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Insulation Resistance -old requirement

Ismael Ochoa
I have just come across a insulation resistance (IR) test requirement stating that the IR  R2/R1 > 0.7 where R1 is the IR before a Dielectric test ( 2000VAc for 1 min ) and R2 is the IR after the Dielectric test. Has anybody seen this requirement before?, if so what are the technical basis for this? Nowadays, standard only requests that IR should greater than certain value which depends on the equipment rated voltage.
Comments will be appreciated

I
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    Do you have more information about the type of equipment this test was for ? With modern solid plastic insulations the results are so near open circuit that the results are dominated by contamination or surface tracking. I am aware that certain types of capacitor insulation, such as oily paper, actually change during a hi pot test, as the application of the test voltages tends to pull the conductors together and oil gets squeezed a bit,  but then this  ' self heals' later. I have seen specs with different hot and cold limits, and if the hi pot test was DC, I;d be wondering about dielectric recovery, but this is not it.
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    Do you have more information about the type of equipment this test was for ? With modern solid plastic insulations the results are so near open circuit that the results are dominated by contamination or surface tracking. I am aware that certain types of capacitor insulation, such as oily paper, actually change during a hi pot test, as the application of the test voltages tends to pull the conductors together and oil gets squeezed a bit,  but then this  ' self heals' later. I have seen specs with different hot and cold limits, and if the hi pot test was DC, I;d be wondering about dielectric recovery, but this is not it.
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