Acquire a AC signal and read Breakdown Voltage

[Danny0806]

Hi Guys

I hope you are doing well and safe.

As part of my project, I need to monitor an AC Voltage waveform and record the RMS value when the breakdown happens. I roughly know how to acquire data from videos I have watched, however, it is difficult for me to produce a solution that reads the Breakdown Voltage Value. Ideally, I would also take a screenshot along with the breakdown voltage value,

In case you are not familiarised with this topic. When a breakdown happens the voltage will drop immediately to zero, So what I need is to measure the voltage just before it falls to zero, and if possible take a screenshot. I am attaching an image of a normal waveform (black) with a breakdown one (red).

[santo_13]

I would approach this as - breakdown voltage is the maximum voltage measured across the DUT at a given stimulus, now convert this peak voltage into rms.

Any reason why just finding the maximum value of the red waveform would not give you the breakdown voltage?

[RTSLVU]

Actually that is a DC voltage and I am not sure what knowing the RMS of the waveform ringing is going to tell you.

But as santo said measure the peak of the red waveform. That's your breakdown voltage

[Danny0806]

Hi Santo,

Thanks a lot for your reply.

Yes, I am actually measuring the peak of the red voltage waveform. However, I am struggling to find a way to make the program read the peak just before it goes to zero. That is the part I am not sure about.

[Henrik_Volkers]

How I would approach this:

1:) detect the zero slope

  if you know the actual slope sign : go for a threshold near zero.

 if you have AC (sine? 😞 apply a highpass filter (differentiation) , the slope will create a nice peak , use a window comparator for detection. cut the data +-1µs of original data around the the peak,

2.) depending on the peak sign (of the HP-signal) use peak (or valley) detektion on the raw signal.

If you append some measurement data (breakdwns in both polarities)  in a vi, stored as a constant or in a graph (make current values default)  file like .wfrm  or .tdms  or something one can easely read in LabVIEW.. it looks like a coffebreak task to make a vi 😉

[santo_13]

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@Danny0806 wrote:

Hi Santo,

Thanks a lot for your reply.

Yes, I am actually measuring the peak of the red voltage waveform. However, I am struggling to find a way to make the program read the peak just before it goes to zero. That is the part I am not sure about.

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One better way is to treat the signal as an AC signal, find the mean (which gives you the virtual zero-crossing), and now find the nearest peak to the zero after the last zero crossing.