How to view high voltage transient on Oscilloscope (Tektronix TDS1002B or TDS2014B)

[Raees]

Hi everyone. I m working of Variable input and variable frequency Flyback Switching Power Supply. since it is variable input form 130VDC to 850VDC, it has transient of high voltage on Mosfet (Drain). which can go 1000 VDC. I feel that it is dangerous for Oscilloscope to view high voltages.

I need help in this regard, that what should i do to view high voltage spikes on oscilloscope? any additional circuitry, or resistor divider network? or any other technique?

Following are the sample Waveforms at input 200VDC.

 

[schmitt trigger]

Tektronix sells several high voltage probes, all the way to 20 kV:

https://www.tek.com/high-voltage-probe-single-ended

 

[chuckey]

A compensated resistive divider sounds about right. Lets design it for you CRO 10:1 probe, 10 M +10 PF?. So ideally you want a 1.1 M, resistor to earth, then CRO point then 9 M to measurement point, the 9M would need a 1PF cap across. Thats 1 PF 1000VW,or you can get two pieces of insulated single core wire, solder one the the measuring end of the 9M, the other to the CRO point of the 9M. The free ends you then twist together, making sure the copper cores do not touch. View a voltage pulse shape with just the probe, make a note of it, then view it via your new 10:1 probe, if the rise time seems to have got longer, it means that your "1 PF" cap is too small and needs twisting up a bit more.
Frank

 

[Raees]

Hi schmitt trigger. Thanks for the reply. I have checked these probes. Their engineer have suggested P5100A. but i m searching for a cheap solution.

Hi Chuckey. thanks for reply. i am facing difficulty understanding most of the technical terms and sentences like "Lets design it for you CRO 10:1 probe, 10 M +10 PF?. So ideally you want a 1.1 M, resistor to earth, then CRO point then 9 M to measurement point, the 9M would need a 1PF cap across. Thats 1 PF 1000VW,or you can get two pieces of insulated single core wire, solder one the the measuring end of the 9M, the other to the CRO point of the 9M. The free ends you then twist together, making sure the copper cores do not touch. "
Can you make a schematic diagram of your design.