
SWITZERLAND - The results confirmed that the transformer pressboard has a higher thermal class, which challenges the decades-old assumption relating to the thermal class of transformer pressboard as used in both power and distribution transformers.
Weidman has announced that in a recent study, they investigated the thermal aging performance of their Transformerboard, as well as the sealed tube aging test procedure itself. Weidmann stated that the tests were only conducted on their in-house manufactured transformer pressboards, which adhere to their own internal specification and quality standard. No other manufacturers’ materials were tested, and that they couldn’t comment on the performance of those materials.
According to Weidmann, in the 2011 edition of the IEEE C57.100 standard, a new sealed tube accelerated aging test procedure was introduced to determine the thermal class of solid and liquid insulation systems. The experimental work presented in the article investigated the effects of different test parameters on aging test results and data interpretation. The new findings on the dependence of the aging process on the ratio and type of materials in the system, as well as on the selected aging criteria, provide a better understanding of accelerated aging testing and the interpretation of aging data, along with practical recommendations for improvements to the test procedure.
In parallel, for the first time, the thermal index (and corresponding thermal class) of Weidmann’s transformer pressboards, as a component of the ‘industry-proven ‘insulation system together with thermally upgraded kraft paper and mineral oil, was investigated and defined based on the standard industry test. The results confirmed that the transformer pressboard has a higher thermal class, which challenges the decades-old assumption relating to the thermal class of transformer pressboard as used in both power and distribution transformers.
Source: Weidmann