Measuring with DC Load (plus remote sensing)

[sstepane]

Hi,

I would like to ask a question if someone experienced could clarify.
Assume two setups:
1 - DC Load, 10 cm long 10 sq. mm. thick wires with remote sensing attached
2 - DC Load, 100 cm long 5 sq. mm. thick wires with remote sensing attached
 I'm pretty sure that voltage will read properly, but what about current? Say 30 Amps with every setup?

Thanks in advance and sorry if it is a dumb question.

[jeroen79]

The voltage would always read "properly", what matters is where you want to read it.
If you want to rule out the voltage drop over the powerwires then you attach the load's sensewires to the source.
If you want to include the effect of the powerwires then you attach the load's sensewires to the load.

The current would flow through the load so unless you attach something in parallel the current measured by the load would be the same as the current going through the source.

See for yourself:
http://lushprojects.com/circuitjs

[sstepane]

Thanks, I just wanted to make sure that no measuring corrections required for current, unlike voltage.

[danadak]

Its fairly common to use a Rsense for current measuring to a load.
Usually done with a low value Rsense, 1 ohm or less. Conditioned by
an IA to reject CM voltages.

You can sense high side or low side with this technique, each coupled
with design decisions.

https://en.wikipedia.org/wiki/Current_sensing_techniques


http://cds.linear.com/docs/en/application-note/an105fa.pdf


https://www.microsemi.com/document-portal/doc_view/14646-an-7-a-simple-current-sense-technique-eliminating-a-sense-resistor


http://www.electronicdesign.com/test-measurement/choose-right-current-measurement-technique-your-application


http://www.vishay.com/docs/30304/currentmeasurement.pdf


Regards, Dana.