Charred Paper Fiber From Transformer Oil
This charred paper particle is from an oil sample collected
from a 8400kVA transformer. This
transformer was reportedly gas blanketed and sealed. This particle shows the
contours of the paper fibers and the edge
fracture pattern typical of charred paper. These patterns are often absent in
charred paper, in which case the origin of
the char can not be determined directly. When these patterns are present the origin
of the char can be determined. These
particles indicate heating of the paper insulation in excess of 250 degrees Celsius.
Transmitted Oblique Off Crossed Circular Polarized Light and Darfield Reflected light
Illumination
Definition/Function:
Charred paper fiber is paper fiber that has been heated to a high enough temperature for
a long enough time to loose much of
its hydrogen and hydroxyl groups and to increase the carbon coordination in its
structure. I this process the fiber becomes
increasingly opaque, it shrinks, and the reflectivity of the surface of the fiber
increases. The structure of the fiber is
often maintained during this process.
Significance in the Environment:
Charred paper fiber in transformer oil often indicates a significant hotspot in the core
at some location.
Characteristic Features:
Associated Particles:
Charred paper fiber is generally associated with much greater numbers of severely
degraded paper fiber. The severely
degraded paper fiber is created at an earlier stage in the formation of a hotspot.
References:
