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POKHARA UNIVERSITY SCHOOL OF ENGINEERING

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

Proposal On

POWER SAVER FOR INDUSTRIES AND COMMERCIAL ESTABLISHMENTS

Prepared By:

Bishworna Basnet (066/BEE/009)

Dil Bahadur Ale (066/BEE/010)

Krishna Ale (066/BEE/015)

Sunil Gurung (066/BEE/045)

Submitted to:

Ass. Pro. Lalit Bikram Rana

Department of Electrical and Electronics Engineering

P.U.

28-May-2013

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ACKNOWLEDLEDMENT

As per the course code PRJ 400.5 of electrical and electronics department, we are going

to perform the Final year project on “POWER SAVER FOR INDUSTRIES AND

COMMERCIAL ESTABLISHMENTS”. With this project we are supposed to be familiar with

the various aspects and concepts of power systems in industries and its control

mechanism, power loss and power factor improvement, interfacing with microcontroller

(8051) for displaying power loss due to inductive loads. During this project, we expect

the continuous assistance from our supervisor and all related lectures. We are supposed

to complete our project successfully with their assistance and hope to increase our

ability in power engineering.

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ABSTRACT

We are facing an acute shortage of electrical power these days, every now and then

there is a power cut in some part of our city. If we could save some power from our

house and industries, it could be utilized somewhere else, it could be a good

contribution towards national development process. This project is designed to reduce

the power loss in industries by power factor compensation through number of shunt

capacitors. It is achieved by engaging number of shunt capacitors in parallel to inductive

loads as per the requirements. The time lag between zero voltage and zero current is

fed to the microcontroller (8051) that drives relays from its output for bringing shunt

capacitor across the load till the power factor reaches to 0.9. This saves lot of power

and thus reduces the electric bill in industries and commercial establishments.

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Contents

Description Page No.

Acknowledgement………………………………………………………………………..1

Abstract………………………………………………………………………………………..2

Introduction

Background……………………………………………………………………….4

Motivation…………………………………………………………………………5

Objectives…………………………………………………………………………5

Methodology…………………………………………………………...………………….5

Block Diagram……………………………………………………………………………..6

System Overview………………………………………………………………………….7

Literature Survey

Power factor………………………………………………………………………8

Power factor correction………………………………………………………8

Supply Harmonics………………………………………………………………..9

Gantt chart……………………………………………………………………………………..10

Conclusion……………………………………………………………………………………….11

References………………………………………………………………………………………12

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INTRODUCTION

Background

Establishment of factories is the one of essential part of the nation. Proper and well

managed factories and commercial establishment rises up the economic sector as well

as the international rank of the nation. We require high amount of electricity for that

although we are in the grip of electricity crisis. It is profitable and advantageous if we

are able to minimize the consumption of electricity in the industries and reduce the

electricity crisis, load shedding somehow and the amount of bill for electricity. Since

requirement of high amount electricity is due to the low power factor of the system.

Our objective is to increase the power factor of the system thus by reducing the amount

of electricity required.

Almost all of the equipment in factories is inductive in nature where current is being

lagging with the voltage. An industrial load such as induction motors, an arc and

induction furnace, fluorescent tubes, fans, lighting ballast, welder, etc. normally

operates at low power factor. All these inductive loads working at low power factor

need large amount of reactive power which results in reduced voltage level at the load

terminals. A low voltage at the consumer terminals is undesirable as it leads to low

performance of the utility devices. So for better performance of the utility devices and

for saving the energy or power, the system power factor improvement must be done.

There are various methods for the improvement of power factor though we use shunt

capacitor method for its simplicity, reliability and availability. Capacitor banks are

connected across the load. Since the capacitor takes leading reactive power, overall

reactive power taken from source decreases, consequently system power factor

improves. By using the capacitor banks parallel with the inductive loads the system

efficiency can be increased by 99.6 % where the loss is less than 1/2 %. Capacitor is a

leading power factor device; hence it overcomes the lagging of machines, reducing the

power angle.

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Motivation

The concept of POWER SAVER as a final year project was developed based on the

existing energy crisis in Nepal. A lot of electrical power is consumed by industries. If we

can save some power in industries, it can help in minimizing the loadshedding as well as

minimizing the electricity bill.

Objectives

The main objectives of our project are:

Reducing the power loss in industries by power factor compensation

through number of shunt capacitors

Displaying the power loss due to inductive load on the LCD by using the 8

bit microcontroller 8051

METHODOLOGY

For the successful design and systematic running of this project, following different

methods will be adopted:

Literature survey

Designing

Writing Algorithm

Codding & Burning

Simulation

Testing

Analysis

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BLOCK DIAGRAM

Figure 1: Block Diagram of power saver

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SYSTEM OVERVIEW

Power factor is the cosine of angle between the voltage and current in the AC circuit. It

can be defined as the ratio of active power to the reactive power. Mathematically,

( )

( )

Reactive power is the non-working power generated by inductive load. So smaller the

reactive component of power, smaller the phase angle and higher the power factor. In

inductive load, current lags the voltage where as in the capacitive load, current leads the

voltage. If device drawing leading power (i.e. capacitor bank) is connected in parallel

with inductive load, the lagging reactive power of the load will be partly neutralized,

resulting in improvement of the power factor.

Having low power factor in industries means drawing more energy to meet its demand,

decreasing the efficiency of the system. So to reduce the power loss shunt capacitors

are used as shown in block diagram. In this system the time lag between the zero

voltage pulse and zero current pulse duly generated by the suitable operational

amplifier circuit in comparator mode are fed to two interrupt pins of the

microcontroller. Microcontroller displays the power loss due to the inductive load on

the LCD. The program takes over to actuate appropriate number of relays at its output

to bring shunt capacitors into the load circuit to get zero power loss.

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LITERATURE SURVEY

Power factor

Power factor is the ratio between the KW and the KWA drawn by electrical load. KW is

the active power and KWA is the reactive power of the system. It is measure of how

effectively the current is being converted into useful work.

Apparent power

Reactive power

Active power

Fig. Power Diagram

All current causes losses in the supply and distribution system. Load with power factor

1.0 is the most efficient loading of the supply and load with power factor 0.5 will result

in much higher losses in the supply system. Poor power factor can be the result of either

a significant phase difference between voltage & current or distorted/discontinuous

current waveform. Distorted current waveform is result of a rectification, variable speed

drive, switched mode power supply, discharged lighting or other electronic loads.

Power factor correction

Power correction can be done by using static capacitor and by using synchronous

condenser. Here in this project we are using the static capacitor method. Shunt

capacitors are placed across the load and can be applied at the switch board or

distribution panel. Leading current cancels the lagging inductive current flowing from

the supply.

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Fig. Circuit and Phasor Diagram

The rating of the capacitor can be calculated as

Therefore

Supply Harmonics

Harmonics is caused by nonlinear loads. It causes high current flow in the capacitors.

High current flow will cause heating of capacitors and reduces its life. These harmonics

can be reduced by harmonic compensators.

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GANTT CHART

Fig. Gantt chart

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Conclusion

The final product of our project is done on PCB board and is demonstrated with fully

functioning electronic circuit. The final product is supposed to represent the design

concept of our project. The same concept can be utilized to design other power saving

devices. But there will be always a space for its improvements. No matter what the

performance of the system, anyone who has little technical knowledge can become

familiar with this product. After completion we hope the device to be beneficial for the

industries as well for the domestic uses for saving power and reducing the electricity bill

and loadshedding.

A successful completion of this project is expected, since each of the project members

will be working very hard for it and will be trying to make this product better in every

possible way. For this a constant guidance and help from the supervisor and lecturers is

expected. In the course of construction of the POWER SAVER an immense knowledge on

the industrial system and its challenges on the power factor correction are supposed to

be acquired.

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References:

Ashfaq Husain, “Fundamental of Electrical Engineering”

J.B. Gupta, “A Course in Electrical Power”

Dr. P.S. Bimbhra, “Power Electronics”

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