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Measurement Techniques
Understanding Measurement Currents
Insulation resistance is defined as the dc test voltage divided by
the total current flowing in an insulator. The total current has four
components; capacitive current, absorption current, conductance
current and leakage current. If a generator has wet or
contaminated windings conductance current will be present.
In the case of dry insulation conductance current may be negligible,
and the leakage current may be low, in which case the absorption
current will dominate the total current measured.