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How to obtain accurate power factor reading?

Question asked by TrendChaser89 on Mar 12, 2013
Latest reply on Jul 30, 2013 by TrendChaser89

Hello All,

 

     I am developing an energy meter using the ADE7753 metering chip.  Apart from the energy reading, I also wanted to display the power factor.  The ADE7753 does not have a register for the power factor so I thought of dividing the active energy reading with the apparent energy reading to get the equivalent power factor.  In our school laboratory, we do not have a reference meter and an accurate source such as phantom loads that can be used for calibration.  What we have is a power analyzer called NANOVIP Plus which is capable of reading voltage, current, power, energy and power factor values. So I put up a lamp bank consisting of five 100 W light bulbs in parallel and measured the current using NANOVIP.  In my design, I used the current reading from NANOVIP which is 2.18 A as the base current and 10 A for the maximum current. With these values and the five 100 W light bulbs as load, I performed the calibration routines for active and apparent gain.  I also performed the calibration routine for watt offset using a 10 W light bulb.  I was unable to do phase calibration because I do not know how to alter the power factor of the load that I was using such that it will be 0.5 lagging and the current is maintained at 2.18 A, the base current.  I am using a current transformer for current sensing.  May I ask for suggestions on how to go about the calibration for low power factor loads?

 

     Thanks a lot.

 

Best Regards,

 

TrendChaser89

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