How to measure high currents ..

[GoranP]

Hello.

I came across a new problem, a new application. I/we have to measure a high DC current, upp to 100A, (maybe higher later up to 300A)

What is the best solution to make this with your bricklets? 
Like some form of shunt between +in and +out on the Voltage/Current Bricklet ?
If I read your schematic correct, you use a resistans with 4milliOhm in the bricklet. So how could/should i calculate to enhance the measuring range ?
Thanks for tips ...

[batti]

Hello Goran,

the Voltage/Current Bricklet measures current by measuring the voltage drop on a resistor (called shunt). That is the 4 milli Ohm resistor you have found.

With U=R*I and P=U*I you can do the math. The resistor is selected for the specified measurment range of the Bricklet. 100A or more are not possible with it. Unfortunately we don't have an easy solution for that at the moment. A trick is to use a "100A shunt" (you find it on ebay) witch has typically 0,75 milli Ohm. To use it you have to remove the 4 milli Ohm resistor on the Bricklet and connect the shunt via wires to it. After that you have to correct the measured current of the Bricklet (val/4*0,75).

[GoranP]

Thanks for Your answer. 

For me is it oft so, when I'm coming across a problem and dont know how solve it, the best thing for me then is to explain the problem for some one else. Then comes oft ideas like "so can I solve it".
So was it also yesterday, after writing I had an almost equal idea, to use an external shunt resistor. But I think I will keep the origin resistor onboard. For that means, with example of a "100A shunt", that be that I measure 120A instead. 
 Another thing I also found, most "commersal" shunt are designed for 60mV drop, the IC circuit seems to use 80mV as full scale.

I don't if this project will be realised or not, but it's always interesting to look at solutions...
Anyhow, thanks for the tip..