Typical (apparent) insulation resistance vs. time curve from which the points are extracted to calculate Polarisation Index PI = 3.53 (from T2 = 600 s and T1 = 60 s); the points T1 and T0 could be used for DAR, and T3 could be use for a different ratio of PI.
The data was measured with Megger S1-568 instrument (insulation resistance tester) at 500 V on a 55 kW motor, rated 400 V.
polarisation_index_definition_magnetica.png
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