Greeting folks,

I am interested in ESD Test (according to IEC 61000-4-2), and I have a question about it.
When we perform an ESD with ESD Gun to an equipment, we see roughly a current waveform from oscilloscope as in below;

So, my question is why we are seeing waveform like this? I mean in initially current value is increasing and decreasing, but after that it is rising again. What is the rationale of second increment?
My second question is why maximum value of current is 3.75 Amp. per kV? As you know, in test setup, esd gun tip and ground strap are short circuited. So, does not it have to be higher than 3.75 Amp?


ESD Test Current Measurement Setup (For Calibration)

Thoughts? Opinions?
All serious answers are very much appreciated.

Kind regards.

 

I would say the second peak is due to oscillation with the inductance of the wires, which is damped a lot. The peak current is probably due to series resistance inside the esd gun.

 

Not sure if this applies but sometimes overload recovery of vertical
amp in scope can compromise observed measurements.

See attached on topic.

Regards, Dana.