerating all chemical reactions including ageing and corrosion.
The stresses from the insulation materials increase gradually. In the last century, th...
There is a large number of national and international standards covering various aspects of transformer insulating fluids such as specifications, sampling techniques, testing procedures, maintenance, diagnostics, and so on. The present paper summarises available standards and
technical brochures related to the above aspects of the insulating fluid for an immediate reference to the user.
For good transformer condition assessment it is necessary to determine the condition of
insulating materials, both liquid and solid. Transformer is reliable for as long as its insulation system
resists deterioration. Therefore, thermal and oxidation stability are important characteristics of transformer
oil. It is a measure of oil resistance for decomposition by the influence of oxygen and temperature. Oils
with good thermal and oxidation stability retain their characteristics regardless the thermal stress.
Because of environmental and saf...
Dissolved gas analysis is a common technique in the supervision and maintenance of transformers. It can give hints on defects and faults in oil-immersed transformers by determining and quantifying the gases arising due to the thermal or electrical stress. Different algorithms for the assessment of transformers, which utilize data obtained from dissolved gas analysis, have been published so far. However, only few investigations exist that deal with the influence of the oil´s composition on the oil´s tendency of releasing gases. This research stu...
Dissolved gas analysis is a common technique in the supervision and maintenance of transformers. It can give hints on defects and faults in oil-immersed transformers by determining and quantifying gases arising due to thermal or electrical stress. Different algorithms for the assessment of transformers, which deploy data obtained from dissolved gas analysis, have been published so far. However, only few investigations exist that deal with the influence of the oil’s chemical composition towards the oil’s tendency of releasing gases. This researc...
The life of a transformer is inherently linked to the fundamental role of insulating oils to dissipate heat and protect the transformer’s solid insulation.
Developments in refining technology means that not all mineral oils are equal, and isoparaffinic oils in particular can offer enhanced oxidative stability, lower viscosity in colder temperatures, and superior heat transfer which results in improved reliability and utility for transformer operators.
The importance and cost of transformers is described and stressed in all the literature. Transformers are one of the most important and vital links in the electricity supply chain. Despite the very high cost related to transformer failures, the tests and diagnoses of the equipment itself, the transformer owner or a person responsible for its proper operation is faced with many diagnostic approaches and most of them are either inaccurate or unnecessary and irrelevant to individual case. Of course the lack of specialists in transformer diagnoses...
Transformer pits are conventionally filled with rocks in order to achieve passive fire safety in the event of an oil leak from the transformer. Other solutions also exist but there is no well defined test method that allows an assessment of the fire performance. In this brief article, such a test is presented together with test results for an alternative system where profile planks are used instead of rocks.