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Ageing assessment of transformer paper insulation is commonly conducted through measurement of different chemical indicators in oil such as carbon oxide gases and furanic compounds [1]. Apart from these conventional paper ageing indicators, recent research success has shown that methanol and ethanol in transformers can also be used to indicate the degradation of transformer paper insulation [2].
Insulating oils are widely used in power transformers. The oil insulation degrades under multiple stresses during the transformer operation, which affects the insulation integrity and consequently could cause transformer failures. DC resistivity is one of the dielectric parameters of insulating oil for assessing transformer insulation conditions. This paper presents results of DC resistivity measurements...
Aging of transformer paper insulation is commonly investigated through indirect measurements conducted in the oil, e.g. furanic compounds. In addition to the conventional indicators, recent investigations showed that alcohols like methanol and ethanol in oil could be used as paper aging indicators. This paper focuses on the applicability of these new paper aging indicators in a novel, gas-to-liquid...
Ageing assessment of transformer paper insulation is important due to its irreversible ageing nature. Due to the poor accessibility of the paper samples in field transformers, large efforts were made to seek for chemical parameters in oil to indicate paper ageing, e.g. furanic compounds and dissolved carbon oxides. In recent years, alternative parameters including methanol and ethanol in oil were...
The high level of reliability experienced by power transformers has led to the situation that a large number of aged units are still operating in the power systems. However, uncertainty on how transformers behave when aged causes concerns over the existence of possible hidden failure modes, which have yet to be revealed by failure data. In order to establish whether aged transformers are able to maintain...
Power transformers are considered to be one of the most critical components of a power system. Due to ageing the majority of transformer populations are at or approaching their anticipated design lives, causing growing concerns over possible consequential impacts to system reliability. It is essential for utilities to maintain high levels of system reliability and ensure the continued cost-effectiveness...
Oil tests are crucial for condition assessment of transformers. Moisture, acidity, breakdown voltage, dissolved gas analysis and furans analysis are common oil tests carried out by utilities. IEC 60422 and IEC 60599 have specified some limit values for detecting any abnormalities based on oil tests. However, these limit values might not be suitable for all transformers at different ages or under different...
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