HV Test in Isolators

Hi Everyone.

I am quite curious with digital isolators. I have read that these parts are being tested at a high voltage (kV) to ensure the durability and quality of devices over a life time. The HV testing includes Partial Discharge test and Leakage Test. If the supporting bodies such as UL, VDE and CSA are ignored/not be used as a point of "NOT POSSIBLE", is there a way that the breakdown of ions or forcing stresses in an isolators be possible? i.e. testing it in a lower voltage but longer period of time. Use a DC voltage? Or a way that it could be simulated in a laboratory without using a very large voltage?

Very important parameters in HV test:
1. Partial Discharge Test
2. Leakage Test

Here is an article i read regarding HV testing.
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I hope you could help me on this. I am currently researching for my thesis and i would really apreciate it if you could throw some ideas and/or suggestions. Thanks.