This is our last year diploma project report of Automatic Power Factor Control

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Chapter -1
1.INTRODUCTION
1.1 Introduction
The project is designed to minimize penalty for industrial units by using automatic
power factor correction unit. Power factor is defined as the ratio of real power to apparent power.
This definition is often mathematically represented as KW/KVA, where the numerator is the active
(real) power and the denominator is the (active + reactive) or apparent power. Reactive power is the
non working power generated by the magnetic and inductive loads, to generate magnetic flux. The
increase in reactive power increases the apparent power, so the power factor also decreases. Having
low power factor, the industry needs more energy to meet its demand, so the efficiency decreases.
In this proposed system the time lag between the zero voltage pulse and zero current pulse duty
generated by suitable operational amplifier circuits in comparator mode are fed to two interrupt
pins of the microcontroller. It displays the time lag between the current and voltage on an LCD.
The program takes over to actuate appropriate number of relays from its output to bring shunt
capacitors into the load circuit to get the power factor till it reaches near unity. The microcontroller
used in the project belongs to 8051 family.
The electrical engineering and its applications are the oldest streams of Engineering. Though these
systems are quite reliable and cheaper, it has certain disadvantages. The electro mechanical
protection relays are too bulky and needs regular maintenance. The multifunctional is out of
question. Recently, the technical revolution made embedded technology cheaper, so that it can be
applied to all the fields. The Automatic Power factor Correction device is a very useful device for
improving efficient transmission of active power. If the consumer connect inductive load, then the
power factor lags, when the power factor goes below 0.97(lag) then the Electric supply company
charge penalty to the consumer. So it is essential to maintain the Power factor below with in a limit.
Automatic Power factor correction device reads the power factor from line voltage and line current,
calculating the compensation requirement switch on different capacitor banks.

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1.2 Block Diagram
Fig 1.1 Block Diagram Of Power Factor Improvement
Explanation :
Automatic Power Factor correction device is developed basing on a micro controller 8051. The
voltage and current sampled is converted in to square wave using a zero cross detector. The V and I
sample signals are feed to the micro controller at INT0 and INT1 and the difference between the
arrival of wave forms indicate the phase angle difference. The difference is measured with high
accuracy by using internal timer. This time value is calibrated as phase angle and corresponding
power factor. The values are displayed in the 2x16 LCD modules after converting suitably. The
capacitor banks are switched as per the calibration in steps.

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1.3 Component List
Hardware Software
8051 Microcontroller Keil compiler
switches, slide switches Languages -:
embedded ‘C’ or assembly
relays, relay driver
resistor, capacitor, op-amp, diodes
voltage regulator (zener diode) , crystal
lamp, choke
transformers, shunt capacitors
Table No. 1.1
1.4 Aims Of APFC Panel
Our project is a small model of the automatic power factor improvement device, for
industrial load we can also develop the large capacity power factor improvement device. By
improving the power factor the industrial consumers get the concessions in the energy meter bill.
Also the improvement of power factor helps to decrease the load on the alternator at the generation
station. It is a cheaper and static method of improving power factor. To reduce the losses in the
power system the power factor must be high i.e. at near to unity. This can be achieve by installing
the APFC panel in transmission line and where the inductive loads are in large amount.

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Chapter -2
2. LITERATURE SURVEY
2.1 Literature Survey
We have considered the work done in the previous years, starting from 1988.
Sharkawi et al. proposed a continuing effort to develop an effective, reliable, and inexpensive
adaptive power factor controller (APFC). The APFC was able to compensate adaptively the
reactive power of rapidly varying loads without adding harmonics or transients to the power
system. Based on thousands of hours of field operation, the APFC had substantially modified to
improve its reliability and effectiveness. [1]
Kurachi et al. proposed a detailed analysis of the ripple current of an electrolytic capacitor in a
boost-type power factor control circuit. The ripple current was divided 12 into two components,
namely the low-frequency and the high-frequency components. The root-mean-square value of the
capacitor current was derived for both components. [2]
Tinggren proposed a new integrated power quality device-power factor controller (PFC) for
power distribution system and industrial power circuit applications. A PFC integrated breaker-
switched capacitor banks into a compact design with low cost sensing elements and an intelligent
control unit. The device provided more accurate voltage control and power factor correction than
traditional shunt capacitor bank installations. [3]
Barsoum proposed the programming of PIC micro-controller for power factor correction
that described the design and development of a three-phase power factor corrector using PIC
(Programmable Interface Microcontroller) chip. This involved sensing and measuring the power
factor value from the load using PIC and sensors, then using proper algorithm to determine and
trigger sufficient switching capacitors in order to compensate excessive reactive components, thus
withdraw PF near to unity. [4]
Venkateswarlu, N. proposed a novel compensator, where in-phase and quadrature
components of the supply current are vector-controlled. Implementation of this compensator in a
power electronic system operating with a very poor power factor (and hence high THD) shows that
the system then draws a leading current. A conventional power electronic system with one of the

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traditional static VAR compensators and the conventional power electronic system incorporated
with the proposed
compensator are simulated and the simulation results are obtained. It is shown that the proposed
method offers only 0.7% THD, which also implies that the power factor is improved. [5]
Shuffling presents an intelligent power factor compensation controller that can perform
power factor correction without exciting harmonic resonance under varying demand conditions.
Practical and robust control algorithms are proposed for the purpose of easy implementation in a
micro-controller. In addition, the controller relies on common low cost sensing devices and does
not require additional measurements. As a result, the proposed controller can be constructed as a
retrofitting device to replace existing power factor correction controllers with little effort.
2.2 Theory
POWER FACTOR:
Power factor is the ration between the KW and the KVA drawn by an electrical load where the KW
is the actual load power and the KVA is the apparent load power. It is a measure of how effectively
the current is being converted into useful work output and more particularly is a good indicator of
the effect of the load current on the efficiency of the supply system.
Fig2.1 : Power Factor in Power Triangle
All current will cause losses in the supply and distribution system. A load with a power
factor of 1.0 result in the most efficient loading of the supply and a load with a power factor of 0.5
will result in much higher losses in the supply system. A poor power factor can be the result of
either a significant phase difference between the voltage and current at the load terminals, or it can
be due to a high harmonic content or distorted/discontinuous current waveform. Poor load current
phase angle is generally the result of an inductive load such as an induction motor, power
transformer, lighting ballasts, welder or induction furnace. A distorted current waveform can be the

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result of a rectifier, variable speed drive, switched mode power supply, discharge lighting or other
electronic load. A poor power factor due to an inductive load can be improved by the addition of
power factor correction, but, a poor power factor due to a distorted current waveform requires a
change in equipment design or expensive harmonic filters to gain an appreciable improvement.
Many inverters are quoted as having a power factor of better than 0.95 when in reality, the true
power factor is between 0.5 and 0.75. The figure of 0.95 is based on the Cosine of the angle
between the voltage and current but does not take Apparent power Active power Reactive power
into account that the current waveform is discontinuous and therefore contributes to increased
losses on the supply.

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Chapter -3
3. SYSTEM DEVELOPMENT
3.1 Microcontroller 8051 And Features Of 8051
Pic. 1.1 : MICROCONTROLLER 8051
FEATURES OF MC 8051
 8bit accumulator, 8bit Register and 8bit ALU.
 On chip RAM 128 bites (data memory).
 On chip ROM 4 Kbytes (program memory).
 Two 16bit counter/ timer.
 A 16 bit DPTR (data pointer)
 Two levels of interrupt priority.
 4 byte bi-directional input/ output port.
 Power saving mode (on some derivatives).
 16bit address bus:-it can access 2^16 memory locations:-64kb (65536) each of RAM and ROM.
 It is an inclusion of Boolean processing system, have an ability to allow logic operations to be
carried out on registers and RAM.

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 8bit data bus:-it can access 8bit of data in one operation.
 It also consist of 3 internal and two external interrupts
 UART (this serial communication port makes chip to use simply as a serial communication
interface)
 It has four separate Register set. (Each contains 8 Registers (R0 to R7))
3.2.1 INTERNAL STRUCTURE OF 8051
Fig 3.1: Block Diagram Of Internal structure Of 8051 Microcontroller
 CPU (Central Processor Unit):
As you may be familiar that Central Processor Unit or CPU is the mind of any processing
machine. It scrutinizes and manages all processes that are carried out in the Microcontroller. User
has no power over the functioning of CPU. It interprets program printed in storage space (ROM) and
carries out all of them and do the projected duty. CPU manages different types of registers in 8051
microcontroller.
 Interrupts:
As the heading put forward, Interrupt is a sub-routine call that reads the Microcontroller’s
key function or job and helps it to perform some other program which is extra important at that point

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of time. The characteristic of 8051 Interrupt is extremely constructive as it aids in emergency cases.
Interrupts provides us a method to postpone or delay the current process, carry out a sub-routine task
and then all over again restart standard program implementation.
The Micro-controller 8051 can be assembled in such a manner that it momentarily stops or
break the core program at the happening of interrupt. When sub-routine task is finished then the
implementation of core program initiates automatically as usual. There are 5 interrupt supplies in
8051 Microcontroller, two out of five are peripheral interrupts, two are timer interrupts and one is
serial port interrupt.
 Memory:
Micro-controller needs a program which is a set of commands. This program enlightens
Microcontroller to perform precise tasks. These programs need a storage space on which they can be
accumulated and interpret by Microcontroller to act upon any specific process. The memory which is
brought into play to accumulate the program of Microcontroller is recognized as Program memory or
code memory. In common language it’s also known as Read Only Memory or ROM.
Microcontroller also needs a memory to amass data or operands for the short term. The
storage space which is employed to momentarily data storage for functioning is acknowledged as
Data Memory and we employ Random Access Memory or RAM for this principle reason.
Microcontroller 8051 contains code memory or program memory 4K so that is has 4KB Rom and it
also comprise of data memory (RAM) of 128 bytes.
 Bus:
Fundamentally Bus is a group of wires which functions as a communication canal or mean
for the transfer Data. These buses comprise of 8, 16 or more cables. As a result, a bus can bear 8 bits,
16 bits all together. There are two types of buses:
Address Bus: Microcontroller 8051 consists of 16 bit address bus. It is brought into play to address
memory positions. It is also utilized to transmit the address from Central Processing Unit to Memory.
Data Bus: Microcontroller 8051 comprise of 8 bits data bus. It is employed to cart data.

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3.2.2 PIN DIAGRAM OF MC 8051
Fig 3.2 : Pin Diagram Of MC 8051
Pin-40 : Named as Vcc is the main power source. Usually its +5V DC. You may note some pins are
designated with two signals (shown in brackets).
Pins 32-39: Known as Port 0 (P0.0 to P0.7) – In addition to serving as I/O port, lower order address
and data bus signals are multiplexed with this port (to serve the purpose of external memory
interfacing). This is a bi directional I/O port (the only one in 8051) and external pull up resistors are
required to function this port as I/O.

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Pin-31:- ALE aka Address Latch Enable is used to demultiplex the address-data signal of port 0 (for
external memory interfacing.) 2 ALE pulses are available for each machine cycle.
Pin-30: EA/ External Access input is used to enable or disallow external memory interfacing. If
there is no external memory requirement, this pin is pulled high by connecting it to Vcc.
Pin- 29: PSEN or Program Store Enable is used to read signal from external program memory.
Pins- 21-28: Known as Port 2 (P 2.0 to P 2.7) – in addition to serving as I/O port, higher order
address bus signals are multiplexed with this quasi bi directional port.
Pin 20: Named as Vss – it represents ground (0 V) connection.
Pins 18 and 19: Used for interfacing an external crystal to provide system clock.
Pins 10 – 17: Known as Port 3. This port also serves some other functions like interrupts, timer
input, control signals for external memory interfacing RD and WR , serial communication signals
RxD and TxD etc. This is a quasi bi directional port with internal pull up.
Pin 9: As explained before RESET pin is used to set the 8051 microcontroller to its initial values,
while the microcontroller is working or at the initial start of application. The RESET pin must be set
high for 2 machine cycles.
Pins 1 – 8: Known as Port 1. Unlike other ports, this port does not serve any other functions. Port 1
is an internally pulled up, quasi bi directional I/O port.

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3.3 POWER SUPPLY
Fig 3.3 : Circuit Diagram Of Power Supply
Explanation
The input supply i.e., 230V AC is given to the primary of the transformer(Transformer is
an electromechanical static device which transform one coil to then other without changing its
frequency) due to the magnetic effect of the coil the flux is induced in the primary is transfer to the
secondary coil. The output of the secondary coil is given to the diodes. Here the diodes are connected
in bridge type. Diodes are used for rectification purposes. The out put of the bridge circuit is not pure
dc, somewhat rippled ac is also present. For that capacitor is connected at the output of the diodes to
remove the unwanted ac, capacitor are also used for filtering purpose. The both (-ve) terminal of the
diode (D2 & D3) is connected to the (+ve) terminal of the capacitor and thus the input of the IC
Regulator (7805 & 7812). Here we are using Voltage regulators to get the fixed voltage to our
requirements.” Voltage regulator is a CKT that supplies a constant voltage regardless of changes in
load currents. These IC’s are designed as fixed voltage regulators and with adequate heat sinking can
deliver o/p currents in excess of 1A. The o/p of the IC regulator is given to the LED through
resistors, When the o/p of the IC i.e., the voltage is given to the LED, it makes its forward bias and
thus LED gloves on state and thus the +ve voltage is obtained. Similarly , for –ve voltage ,here the
both +ve terminals of the diodes(D1 & D4) is connected to the –ve terminals of the capacitors and
thus to the I/p of the IC regulator with respect to ground. The o/p of the IC regulator(7912) which is
a –ve voltage is given to the terminal of LED, through resistor, which makes it forward bias, LED
conducts and thus LED gloves in ON state and thus the –ve voltage is obtained.

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TRANSFORMER
1. Main Transformer:
Pic. 1.2 Main Transformer
The main transformer of 230V to 12V step down is used. At the starting of the setup it
is installed for step down the single phase supply voltage 230 volts to 12 volts. The output of this
transformer is given to the diodes, which are connected in bridge style for the rectification purpose.
Also from the transformer primary side the supply is given to the choke which is used
as inductive load and a incandescent lamp which is act as a resistive load in the system.
2. Current Transformer:
Pic . 1.3 Current Transformer
Current transformer reduce the magnitude of the current The current transformer is connected
between the load (inductive) which draws the lagging current and the zero crossing detector which
output is given to the microcontroller.

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3.4 Crystal Oscillator
 The 8051 uses the crystal for precisely that to synchronize it’s operation. Effectively, the
8051 operates using what are called "machine cycles."
 A single machine cycle is the minimum amount of time in which a single 8051 instruction
can be executed. although many instructions take multiple cycles.
 8051 has an on-chip oscillator. It needs an external crystal that decides the operating
frequency of the 8051.
Fig : 3.4 Crystal Oscillator Circuit
3.5 Capacitor Bank
Pic. 1.4: Capacitor Bank
The capacitors are used in the project for the improvement of the power factor which is decreases
due to lagging current drawn by the circuit. In this system four capacitors are used each of4.70µF.

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3.6 LCD
LCD panel consists of two patterned glass panels in which crystal is filled under vacuum.
The thickness of glass varies according to end use. Most of the LCD modules have glass thickness in
the range of 0.70 to 1.1mm.
Pic 1.5 : Liquid Crystal Display
Normally these liquid crystal molecules are placed between glass plates to form a spiral stair
case to twist the twist the light. Light entering the top plate twist 900 before entering the bottom
plate. Hence the LCDs are also called as optical witches. These LCD cannot display any information
directly. These act as an interface between electronics and electronics circuit to give a visual output.
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.
Fig 3.5: Pin Diagram Of LCD

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Pin Description Of LCD
Table 1.2 Pin Description Of LCD
VEE pin is meant for adjusting the contrast of the LCD display and the contrast can be
adjusted by varying the voltage at this pin. This is done by connecting one end of a POT to the Vcc
(5V), other end to the Ground and connecting the center terminal (wiper) of of the POT to the VEE
pin. See the circuit diagram for better understanding.
The JHD162A has two built in registers namely data register and command register. Data
register is for placing the data to be displayed, and the command register is to place the commands.
The 16×2 LCD module has a set of commands each meant for doing a particular job with the display.
We will discuss in detail about the commands later. High logic at the RS pin will select the data
register and Low logic at the RS pin will select the command register. If we make the RS pin high
and the put a data in the 8 bit data line (DB0 to DB7) , the LCD module will recognize it as a data to
Pin No: Name Function
1 VSS This pin must be connected to the ground
2 VCC Positive supply voltage pin (5V DC)
3 VEE Contrast adjustment
4 RS Register selection
5 R/W Read or write
6 E Enable
7 DB0 Data
8 DB1 Data
9 DB2 Data
10 DB3 Data
11 DB4 Data
12 DB5 Data
13 DB6 Data
14 DB7 Data
15 LED+ Back light LED+
16 LED- Back light LED-

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be displayed . If we make RS pin low and put a data on the data line, the module will recognize it as
a command.
R/W pin is meant for selecting between read and write modes. High level at this pin enables read
mode and low level at this pin enables write mode.
E pin is for enabling the module. A high to low transition at this pin will enable the module.
DB0 to DB7 are the data pins. The data to be displayed and the command instructions are placed on
these pins.
LED+ is the anode of the back light LED and this pin must be connected to Vcc through a suitable
series current limiting resistor. LED- is the cathode of the back light LED and this pin must be
connected to ground
Command Function
0F LCD ON, Cursor ON, Cursor blinking ON
01 Clear screen
02 Return home
04 Decrement cursor
06 Increment cursor
0E Display ON ,Cursor blinking OFF
80 Force cursor to the beginning of 1st line
C0 Force cursor to the beginning of 2nd line
38 Use 2 lines and 5×7 matrix
83 Cursor line 1 position 3
3C Activate second line
08 Display OFF, Cursor OFF
C1 Jump to second line, position1
OC Display ON, Cursor OFF
C1 Jump to second line, position1
C2 Jump to second line, position2
Table No. 1.3 LCD commands

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16×2 LCD module has a set of preset command instructions. Each command will make the module
to do a particular task. The commonly used commands and their function are given in the table
below.
INTERFACING OF LCD WITH 8051 MC
Fig 3.6: Interfacing Of LCD with MC 8015
Initialization Of the LCD
 Give the Supply and Wait for a Second to Stabilize the Display.
 Give the Instruction 38h for Initialize 2 Line display of 5*7 Matrix LCD.
 Wait for a few millisecond (approx 5ms) to Complete Operation and LCD take Action as per
given Command.
 Give 0fh Command to Display ON & Cursor ON and Blinking.

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 Wait for some time (approx 5 ms).
 Give command 01h to clear the Display of LCD.
 Wait for some time (approx 5ms).
 Give command 06h for making Increment Cursor mode of LCD. By this, cursor should
increase after every Character is written to display automatically. Wait for some time
(approx 5 ms).
 Give the command 80h for Cursor take position at 1st Line 1st Character.

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3.7 Relay and Relay Driver
 Relay
A relay is an electromechanical switch, which perform ON and OFF operations without any
human interaction. General representation of double contact relay is shown in figure
Generally, the relay consists a inductor coil, a spring (not shown in the figure), Swing
terminal, and two high power contacts named as normally closed (NC) and normally opened (NO).
Relay uses an Electromagnet to move swing terminal between two contacts (NO and NC). When
there is no power applied to the inductor coil (Relay is OFF), the spring holds the swing terminal is
attached to NC contact.
Fig 3.7: Construction Of the Relay
Whenever required power is applied to the inductor coil, the current flowing through the coil
generates a magnetic field which is helpful to move the swing terminal and attached it to the
normally open (NO) contact. Again when power is OFF, the spring restores the swing terminal
position to NC.
Interfacing relay to 8051 microcontroller
There are many ways to interface a relay to 8051 microcontroller. But simple and easy way
for beginners is by using ULN2003/ULN2803. In this tutorial, a 5volts operated relay is taken for
the demonstration. But the circuits shown can be useful to 12Volts operated relays also.

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Why the Relay does not interface directly with the microcontroller 8051?
Generally, a relay takes 70mA (some relays may works with 50mA) current to excite the inductor
coil. But the current sinking capability of each port pin of 89S52/89C52/89C51 has 20mA. So
whenever 70mA current flow into the port pin may cause damage to that particular port pin. So to
avoid this problem we need a large current sinker.
WHAT IS THE NEED OF ULN2803/ULN2003?
As we discuss above we need a large current sinker circuit between the relay and 8051
microcontroller. A transistor which has current sinking capability greater that 70mA is enough to
act as a relay driver between the microcontrollers and relay. But the biasing circuit required for the
transistor is a bit clumsy. In some cases like robotic car, the number of relays required will
increase. Therefore the number of transistors and its biasing components will increase, PCB size
increases, debugging is a bit headache.
 Relay Driver ULN 2003
The circuit used for driving a relay can be termed as a relay driver circuit and it can be designed
using various integrated circuits. These relays are needed to be driven for activating or to turn ON.
So, relays require some driver circuitry to turn ON or OFF (based on the requirement).The relay
driver circuit can be realized using different integrated circuits.
Fig 3.8: Pin Description of Driver ULN 2003

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The IC ULN2003A is a Darlington transistor array which deals with high-voltage and
high-current. There are various types of relay driver ICs such as a high side toggle switch, low side
toggle switch, bipolar NPN transistor, Darlington transistor, N-channel MOSFET, ULN2003 driver
IC.
Pin No Function Name
1 Input for 1st channel Input 1
2 Input for 2nd channel Input 2
3 Input for 3rd channel Input 3
4 Input for 4th channel Input 4
5 Input for 5th channel Input 5
6 Input for 6th channel Input 6
7 Input for 7th channel Input 7
8 Ground (0V) Ground
9 Common freewheeling diodes Common
10 Output for 7th channel Output 7
11 Output for 6th channel Output 6
12 Output for 5th channel Output 5
13 Output for 4th channel Output 4
14 Output for 3rd channel Output 3
15 Output for 2nd channel Output 2
16 Output for 1st channel Output 1
Table No. 1.4: Pin Description Ofrelay driver ULN 2003

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 Interfacing Of Relay to microcontroller 8051 through relay driver ULN 2003
Fig 3.9 Interfacing Of Relay to microcontroller 8051 through relay driver ULN 2003
The simple way to drive the relay with 8051 microcontroller is by using ULN2003/ULN2803. A
ULN driver has 500mA current sinking capability for each output pin. When input pin of ULN
driver is at logic high then the corresponding output pin is connected to ground via 500mA fuse.
Internally each fuse is designed by using Darlington transistor pair. So interfacing the 8051
microcontroller to relay via ULN driver will not damage the microcontroller port pin. The
interfacing circuit is shown in figure.

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WHAT IS THE NEED OF FLY WHEEL DIODE?
When power is applied to the relay inductor coil the current flowing through it causes magnetic
field energy stored in it. This magnetic field is stored through the center of the coil and also outside
of the coil.
B = LI2/2.
When the current flowing through inductor is off (i.e., the current changes from max to
zero) causes changes in the stored magnetic field which in turn produce electric field that opposes
the change in the current.
V = Ldi/dt.
If the current change is fast, the derivative value will be very high. The voltage produced
due to the electric field across the coil to opposite to the actual current direction (i.e., negative
potential) and may reach hundreds of volts if the change in current is very fast. This large voltage
may damage the electronic parts.
Figure 3.10: Inductor coil connected across the collector terminal
As shown in figure 1.8 the inductor coil is connected at the collector terminal of the transistor.
When logic high is applied, the transistor is in ON state, so the current flows along the inductor and
transistor. When a logic LOW is applied, the transistor enters into OFF state (OPEN circuit), which
in turn stop the current flow. Inductor doesn’t allow sudden changes in the current therefore large
negative voltage is produce across inductor coil and causes electrons to cross the air gap as shown
in figure. Therefore an electric spark/arc is produced across the open terminals of the transistor and
it may damage the transistor as shown in figure 1.9

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Figure 3.11 Spark Generated when inductor coil current is suddenly off
To avoid such problem, place a diode across the inductor coil as shown in below figure. When a
power of the coil is OFF, the electric field (produced from the stored magnetic field) finds a path to
flow electrons. Therefore the stored energy dissipates in the diode. When the relay coil power is
ON, then the diode is not in conducting state. Whenever the power is OFF, the voltage appears
across coil forward bias the diode and the current find a path to flow as shown in figure 1.11
Figure 3.12 Flywheel diode across the inductor coil protects the transistor

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3.8 Zero Crossing Detectors(ZCD)
The zero crossing detector is a sine-wave to square-wave converter. The reference voltage
in this case is set to zero. The output voltage waveform shows when and in what direction
an input signal crosses zero volt. If input voltage is a low frequency signal, then output
voltage will be less quick to switch from one saturation point to another. And if there is
noise in between the two input nodes, the output may fluctuate between positive and
negative saturation voltage Vsat. .Here IC 339N is used as a zero crossing detector.

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Chapter-4
ALGORITHM OF THE PROJECT
(a)Altering phase of two signals
Step-1:- Timer0 set and run till Timer1 is set or vice-versa.
Step-2:- Two signals (current & voltage) are introduced.
Step-3:- Phase angle between the two signals altered by incrementing or
Decrementing delay between two.
Step-4:- Delay of 0.1 ms is given while incrementing or decrementing.
Step-5:- Accumulator stores the number of incrementing or decrementing operations.
Step-6:- Delay is called according to the number stored in the accumulator.
Step-7:- The signals, altered in phase are sent to the motherboard for power factor detection.
(b) Phase angle Detection:
Step-1:- Microcontroller started on interrupt mode.
Step-2:-INTX0 & INTX1 are enabled.
Step-3:-INTX0 given VOLTAGE (V), INTX1 given CURRENT (I) from sampling circuit.
Step-4:-Timer measures time interval between two interrupts.
Step-5:-Time interval calibrated .
Step-6:-Calibrated data is converted from HEX to BCD, then to ASCII for display on LCD.

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4.2 Component List
Sr. No. COMPONENT NOS.
1. Transformer 2
2. P-N junction Diodes 8
3. 2.50Mf capacitors 4
4. schottky barrier rectifier 2
5. Voltage Regulator 2
6. 470 µf capacitor 1
7. total resistors 20
8. LEDs 5
9. Relays 4
10. slide switches 2
11. ZCD (voltage & current) 2
12. 10 µf capacitors 2
13. Relay driver 1
14. Microcontroller 8051 1
15. LCD 1
16. Incandescent Lamp 1
17 Choke 1
18. Lamp Holder 1

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19 PCB 1
Table No 1.5: Component List
At the time of making of project kit other accessories are also required for
installing the components on the PCB like soldering gun, tester, etc. For making the
program we used Keil software and assembly language. The microcontroller 8051 used
because it is studied in last semester and also it is a cheaper microcontroller. Plywood is
used for give the support to entire structure and also give protection for handling.
The schottky barrier rectifier is used for give the protection against the
reverse voltage which may damage the rectifier, filter and comparator circuit also.
Total Cost of Project
2500/- to 3500/- only

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Chapter -5
PERFORMANCE ANALYSIS
Advantages, Disadvantages and Applications
 Advantages OF Improved Power Factor
Reactive power decreases
Avoid poor voltage regulation
Overloading is avoided
Copper loss decreases
Transmission loss decreases
Improved voltage control
Efficiency of supply system and apparatus increases
 ADVERSE EFFECT OF OVER CORRECTION:
 Power system becomes unstable
 Resonant frequency is below the line frequency
 Current and voltage increases
 APPLICATIONS OF POWER FACTOR
Our project is a model of static power factor correction method. By increasing the capacity
and the ratings of the components it can be used for the following purpose------
1. In industries
2. At substations
3. on the transmission line
4. for commercial purpose

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Chapter -6
IMPLEMENTATION AND RESULT
6.1 Conclusion
It can be concluded that power factor correction techniques can be applied to the industries,
power systems and also house holds to make them stable and due to that the system becomes stable
and efficiency of the system as well as the apparatus increases. The use of microcontroller reduces
the costs. Due to use of microcontroller multiple parameters can be controlled and the use of extra
hard wares such as timer, RAM,ROM and input output ports reduces. Care should be taken for
overcorrection otherwise the voltage and current becomes more due to which the power system or
machine becomes unstable and the life of capacitor banks reduces.
6.2 Problem Encountered
 While soldering some contacts are short circuited . So we disorder the connection and did
soldering again.
 A leg of the microcontroller was broken before the dumping of program, we brought
another microcontroller and install it.
 A lamp holder is broken during the fitting it on the plywood we brought another and fit it.
6.3 Future Improvement
 In my project, I used the assembly language program to operating the microcontroller 8051
and all other related components. We can also use the Aurdino for this project to make the
advanced. In future days in many applications Aurdino is used .
 Currently we uses microcontroller 8051, the use of another MC can make the system
advanced.
 By changing the program we can obtain the other advanced features or the LCD will be
showing other parameters present in the system for different applications.
6.4 Recommendation
It is highly recommended that this system of high capacity should be installed at every
industry, commercial buildings an also in a transmission system where the power factor is
continuously poor.

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 COMPLETE HARDWARE

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REFERENCES
Books
1. Shakawi et al. 1988
2. Kurachi et al. 1995
3. Barsoum 2007
4. Tinggren 1999
5. Venkateshwarlu, N.2011
6. Power System Engineering - Dhanpatrai Publications ltd.
7. The 8051 Microcontroller -Penram International
8. Power factor correction handbook
9. Power factor correction- John ware
Websites
1. www.electrical4u.com
2. www.switchgearpanels.com
3. www.atmel.com
4. microcontrollerslab.com
5. ieeeexplore.ieee.org
6. freebookcenter.net
7. en.wikibooks.org

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