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Copper Arc Sphere

Copper Arc Sphere

This is a large copper arc sphere from a transformer oil sample. Its size indicates a very energetic arc.

Transmitted Off Crossed Circular Polarized Light and Reflected Darkfield Illumination


Copper arcing spheres are generated when an arc is discharged in the transformer under the cover of oil. It is the result of molten copper being formed by the arc and ejected into the oil by the rapid thermal expansion of the metal under the molten metal. The size of the arc particle is an indication of the strength of the arc.

Significance in the Environment:

There is some very energetic arcing going on in this transformer as indicated by this large arc sphere. Arc spheres vary in size but above 30 micrometers the molten metal tends to spash rather than exit as a single particle.

Characteristic Features:

Associated Particles: