I post it again, here we are:
Here are some explanations about the need to do the leakage current testing at the rated voltage.
1) For electrolytics, there is a fundamental problem since all electrolytics have a leakage current, this is normal.
The problem is to know if this current is normal or not.
For this, it is first necessary to measure this current, what the "invention" proposed does not and then compare the result of this measurement with the technical specifications of the manufacturer.
These technical specifications for measuring the leakage current are made at rated voltage ...
http://www.rubycon.co.jp/en/catalog/e_pdfs/aluminum/e_twl.pdfIt is therefore necessary to test the electrolytic capacitors at rated voltage.
2) For other types of capacitors, it is essential to check if the breakdown voltage has not decreased.
A capacitor may have a low leakage current at low voltage while having a greatly reduced breakdown voltage.
This is due to a physical characteristic of the insulators: the dielectric strength.
see here to understand what it is:
https://en.wikipedia.org/wiki/Dielectric_strengthYou will find that the dielectric strength of polystyrene, for example, is 19.7 and that of air is only 3.
What happens when a capacitor has been punctured by a surge?
The insulation is pierced and some of the insulation has been replaced by air or gas from the spraying of the insulation.
As a result, at this point, the polystyrene is replaced by air and the dielectric strength is then only 3 instead of 19.7.
The breakdown voltage is then reduced by 6.56 times and this is not noticed during the leakage current test at low voltage because the leakage current of air and polystirene are substantially the same.
Thus, testing a condensator at low voltage is dangerous because it let you think your capacitor is good when it is'nt.
When you power on such a capacitor at rated voltage without current limitation, it will blow up and may injure you.