Is atmega328 able to measure AC voltage?

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi all,
I was trying out a programn to measure ac voltage done by Home | OpenEnergyMonitor on the computer but seemed to have some issue to get the negative half of the sinewave as seen below. Could anyone pls guide me on it.Is the Atmega328 unable to detect ac voltage?

2

You could use an op-amp with a level conversion to shift the 0 point to 2.5V.

3

It also depends on what you want to measure on your AC signal:-

  1. Wave shape
  2. Peak to peak voltage
  3. Peak voltage
  4. RMS voltage
  5. Average voltage

All require silightly different techniques and setups

4

Thanks everyone! Since the ADC can't read the AC sine wave, the only way I could do with it is to get a full bridge rectifier to rectify the signal into DC. However there is a problem with it because I need to know the negative cycle zero crossing point of the waveform.Is there any way to detect it?

5

However there is a problem with it because I need to know the negative cycle zero crossing point of the waveform.

This is where you stop being theoretical, and start telling us exactly what you are trying to do.

6

Did you go to the root of that website and look up how to build the voltage and current probe?

http://openenergymonitor.org/

Maybe scroll down and click on "Input modules"?

And you might read that there is an App note with gasp math. Which should trigger an episode and we can enjoy HAM in peace.

7

My apologies if I didn't give a detail introduction of what I am working on, I am currently working on building an auto synchronization of ac power which requires the same frequency, magnitude(rms) and phases of the 2 voltages(mainsource and synchronous motor source). Therefore I need something to monitor the mentioned parameters. Therefore I am seeking opinion as to the best possible ways via arduino in monitoring the frequency and the zero crossing point for comparision so as to check if the 2 voltages are in phase.

8

Look at your inverted output diagram. The voltage drops to 0 at many points. Is it not enough to measure when the voltage is 0?

Your project may actually be very difficult to perform with an Arduino, given the slow response of the ADC.

Measuring two power sources simultaneously is not possible.

Even if you were to figure out how far out-of-phase they are, how do you propose to correct the out-of-phase-ness?