Cutting the sacrificial coils into segments (cross sectioning)
is useful to see the overall coil taping workmanship
and VPI penetration and cure. It is important to note that
the coils may pass the electrical tests but still demonstrate
some flaws when sectioned. A full validation of the insulation
system serves to ensure that the system is designed to
meet its performance expectations. Sections cut from the
end arms of coils cannot be expected to look as well as
those cut from the slot section, where the shape of the turns
bundle and tape lay are well controlled by the straightness
of the section. The locations for sectioning, method of
examination, and acceptance criteria must be carefully
specified well ahead of time. Not all manufacturers will
have appropriate facilities available to perform this analysis.