Weidmann Webinar: Accelerated Aging Test – A Determination of Transformerboard Thermal Class

Webinar Overview

The reliability of liquid-immersed transformers during long-term operation depends largely on using transformer insulation materials capable of withstanding the expected thermal, electrical, and mechanical stresses. The insulation system is a combination of solid insulation materials and an insulating liquid. These components interact with each other, and therefore, thermal performance can only be based on testing all the components.

In this webinar, we examine the sealed tube accelerated aging test (STAAT) procedure and methodology for evaluating the thermal index (TI) of liquid-immersed transformer insulation systems. Our studies investigate the effects of different test parameters on the aging test results and data interpretation. The dependence of the aging process on the type of materials in the system and the ratio between them, as well as on the selected aging criteria. This background provides a better understanding of the accelerated aging test and interpretation of the data, along with practical recommendations for the improvement of the test procedure.

Also tested in this experimental work are the thermal index and resulting thermal class of Transformerboard, and, for the first time, these tests confirm that Transformerboard’s thermal class is at least 120°C in both power and distribution transformers when combined with thermally upgraded Kraft paper and mineral oil.