Software current limiting Hipot

Our test system complies with safety measures, as we have software tuned the system to prevent it from generating high current…..

And that’s not possible…

EN50191 states that for AC (alternating current), the current should not exceed 3 mA. For a DC (direct current), the current must not exceed 12 mA.

Now, many high-voltage systems have the ability to deliver a higher current.

We often see people software-limiting the tester to 3 or 12 mA, thus thinking they are creating a safe situation, this is not the case.

It should be taken into account that a high-voltage tester with an output current of 50 mA DC, for example, can never be adapted with a safety current limiter by setting the limit current to 12 mA.

However, the high voltage is switched off only a few milliseconds after the limit current is exceeded (delay/test interruption).

As one can see in the example below, after the software shutdown time, it is still possible for the current to reach a level greater than the limit defined in the standard.

So always make sure you have the right hardware preparations and create a safe testing environment.