Differential High voltage measurement

[Amr Wael]

Hello ,
I am trying to measure differential high voltage signal , actually not very high it could reach 500V (+/-250) down to 10V. I designed a PCB with resistive dividers to attenuate the signal and then used voltage follower stage , difference opamps and error adjustment stage.\
After that I found out that I need over and under votlage protection circuits so the PCB became very expensive. Are there any other techniques for measuring high voltage differential signal for frequencies starting from DC to 300 KHz ?
Thank you very much in advance!

 

[danadakk]

Possiblity, eg. modify this design -

A 10X 100MHz Differential Probe

To make...or not to make...that is the question. I needed a probe that can dig out a 1V differential signal riding on a 60Hz 125VAC mains voltage. Many of the commercial probes aren't suitable for my purposes and are pricey. Therefore, the answer is...make.

hackaday.io

High Voltage Differential Probe Design and Build - Part 1

This project will be made of multiple parts. First, I'll explain the basics of designing a differential probe then the following posts wil...

electronicsplayground.blogspot.com

1GHz Active Differential Probe

Introduction ! Please note, documentation is still in progress ! This project was an ultra high input impedance (0.5pF||30MΩ or better) high bandwidth differential oscilloscope probe designed, buil…

xellers.wordpress.com

High-Voltage Differential Probe - Circuit Cellar

Amplifiers in Action A high-voltage differential probe is a critical piece of test equipment for looking at high-voltage signals. In his article, Andrew describes his design of a high-voltage differential probe with features similar to commercial devices, but at a considerably lower cost. It...

circuitcellar.com

Regards, Dana.

 

[KlausST]

Hi,

A voltage divider may be sufficient, since it divides down high voltage to safe voltage. It depends against what "high voltage" you want to protect.

For the circuit: an instrumentation amplifier is a good way.
Often the output of the Opamp goes to an ADC ... if so, there are ADC with differential input, simplifying input stage.

Klaus

 

[danadakk]

Page 6-16 of attached.


Regards, Dana.

 

[FvM]

High voltage, high bandwidth voltage dividers need capacitive compensation, ususally with individual adjustment, not particularly due to amplifier input capacitance but to account for the parasitic resistor parallel capacitance. Intended 300 kHz isn't really high bandwidth, you may come away without compensation at all, or at least with fixed compensation. The need for adjustment is specifically imposed if you want to achieve good high frequency CM attentuation.

PCB layout of the divider network plays however an important role.