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AUTOMATIC POWER FACTOR CORRECTOR USING
MICROCONTROLLER
ELECTRICAL ENGINEERING DEPARTMENT Page 1
A
PROJECT REPORT
ON
AUTOMATIC POWER FACTOR CORRECTOR
USING MICROCONTROLLER
PREPARED BY: GUIDEDBY
1) Parmar Kevin S. 126370309079 Mr. M. G. Vasava
2) Mehta Vijal B. 126370309082 Ms. V. B. Patel
3) Pancholi Raj K. 126370309086 Mrs. R. P. Ghariya
4) Mirza Ashif A. 126370309089
5) Yadav Amit D. 126370309101
*************************************************************************
N. G. PATEL POLYTECHNIC
At.: Isroli, Po. Afwa, Ta. Bardoli, Dist.: Surat- 394620.
Tel.: (02622) 291106 , Mo.: 9228000868, Fax. : (02622) 290488.

MICROCONTROLLER
Electrical Engineering Department
CERTIFICATE
This is to certify that Parmar Kevin S.,Mehta Vijal B., Pancholi Raj K., Mirza Ashif,
Yadav Amit D.; Pen 126370309079, 126370309082, 126370309086, 126370309089,
126370309101 of Diploma in Electrical Engineering have successfully completed the
Term-work of “AUTOMATIC POWER FACTOR CORRECTOR USING
MICROCONTROLLER” offered during the academic year October-November 2014.
GUIDED BY: HOD:
Mr. M. G. VASAVA Mr. V. K. PATEL
Ms. V. B. PATEL
Mrs. R. P. GHARIYA
PRINCIPAL
(PROF. A. B. SUTHAR)

MICROCONTROLLER
ACKNOWLEDGEMENT
It is a known fact that words are never sufficient to express the exact
amount of gratitude that a person feels but words are the only way we can
express our feelings. We would therefore like to express our thanks to our
project guide, Mr. M.G.VASAVA for the invaluable guidance, encouragement
& kind co-operation extended by him during the term of our project. We would
also like to express our gratitude to Ms. M.M.PATEL& Mrs. R.P.GHARIYA
for her kind help & guidance towards making our project to this success.
STUDENTS NAME :- ENROLLMENT NO. :- SIGN :-
1) Parmar Kevin S. 126370309079
2) Mehta Vijal B. 126370309082
3) Pancholi Raj K 126370309086
4) Mirza Ashif A. 126370309089
5) Yadav Amit D. 126370309101

MICROCONTROLLER
ABSTRACT
The thirst for new sources of energy is unquenchable, but we
seldom realize that we are wasting a part of the electrical energy every day due
to the lagging power factor in the inductive loads we use. Hence there is an
urgent need to avoid this wastage of energy.
Before getting into the details of Power factor correction, let’s
just brush our knowledge about the term “power factor”. In simple words power
factor basically states how far the energy provided has been utilized. The
maximum value of power factor is unity. So closer the value of P.F to unity,
better is the utility of energy or lesser is the wastage. In electrical terms Power
factor is basically defined as the ratio of the active power to reactive power or it
is the phase difference between voltage and current. Active power performs
useful work while Reactive power does no useful work but is used for
developing the magnetic field required by the device.
Most of the devices we use have power factor less than unity.
Hence there is a requirement to bring this power factor close to unity. Here we
are presenting a prototype for automatic power factor correction using PIC
Microcontroller.

MICROCONTROLLER
INDEX
 Acknowledgement
 Abstract
 List Of Figures
 List Of Tables
 Chapter:-1 Introduction...........................................................01
 Chapter:-2 Block Diagram with Explanation..........................03
 2.1Block Diagram..................................................04
 2.2Explanation of Block Diagram……………..…..05
 Chapter:-3 Circuit Diagram With Description.......................... 06
 3.1 Circuit Diagram………..…………………………07
 3.2 Explanation of Circuit Diagram.......................08
 Chapter:-4 Components List With Description…………......…11
 4.1 LIST Components………….……....………..12
 4.2 Components Description……………..….13
 4.2.1 PIC16F877A Microcontroller………..13
 4.2.2 IC7805……..………………….14
 4.2.3 Crystal oscillator
 4.2.4 Capacitor…………………………….…..16
 4.2.5 Resistor………………………
 4.2.6 Diode..............8
 4.2.7 Relay…………………………………….19
 4.2.8 Current transformer…..……..…………………..20

MICROCONTROLLER
 4.2.9 Potential transformer......................21
 4.2.10 LCD…………………………………22
 4.2.11 Transistor……………………………...
 Chapter:-5 Costof project…………………………………………………..
 Chapter:-6 Advantages, Disadvantages & Application ............................27
 6.1Advantages……………….………………………………....…28
 6.2Disadvantages……….…………..……………..............…..…28
 6.3Application……………….……………………………………28
 Chapter:-7 References……………………………………..……………….29

MICROCONTROLLER
ABSTRACT
The thirst for new sources of energy is unquenchable, but we
seldom realize that we are wasting a part of the electrical energy every day due
to the lagging power factor in the inductive loads we use. Hence there is an
urgent need to avoid this wastage of energy.
Before getting into the details of Power factor correction, let’s
just brush our knowledge about the term “power factor”. In simple words power
factor basically states how far the energy provided has been utilized. The
maximum value of power factor is unity. So closer the value of P.F to unity,
better is the utility of energy or lesser is the wastage. In electrical terms Power
factor is basically defined as the ratio of the active power to reactive power or it
is the phase difference between voltage and current. Active power performs
useful work while Reactive power does no useful work but is used for
developing the magnetic field required by the device.
Most of the devices we use have power factor less than unity.
Hence there is a requirement to bring this power factor close to unity. Here we
are presenting a prototype for automatic power factor correction using PIC
Microcontroller.

MICROCONTROLLER
LIST OF FIGURES
SR.
NO.
CONTENT
FIGURE
NO.
PAGE
NO.
1 Block diagram of power factor corrector 2.1 04
2 Circuit diagram of power factor corrector 3.1 07
3 PIC16F877A Microcontroller 4.2.1 13
4 IC 7805 Positive voltage regulator 4.2.2 14
5 Crystal oscillator 4.2.3 15
6 Electrolytic capacitor 4.2.4 16
7 Ceramic capacitor 4.2.5 17
8 Resistor 4.2.6 18
9 Diode 4.2.7 19
10 Current transformer 4.2.8 20
11 Potential transformer 4.2.9 21
12 Transistor 4.2.10 22

MICROCONTROLLER
LIST OF TABLES
SR.
NO.
CONTENT TABLE
NO:
PAGE NO.
1 4.2.1 14
2 4.2.3 16

MICROCONTROLLER
CHAPTAR 01:
INTRODUCTION

MICROCONTROLLER
INTRODUCTION:
This project discusses the need for power factor correction and provides a
suitable DIY that could be used for small-scale industries and establishments.
When voltage and current are in same phase with each other with an A.C
circuits, electrical energy drawn from the source gets fully converted into
another form of energy and the power factor is said to be unity.
As the power factor drops, the system becomes less efficient. A drop
from unity to 0.9 in the power factor results in 15 per cent more currents
requirement for the same load. A power factor of 0.7 requires approximately 43
per cent more current.
In industrial units and establishments, most of the loads are electrical
motors and air-conditioning units. These loads are inductive in nature, where
the current lags the applied voltage and the power factor is termed as lagging
power factor. With capacitive loads, the current leads the voltage and the power
factor. The objective therefore should be to neutralise loads by connecting
capacitors across the load, which have leading power factor.
By improving the power factor you can save money on your electricity
bill and also derive the following benefits;
1. Reduction of heating losses in transformers and distribution
equipment.
2. Longer equipment life.
3. Increase in the capacity of your existing system and equipments.
While power factor correction is required for efficient use of electrical
power over correction of power factor correction is not recommended. In
this project over correction is not considered; we have considered power
factor between 60 per cent and 90 per cent only due to inductive loads.

MICROCONTROLLER
CHAPTAR 02:
BLOCK DIAGRAM WITH DISCRIPTION

MICROCONTROLLER
BLOCK DIAGRAM:
Fig.2.1 block diagram
POWER SUPPLY
CAPACITOR
BANK
LCD DISPLAY
PIC16F877A
MICROCONTROLLER
RELAY
STEP DOWN
TRANSFORMER
BRIDGE
RECTIFIER
AND FILTER
5V – 12V
REGULATED
POWER
SUPPLY
VOLTAGE AND
CURRENT STEP
DOWN
ARRANGEMENT

MICROCONTROLLER
BLOCK DIAGRAM DISCRIPTION:
 VOLTAGE AND CURRENT STEP DOWN ARRANGEMENT: In this
section we are using current transformer and potential transformer for the
step down of voltage and current at a specific value.
 BRIDGE RECTIFER & FILTER: Bridge rectifier and capacitor will
convert 12 volt A.C. into Pure D.C. voltage because all electronic
components will work only on D.C supply.
 PIC MICROCONTROLLER: A PIC microcontroller s a small computer
on a single integrated circuit containing a processor core, memory, and
programmable input/output peripherals. Here it calculate power factor and
give signal to operate a relay as per program instruction
 REGULATED POWER SUPPLY: Relays will operate only on 12 volt but
other components like LCD, CPU, ADC, will work on regulated 5 volt. so
we have to convert 12V DC to regulated 5V DC Supply.
 RELAY: A relay is a switch worked by electromagnet .it is useful if we
want a small current in one circuit to control another circuit containing a
device such as lamp or electric motor which requires a large current or if we
wish several differential switch contacts to be operated simultaneously.
 CAPACITOR BANK: It used to improve power factor by connect it in
parallel with line. it supply a reactive power in a line for compensating a
active power to improve power factor

MICROCONTROLLER
CHAPTER 3:
CIRCUIT DIAGRAM WITH DISCRIPTION

MICROCONTROLLER
CIRCUIT DIAGRAM :
Fig.3.1 circuit diagram

MICROCONTROLLER
CIRCUIT DIAGRAM DESCRIPTION:
Fig..3.1 shoes the circuit of a microcontroller based power factor
corrector. The circuit is built around PIC16F877A micro-controller, 230V
A.C primary to 9V, 300mA secondary transformer, current transformer, 3
relays, a 16*2 LCD display and few other components.
Microcontroller PIC16F877A:
Microcontroller PIC16F877A is the
heart of the circuit. It is used to detect the phase difference between
voltage and current in the A.C mains supply line. It also connects
capacitor across the inductive load through a relay as explained below.
IC1 is low power high performance. COMS 8 bit microcontroller. Its
main features are 8 Kb flash memory, 256 byte EEPROM, 368 byte ram,
33 i/o pins, 10 bit 8 channel analogue to digital converter, three timers, a
watchdog timer with its own chip oscillator for reliable operation and
synchronous IC interface.
IC1’s port pins RBO through RB7 are connected to do through D7 of
LCD 1 port pins RD5,RD6 & RD7 of IC1 are connected to control pins
resistor select of LCD 1, respectively port pins RC4 through RC6 are use
to control relays RL1 through RL3 respectively.
In this project, three different PFC capacitors are used to connect across
the inductive load through RL1, RL2 & RL3 relays. If power factor is
between 60 per cent and 70 per cent RL1 is energized. RL2 is energized if
power factor is over 70 per cent but within 80 per cent and RL3 for power
factor above 80 per cent but within 90 per cent.
When port PIN RC4 of IC1 goes high, transistor T3 conducts and relay
RL1 gets energized. This makes a PFC capacitor to connect across the
inductive load to neutralise the lagging power factor similarly, PORT PIN
RC5 and RC6 can control relays RL2 and RL3 to neutralise the lagging
power factor.
A 4 MHz crystal oscillator is connected two pins 13 & 14 of IC12 provide
the basic clock frequency power on reset is provided by the combination
of resistor R1 and capacitor C1. Switch S1 is use for manual reset of the
micro controller. Port PINS RA0 & RA1 of IC1 receive the zero crossing
detection pulses of voltage and current respectively.
Zero crossing detection. The zero crossing is the instantaneous point in
an A.C waveform at which three is no voltage present. In these circuit,
two zero crossing detectors are employed to get the phase angle of voltage

MICROCONTROLLER
and current. First zero crossing detector is used for detecting the point
where the voltage crosses zero in either direction sinusoidal A.C signals.
The mains voltage 230V A.C. is stepped down by transformer X1 to
deliver a secondary output of 9V. The transformer output is rectified by
full wave bridge rectifier BR1 & applied to the base of transistor T1
through resistor R6. Capacitor C4 charges to its maximum value through
diode D4 and provides supply to collector of transistor T1. Zener diode
ZD1 regulates the voltage to 5.1V which is suitable for microcontroller
input.
When rectified output transits through zero, T1 becomes off and its
corrector goes high. The detected voltage pulse is applied to port pin RA0
of IC1.
Similarly, zero crossing detection for current is done through current
transformer X2, bridge rectifier BR2, transistor T2 and zener diode ZD2.
The current sample rectifier by bridge rectifier BR2. When rectifier output
goes through zero, a pulse is generated an applied to port PIN RA1 of
IC1.
The time difference between the voltage and the current pulses is
calculated by the program embedded in the micro-controller. The power
factor value is then calculated and displayed on the LCD. By knowing the
value of power factor, we can calculate the value of PFC capacitor
required.
PFC capacitor value. For neutralising the inductive reactance, we need
to determine the value of PFC capacitor including its kilo-volt-ampere-
reactive rating, which need to be connected across the load. There are
various methods to determine the corrective reactive power rating. Here
we present a very simple method to know the KVAR in two steps:
1. Measure the RMS line voltage and RMS line current. Power factor is
already displaying on the LCD. For a single phase system.
kW =volts*amps*PF /1000
2. Now determine the corrective reactive power needed for obtaining the
desired PF by multiplying the kW value, as found above, with the
selected value of PF multiplier from table. For example,if the total
plant load is 100kW at 60 per cent power factor. Capacitor KVAR
rating necessary to improve power factor to 90 per cent is found by
multiplying kW by the 0.849 multiplier in the table which gives 84.9
KVAR or roughly 85 KVAR. The standard PF capacitor rating nearest
to 85 KVAR should be used.

MICROCONTROLLER
CHAPTER: 04
LIST OF COMPONENTS WITH
COMPONENTS DETAILS
LIST OF COMPONANTS:

MICROCONTROLLER
SR.NO COMPONANTS NAME
1
PIC16F877A MICROCONTROLLER
2
CAPACITOR
3
RESISTOR
4
CRYSTAL
5
DIODE
6
RELAY
7
IC 7805 VOLTGE REGULATER
8
TRANSISTOR
9
CURRENT
10
POTENTIAL TRANSFORMAR
11
LCD DISPLAY
12
40 PIN IC SOCKET
Table no.4.1 List of components

MICROCONTROLLER
COMPONENT DESCRIPTION:
4.1 MICROCONTROLLER:
A microcontroller is a small computer on a single integrated circuit
containing a processor core, memory, and programmable input/output
peripherals. Here we will use the PIC16F877A.
PIC16F877A:

Fig.4.1 pic16f877A
PIC 16F877 is one of the most advanced microcontroller from Microchip. This
controller is widely used for experimental and modern applications because of
its low price, wide range of applications, high quality, and ease of availability. It
is ideal for applications such as machine control applications, measurement
devices, study purpose, and so on. The PIC 16F877 features all the components
which modern microcontrollers normally have.
General Features
o High performance RISC CPU.
o ONLY 35 simple word instructions.
o All single cycle instructions except for program branches which are two
cycles.
o Operating speed: clock input (200MHz), instruction cycle (200nS).
o Up to 368×8bit of RAM (data memory), 256×8 of EEPROM (data memory),
8k×14 of flash memory.

MICROCONTROLLER
o Pin out compatible to PIC 16C74B, PIC 16C76, PIC 16C77.
o Eight level deep hardware stack.
o Interrupt capability (up to 14 sources).
o Different types of addressing modes (direct, Indirect, relative addressing
modes).
o Power on Reset (POR).
o Power-Up Timer (PWRT) and oscillator start-up timer.
o Low power- high speed CMOS flash/EEPROM.
o Fully static design.
o Wide operating voltage range (2.0 – 5.56)volts.
o High sink/source current (25mA).
o Commercial, industrial and extended temperature ranges.
o Low power consumption (<0.6mA typical @3v-4MHz, 20µA typical @3v-
32MHz and <1 A typical standby).
4.2 IC -7805:
7805 is a voltage regulator integrated circuit. It is a member of 78xx
series of fixed linear voltage regulator ICs. The voltage source in a circuit
may have fluctuations and would not give the fixed voltage output.
The voltage regulator IC maintains the output voltage at a constant
value. The xx in 78xx indicates the fixed output voltage it is designed to
provide. 7805 provides +5V regulated power supply. Capacitors of
suitable values can be connected at input and output pins depending upon
the respective voltage levels.
Fif.4.2.1 IC 7805

MICROCONTROLLER
Pin Description:
Pin
No
Function Name
1 Input voltage (5V-18V) Input
2 Ground (0V) Ground
3 Regulated output; 5V (4.8V-5.2V) Output
Features
• Output Current up to 1 A
• Output Voltages: 5, 6, 8, 9, 10, 12, 15, 18, 24 V
• Thermal Overload Protection
• Short-Circuit Protection
• Output Transistor Safe Operating Area Protection
4.3 Crystal Oscillator:
Fig. 4.3.1symbol of crystal
The Quartz Crystal Oscillator
One of the most important features of any oscillator is its frequency
stability, or in other words its ability to provide a constant frequency output
under varying load conditions. Some of the factors that affect the frequency
stability of an oscillator generally include: variations in temperature, variations
in the load as well as changes to its DC power supply voltage to name a few.

MICROCONTROLLER
To obtain a very high level of oscillator stability a Quartz Crystal is
generally used as the frequency determining device to produce another types of
oscillator circuit known generally as a Quartz Crystal Oscillator, (XO).
.
4.4 Capacitor:
Just like the Resistor, the Capacitor, sometimes referred to
as a Condenser, is a simple passive device that is used to “store electricity”. The
capacitor is a component which has the ability or “capacity” to store energy in
the form of an electrical charge producing a potential difference (Static Voltage)
across its plates, much like a small rechargeable battery.
There are many different kinds of capacitors available from very small capacitor
beads used in resonance circuits to large power factor correction capacitors, but
they all do the same thing, they store charge.
In its basic form, a Capacitor consists of two or more parallel conductive
(metal) plates which are not connected or touching each other, but electrically
separated either by air or by some form of a good insulating material such as
waxed paper, mica, ceramic, plastic or some form of a liquid gel as used in
electrolytic capacitors. The insulating layer between a capacitor plates is
commonly called the Dielectric.
4.5 Resistor:
A resistor is a two-terminal passive electronic component which
implements electrical resistance as a circuit element.

MICROCONTROLLER
Fig.4.5.1 resistor fig. 4.5.1 symbolof resistor
When a voltage V is applied across the terminals of a resistor, a current I
will flow through the resistor in direct proportion to that voltage. This constant
of proportionality is called conductance, G. The reciprocal of the conductance is
known as the resistance R, since, with a given voltage V, a larger value of R
further "resists" the flow of current I as given by Ohm's law:
Table No.

MICROCONTROLLER
4.6 Diode:
Fig.4.6.1 Diode Fig.4.6.2 symbol of diode
In electronics, a diode is a two-terminal electronic component that
conducts electric current in only one direction. The term usually refers to a
semiconductor diode, the most common type today. This is a crystalline piece of
semiconductor material connected to two electrical terminals. the diode is a
device formed from a junction of n-type and p-type semiconductor material.
The lead connected to the p-type material is called the anode and the lead
connected to the n-type material is the cathode. In general, the cathode of a
diode is marked by a solid line on the diode. The primary function of the diode
is rectification
4.7. Relay:
Fig.4.7.1 electromagnetic relay

MICROCONTROLLER
A relay is switch worked by electromagnet .it is useful if we want a small
current in one circuit to control another circuit containing a device such as lamp
or electric motor which requires a large current or if we wish several differential
switch contacts to be operated simultaneously
4.8 CURRENT TRANSFORMER:
CT is a one type of transformer which is used to measure current. It
mostly used in measuring instruments in substation. In this current carrying
conductorpass through a circular corewhich work as a secondarywinding and
conductorwork as primary winding. The Current Transformer ( C.T. ), is a type
of “instrument transformer” that is designed to producean alternating current in
its secondary winding which is proportional to the current being measured in its
primary.
Fig. 4.8.1 current transformer
Current transformers reduce high voltage currents to a much lower value and
provide a convenient way of safely monitoring the actual electrical current
flowing in an AC transmission line using a standard ammeter. The principal of
operation of a current transformer is no different from that of an ordinary
transformer.
4.9 POTENTIAL TRANSFORMER:
Potential Transformer is designed for monitoring single-phase and three-phase
power line voltages in power metering applications.

MICROCONTROLLER
Fig. 4.9.1 potential transformer
The working principle of transformer is very simple. It depends upon
Faraday's law of electromagnetic induction. Actually mutual induction between
two or more winding is responsible for transformation action in an electrical
transformer. Faraday's laws of Electromagnet According to these Faraday's law,
"Rate of change of flux linkage with respect to time is directly proportional to
the induced EMF in a conductor or coil".
4.10 LCD (LIQUID CRYSTAL DISPLAY):
Fig. 4.10.1 LCD display
The values are displayed in the 2x16 LCD modules after converting
suitably. The liquid crystal display (LCD), as the name suggests is a technology
based on the use of liquid crystal. It is a transparent material but after applying
voltage it becomes opaque. This property is the fundamental operating principle
of LCDs.

MICROCONTROLLER
4.11 TRANSISTOR:
Fig. 4.11.1 transistor
A transistor is a semiconductor device used to amplify and switch
electronic signals and electrical power. It is composed of semiconductor
material with at least three terminals for connection to an external circuit. A
voltage or current applied to one pair of the transistor's terminals changes the
current through another pair of terminals. Because the controlled (output) power
can be higher than the controlling (input) power, a transistor can amplify a
signal.

MICROCONTROLLER
CHAPTER: 5
COST OF PROJECT

MICROCONTROLLER
COST OF PROJECT:
SR.NO COMPANENTS NAME QUNTITY
COST/NO.
RS/-
TOTAL
COST
RS/-
1
PIC16F877A
MICROCONTROLLER
1 85 85
2 1 MICRO F CAPASITOR 8 1 8
3 10 MICRO F CAPASITOR 1 15 15
4 22 PF CAPASITOR 8 3 24
5 10 KΩ RESISTOR 17 3 51
8 330 Ω RESISTOR 27 1 27
9 10 KΩ PRESET 1 1 1
10 1 N 4007 DIODE 2 5 10
11 ZENER DIODE 1 5 5
12 RELAY 3 100 300
13
4MHz CRYSTAL
OSCILLATOR
1 15 15
14 BC 548 NPN TRANSISTOR 5 5 25
15 LCD DISPLAY 1 120 120
16 40 PIN IC SOCKET 1 40 40
17
CURRENT
TRANSFORMER
1 150 150

MICROCONTROLLER
18
POTENTIAL
TRANSFORMER
1 150 150
19 PCB 30CM*30CM 1 240 240
TOTAL COST 1355
Table 5.1 cost of project

MICROCONTROLLER
CHAPTER: 6
ADVANTAGES, DISADVANTGES
& APPLICATIONS

MICROCONTROLLER
6.1 Advantages:
 Easy operation
 Lower maintenance cost
 Low power consumption
 High reliability
 Low initial cost
6.2 Disadvantages:
 Skilled personrequired for programming
6.3 Application:
 Used in industries
 Domestic sector
 Power generation, transmission and distribution
 Commercial unit

MICROCONTROLLER
CHAPTER:7
REFERENCE

MICROCONTROLLER
7.1 REFERENCES:
[1] en.wikipedia.org/wiki/Power_factor_correction
[2] Electronics for you magazine
[3] http://www.freescale.com

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