Metal Residue From a Transformer Oil Sample
This is a steel fragment generated by grinding that was heated sufficiently to oxidize on the
surface. The colors on the particle are the thin film interference colors created by the surface metal oxides. This
indicates that the particle was created in the atmosphere and not in the oil filled transformer.
Transmitted Circular Polarized Light and Refected Darkfield Illumination
Metal fragments are often seen in oil samples. In this case the surface oxide films indicate creation in the atmosphere
and not in an oil filled environment.
Significance in the Environment:
Metal particles such as these are typically a manufacturing residue. They may be introduced during rework or from nearby work if the
transformer is air-breathing.