Handbook of Case Histories in Failure Analysis
Failure Analysis of Transformer Brackets
Six transformer brackets failed in service, sending a group of three pole-mounted transformers to the ground below. The brackets were made from acrylonitrile-butadiene-styrene (ABS) resin and had been in service for more than 30 years. Remnants of the fractured brackets were analyzed using optical and scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The exterior surfaces of all six brackets were alike and shared similar features, including witness marks, discoloration, mechanical deformation, and secondary cracking, along with crack networks. Both FTIR and TGA analyses indicated that the surface material was in a highly degraded state, likely due to weathering and thermal and ultraviolet exposure. This, in turn, led to the formation of cracks that propagated under the cyclic forces of vibration and wind. As the cracks grew larger, the weight of the transformer eventually overloaded the brackets, resulting in failure.
Melissa Kurtz, Failure Analysis of Transformer Brackets, Handbook of Case Histories in Failure Analysis, Vol 3, Edited By Larry Berardinis, ASM International, 2019, p 107–110, https://doi.org/10.31399/asm.fach.v03.c9001767
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New Handbook: Volume 11B
Now available in the Digital Library! Volume 11B serves as a reference and guide to help engineers determine the causes of failure in plastic components and make corrective adjustments through design and manufacturing modifications.