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ADE7753 Calibrate with referrence meter

Question asked by SomeThing on Mar 13, 2013
Latest reply on Mar 18, 2013 by hmani

Hello

 

I doing student project about electric power meter. Hardware and micro controller board are work fine but I have accuracy problem.

 

This my hardware.

Use hall effect current sensor and divider network + c coupling  for current front end. (In datasheet hall effect have nonlinear error at 1.5%)

Use voltage transformer and divider network

 

This settting about ADE7753

PGA = 1 for both analog input (Current sensor and Voltage sensor)

Sampling rate at default. I not set.

 

This method to read electric variable.

1. I read Vrms and Irms synchronous with zero crossing interrupt and take average 100 times.

2. I read AEnergy and VAEnergy with timer interrupt and find diff of energy (this mean watt , right ? , dE/dT) Setting timer interrupt every 2.097152 Sec with timer 16 bit , but i assume don't care dT

 

And calibrate with external factor which store in micro controller. Use slope and offset correct (y = mx + c). I assume it 's should be linear because my load is incandescent lamp which pf = 1. This caribrate parameter with imin = 0.5A and ibase = 5A I found max percentage error about 5.4% in current section. and voltage error max at 0.2%

 

How to optimize it. For best accuracy. i hope it should less than about 2% for all range.

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