Project Synopsis


Power Factor Measurement

Submitted by:

Binder Singh


Submitted to:

Prof. M.D Singh






Block diagram

Components required




Many individual have proudly influenced us during our undergraduate studies (B.Tech.) at Thapar university and it is pleasurevto acknowledge thiesr guidance and support.In TU, I learned many things, like, the project training is mainly aimed at enabling the student to apply their theoretical knowledge to practical as “The theory is to know how and practical to do how” and to appreciate the limitation of knowledge gained in the class room to practical situation and to appreciate the importance of discipline, punctuality, team work, sense of responsibility, money, value of time, dignity of labour.

I will like to express my gratitude towards Mr. MD SINGH who took keen interest in our project,Who helped me in every possible way and is source of inspiration for all the group members.

I would also like to thank HOD EE who motivated me to complete our  project with enthusiasm and hard work. He helped every time when I need

Binder singh


Power factor correction is the process of compensating for the lagging current by creating a leading current by connecting capacitors to the supply. A sufficient capacitance is connected so that the power factor is adjusted to be as close to unity as possible. Power factor explained.

Power factor correction aims to bring the apparent power value (measured in VARs or volt-amp-reactive) as close as possible to the amount of true power you are using in Watts. This will result in less current being needed to provide the same amount of true power.

Power factor can be calculated using an oscilloscope, by measuring the time difference between the voltage and current signal. These can be measured at any point in the wave as long as they are sampled in the same place. In this case it was logical to measure between zero crossing points (points in the wave where the voltage crossed the X-axis).

I designed the following circuit in Multisim. Assuming the current and voltage to the load are pure sinusoidal waveforms, the power factor can be measured. Each waveform is fed into a zero crossing detector (sometimes known as a sine to square wave converter) which is simply an 741 op-amp in comparator mode where the comparison voltage is 0V. When the sine wave is in the negative cycle a negative DC pulse is generated, and when the sine wave is positive a positive DC pulse is generated. The two square waves are then compared using an exclusive OR (XOR) logic gate, which will output a positive high DC pulse only when the square waves do not overlap, and 0V when they overlap. The output of the XOR gate is therefore time difference (delta t) between the two waves from the point they cross the zero point. This difference signal can then be timed by a microcontroller and converted to power factor using the following calculation (make sure your scientific calculator is in degrees not radians):

cos(phi) = f * dt * 360


cos(phi) – the power factor

f – The frequency of the measured supply

dt – delta t or time difference between the waves

360 – a constant used to give answer in degrees

In the pictures you will see three simulated oscilloscope traces for the circuit. The two input signals represent the current and the voltage to the load. I have given the second signal a phase difference of 18 Deg, to demostrate the theory. This gives a PF of approx 0.95.

In this project we will measure powe factor using controller, adc , CT and PT. Project is typical because we did not find proper circuit from internet. It will be long study then after we will implement on hardware. We will use DOT matrix LCD for this purpose. We will interfece lcd with controller IC. We can use any micrcontroller like avr , pic or Arduino.

Working of project-

We will use 12Mhz crystal to provide Clock to microcontroller.

There will IC 7805 as a voltage regulator. And two 1000µf and 470µf as a filtering capacitors.

We will use Arduino Microcontroller. We will use 16×2 LCD.

We will use Normal  ir sensor for counting purose


  1. Power factor controller
  2. Energy saving


We know that most of the high end industrial application devices have relays for their effective working. Relays are simple switches which are operated both electrically and mechanically. Relays consist of a n electromagnet and also a set of contacts. The switching mechanism is carried out with the help of the


Block Diagram:

Components required:

Arduino UNO R3

CT 25 A

PT 12v 2 A

Crustal 12Mhz

Cap 27pf

IC base 40 pin

7805 voltage regulator

diode in 4001

resistances 8.2k

cap 10 µf 15v

transformer 909v

copper clad board

ply board

micro switches.


Look around. Notice the smart “intelligent” systems? Be it the T.V, washing machines, video games, telephones, automobiles, aero planes, power systems, or any application having a LED or a LCD as a user interface, the control is likely to be in the hands of a micro controller!

Measure and control, that’s where the micro controller is at its best.

Micro controllers are here to stay. Going by the current trend, it is obvious that micro controllers will be playing bigger and bigger roles in the different activities of our lives.

These embedded chips are very small, but are designed to replace components  much bigger and bulky In size. They process information very intelligently and efficiently. They sense the environment around them. The signals they gather are tuned into digital data that streams through tributaries of circuit lines at the speed of light. Inside the microprocessor collates and calculators. The software has middling intelligence. Then in a split second, the processed streams are shoved out.

What is the primary difference between a microprocessor and a micro controller?

 Unlike the microprocessor, the micro controller can be considered to be a true “Computer on a chip”.

In addition to the various features like the ALU, PC, SP and registers found on a microprocessor, the micro controller also incorporates features like the ROM, RAM, Ports, timers, clock circuits, counters, reset functions etc.

While the microprocessor is more a general-purpose device, used for read, write and calculations on data, the micro controller, in addition to the above functions also controls the environment.



Low cost- it need less components . Major controller is arduino. Its not costly as compare to PLC.



Flexible  due to microcontroller

Easy to use- system is very easy to understand

Program –

int pin = 7;

float rads = 57.29577951; // 1 radian = approx 57 deg.

float degree = 360;

float frequency = 50;

float nano = 1 * pow (10,-6); // Multiplication factor to convert nano seconds into seconds

// Define floats to contain calculations

float pf;

float angle;

float pf_max = 0;

float angle_max = 0;

int ctr;

void setup()


 pinMode(pin, INPUT);



void loop()


for (ctr = 0; ctr <= 4; ctr++) // Perform 4 measurements then reset


  // 1st line calculates the phase angle in degrees from differentiated time pulse

  // Function COS uses radians not Degree’s hence conversion made by dividing angle / 57.2958

   angle = ((((pulseIn(pin, HIGH)) * nano)* degree)* frequency);

  // pf = cos(angle / rads);

   if (angle > angle_max) // Test if the angle is maximum angle


      angle_max = angle; // If maximum record in variable “angle_max”

      pf_max = cos(angle_max / rads); // Calc PF from “angle_max”



   if (angle_max > 360) // If the calculation is higher than 360 do following…


    angle_max = 0; // assign the 0 to “angle_max”

    pf_max = 1; // Assign the Unity PF to “pf_max”


   Serial.print(angle_max, 2); // Print the result


   Serial.println(pf_max, 2);


   angle = 0; // Reset variables for next test

   angle_max = 0;



  • Microcontroller
  • LCD display
  • Energy Meter
  • Visual display
  • Relay Circuit


– we are giving advanced idea which can be implemented on large level.

Hardware required-

Arduino programmer universal kit


Digital multimeter

Software required:

Keil software

ORCAD for PCB design

Proteus for simulation



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