Please don't use acronyms (or abbreviations) and assume everyone will know what you're talking about.
C+DF = capacitance and dissipation factor. IR = insulation resistance.
An understanding of what the testing is really telling you is important. The C+DF test method tells you about the condition of the exterior ground wall insulation as it appears from the interior conductor to the outside world (i.e. voids, holes, and mechanical "breakage" between insulation material layers). The IR test method tells you about the condition of the ground wall insulation's exterior surface (i.e. presence of moisture or contaminants). The two are NOT the same. And just so we're clear, neither tells you anything about the INTERNAL insulation that might be between multiple turns of the conductor.
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