1. Mechanical Faults in Oil‐Immersed Power Transformers with Disc‐Type Windings Due to External Short Circuit.
- Author
-
Miyazaki, Satoru, Mizutani, Yoshinobu, and Ichikawa, Michiharu
- Subjects
POWER transformers ,SHORT circuits ,AXIAL stresses ,ELECTROMAGNETIC forces - Abstract
This study investigated mechanical faults in oil‐immersed power transformers with disc‐type windings. Short‐circuit tests were conducted on eight aged removed transformers. Before the short‐circuit tests, accelerated aging tests were conducted on all the transformers to discuss the life limit of transformers. Six out of eight transformers experienced the internal ground faults. Although the radial electromagnetic force and the tolerance of the insulation paper against it have been mainly focused in discussing the life of the power transformers, the ground faults were triggered by the crush of the pressboard by the axial electromagnetic force. The axial compressive stress applied to the pressboards varies from the transformer to the transformer, depending on the design of the windings. The transformer, whose axial compressive stress was relatively lower, passed the short‐circuit test. However, even for the similar deterioration degree of the pressboard, the transformer, whose axial compressive stress was relatively higher, experienced the ground fault. These results indicate that the axial compressive stress during an external short circuit and deterioration of the pressboard are critical factors that determine the life of transformers with disc‐type windings. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF