AnsweredAssumed Answered

Calculate Steady RMS value with AD7607 and Blackfin 504F

Question asked by sijeo.philip@aydintech.com on Jun 17, 2013
Latest reply on Jul 5, 2013 by SachinV

Hi,

In my application i am trying to measure three phase current and voltage along with Neutral thus we are using 8 channel simultaneous sampling ADC... Currently i am collecting 128 samples over 2 periods of the input i.e. 40msec and then passing it through a bandpass filter and then doing a radix 4 fft , then i am calculating the mean of the output of  FFT  along with multiplication factor and displaying the result... I am not sure if this is the best way to achieve a stable reading of 2 cycle of input as more than 2 cycle cannot be afforded for measurement in my application

 

JFYI

... I am not using a zero crossing detection i am just sampling at a fixed period of 40 msec using ACM and DMA for data collection and making sure of the sampling time.

Can anyone guide a better method as i am still seeing fluctuations of around 30mV .. as my experience in metering is zero...

 

In Anticipation

 

Thanks

Sijeo Philip

Outcomes