Hig voltage current sensing using ACS723 (low current breakout)

Other Miscellaneous
1

Hi there,

I have a research project where I am in need of measuring the pulsed DC current that is produced during stimulation of this neuromuscular stimulator:

DS7AH - https://digitimer.com/products/human-ne … l-product/

The stimulation pulse will be in the order of 0-1000mA (0-1A) and could be a maximum voltage between 0 and 400V. The pulse width is only 200uSec.

The experimental setup would be that this stimulator is connected to electrodes over a participant’s muscle/nerve on the skin surface.

I feel pretty confident that the ACS723 (low current) module ( https://www.sparkfun.com/products/14544) should work in sensing the pulsed current IF I position the IP- and IP+ terminals on the “low-side” of the current path (i.e., after current has passed through the muscle/nerve/skin). Although, I have read that “low-side” current sensing has its own issues…

I know this ACS723 chip has a pretty strong isolation voltage; however, the product webpage explicitly states that the PCB is not rated for high voltages. I am wondering whether I could safely use this board on the “high-side” of the current path, given that a max of 400V would only be presented for, at most, 200uSec? If not, is there any alternative available?

Kindest regards!

2

Hello tredude, and thanks for your post.

We don’t recommend using high voltages with this board, but you would probably be OK.

Chances are slim that anything would happen, but there is the risk that you could damage whatever controller you have connected to the low voltage side of the board and you could potentially cause a shock to anyone operating the controller. It’s ultimately up to you to decide if it’s worth the risk to proceed.

3

Thank you for your reply!

Do you think it would be safer if I used some sort of linear optocoupler on the low-voltage side of the board? To help further isolate distal electronics from potentially high voltages?

The most likely electronics that the Vout would be connected to would be a BNC input on a DAQ system like this:

https://www.adinstruments.com/products/powerlab

Alternatively, is there any other options for current sensing in this sort of situation? Would any of those noninvasive hall effect/magnetic thingos do a decent job?

4

You could give an optoisolator a try, but I don’t know how well that would work.

A clamp on DC current probe might work as well, but I’ve never used one so I don’t know for sure how quickly they react. You’d just need to give it a try and see.