Hey guys! I'm stuck with my project(assignment) of building up a circuit by measuring voltage and current from an AC source with any equipment that is connected. I'm using the ACS714 Current sensor and based on it's typical application connection, I was able to draw out the circuit connection schematic for that portion.

I'm not very sure about the voltage sensing part.. I'm required to draw out the entire circuit schematic before doing the connection(hardware). Here are some similar projects I found but I'm having trouble understanding.. maybe a sample or guidance will help too! Thank you!

Reference:

http://www.instructables.com/id/Energino-an-Arduino-based-energy-consump...

http://www.instructables.com/id/ARDUINO-ENERGY-METER/?ALLSTEPS

## Re: HELP with sensing voltage and current(circuit schematic)!!

Both your links can only measure a dc voltage, so that does not help.

I suggest, if only because I am familiar with the material on the site, that you study our "Building Blocks" section. In there, you will find circuit diagrams, explanation and sketches for measuring and calculating the rms value of the voltage.

## Re: HELP with sensing voltage and current(circuit schematic)!!

Thanks for your reply!

What about measuring the phase between the voltage and the current?

## Re: HELP with sensing voltage and current(circuit schematic)!!

That is somewhat harder - possibly. Our general purpose library emonLib calculates rms current, rms voltage, true and apparent power; and from the last two, power factor. Unfortunately, by that method you are unable to determine whether it is leading or lagging, and it loses accuracy as it approaches zero, i.e. as the phase angle approaches 90°. To get that information, you would need to (say) delay the voltage signal in software by 90° and compute vars.

I have not looked in any detail into the properties of the ACS714, so I cannot say how, or even if, you could use that device for any of this. However, I would warn you that if you are using the public electricity supply, you must observe the proper safety precautions - especially creepage distances, between the mains and your low voltage circuits. Your supervisor should help you here.