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Black on Paper, Transformer Fretting Wear Through the Microscope

Discolored Paper from a Transformer

This is a tapelift from a section of black discoloration on paper insulation from a transformer. The paper fibers show mechanical degradation and the black particles show metallic depolarization at the edges. The particles must be metal or graphite. Soot will not depolarize a polarized beam of light.

Transmitted Circular Polarized light


Significance in the Environment:

Characteristic Features:

Associated Particles: