Power factor measurement using Atmel AVR Micro-Controllers

To learn about the power factor measurement, you should have a basic knowledge of power factor. There are three types of loads.

  1. Resistive
  2.  Inductive
  3. Capacitive

Power factor measurement using Atmel AVR Micro-Controllers
When we apply AC voltage to resistive loads it will not change the current wave form. But inductive loads will force to lag the current waveform and in the case of capacitive loading it will force to lead the current waveform than voltage waveform.
You can see the waveforms of inductive load. The phase shift of 30 degree is present in the current waveform.
The power factor is basically the “angle cosine of that lagging current”. In simple words, current is lagging by voltage with some angle and if we take the cosine of that angle we will get power factor.

Zero Cross Detection:

Zero cross detection is a method which can enable us to measure the time between voltage and current. In this technique we get a high value (i.e. 1) whenever a zero will cross the system. There are many ways to implement it. But remember, this technique is the heart of this project so implementation must be accurate. In this project we implemented zero crossing using LM358 an 8 pin IC having dual amplifiers in it. In zero crossing, we have to get a “high” value during crossing of zero in waveforms. So to get  that  value  we  use  amplifier  as  a  comparator  which  will  compare  the  non  inverting reference value and then act accordingly.
We will use a 16×2 LCD to show our results and ATmega 8 or ATmega16 can be used for the project. In the simulation, take upper sine generator as output of Potential Transformer (PT) and lower sine generator as output of Current Transformer (CT). The reason behind using CT and PT is, we cannot give high voltage to the IC LM358. It will burn the IC badly. So first step down the voltage and step down the current at such extent that the highest peak of current and voltage is not more than 5V. If you have no idea of using CT and PT in the real systems then see the links below.
Power factor measurement using Atmel AVR Micro-Controllers Schematic
 
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About The Author

Ibrar Ayyub

I am an experienced technical writer with a Master's degree in computer science from BZU Multan University. I have written for various industries, mainly home automation and engineering. My writing style is clear and simple, and I am skilled in using infographics and diagrams. I am a great researcher and am able to present information in a well-organized and logical manner.

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