UNIVERSITY OF NAIROBI. SCHOOL OF …eie.uonbi.ac.ke/sites/default/files/cae/engineering/eie/POWER...

PROJECT 71: POWER LINE DATA TRANSMISSION FOR A SMART METERING HUB BY:F17/30303/2009

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UNIVERSITY OF NAIROBI.

SCHOOL OF ENGINEERING.

DEPARTMENT OF ELECTRICAL AND INFORMATION ENGINEERING.

PROJECT INDEX: PRJ 71.

POWER LINE DATA TRANSMISSION FOR A SMART METERING HUB.

By

OGWENO ORNYX KIMASA.

F17/30303/2009.

Supervisor: Prof. MWANGI MBUTHIA.

Examiner: Mr. PETER MUSAU.

A Project report submitted in partial fulfillment of the

requirements for the award of the degree

Of

Bachelor of Science in ELECTRICAL AND ELECTRONIC ENGINEERING of the

University Of Nairobi.

Submitted on: April 24, 2015.


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DECLARATION OF ORIGINALITY.

NAME OF STUDENT: OGWENO ORNYX KIMASA

REGISTRATION NUMBER: F17/30303/2009

COLLEGE: Architecture and Engineering

FACULTY: Engineering

DEPARTMENT: Electrical and Information Engineering

COURSE: Bachelor of Science Electrical & Electronic Engineering

TITLE OF THE WORK: Power line Data Transmission for a Smart Metering Hub.

1) I understand what plagiarism is and I am aware of the university policy in this regard.

2) I declare that this final year project is my original work and has not been submitted

elsewhere for examination, award of degree or publication. Where other people‟s work or

my work has been used, this has properly been acknowledged and referenced in

accordance with the University of Nairobi‟s requirements.

3) I have not sought or used the services of any professional agencies to produce this work.

4) I have not allowed, and shall not allow anyone to copy my work with the intention of

passing it off as his/her own work.

5) I understand that any false claim in respect of this work shall result in disciplinary action,

in accordance with the university anti-plagiarism policy

Signature……………………………………………………………………………………….

Date……………………………………………………….…………………………………….


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DEDICATION.

This project is dedicated to My Loving Parents Mr. and Mrs. Ogweno, for their effort to ensure I pursue

my dream career in Electrical and Electronic Engineering.


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ACKNOWLEDGEMENT.

First and foremost, I wish to thank the almighty God for guiding me and being on my side

throughout my studies.

Over the years, many people have helped me to become acquainted with the various topics I have

learned that have brought me this far. While it is impossible to list all their names, I do remember and

fully appreciate their contributions.

On a personal note, I would like to thank Prof. MWANGI MBUTHIA of the department of Electrical

and Electronics Engineering for taking time to offer cogent suggestions towards accomplishing the

project objective. I also greatly appreciate the efforts and contributions made by the laboratory

technicians in the department.


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ABSTRACT.

Power line communication is one of the emerging technologies used in an effective and high speed

communication of data.

It has been used successfully in many real time applications. The paper proposes data transmission for

Smart Meter Reading to a Smart Metering Aggregator at the rate of 2400 kbps, replacing manual “man”

meter reading. The system uses existing power lines of 240 V/ 50 Hz to send data from a Smart Meter to

a Smart Metering Aggregator.

Data transmission over AC power lines is set to turn the largest existing network in the world, the

electricity distribution grid or hub, into a data transmission network hub resulting into a communication

hub.


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TABLE OF CONTENTS. DECLARATION OF ORIGINALITY. ............................................................................................................................... i

DEDICATION. ............................................................................................................................................................ ii

ACKNOWLEDGEMENT. ............................................................................................................................................ iii

ABSTRACT. .............................................................................................................................................................. iv

TABLE OF CONTENTS. .............................................................................................................................................. v

LIST OF FIGURES. .....................................................................................................................................................vii

LIST OF TABLES. ...................................................................................................................................................... viii

ABBREVIATION. ........................................................................................................................................................ix

CHAPTER ONE. ......................................................................................................................................................... 1

INTRODUCTION. ................................................................................................................................................... 1

CHAPTER TWO. ........................................................................................................................................................ 3

LITERATURE REVIEW. ........................................................................................................................................... 3

2.1. BACKGROUND. ............................................................................................................................................. 3

2.2. PROJECT OBJECTIVE. .................................................................................................................................... 3

2.3. COMPARISON AND EVALUATION OF COMMUNICATION PROTOCOLS. ........................................................ 3

2.3.1 X-10. ............................................................................................................................................................ 3

2.3.2 CEBUS TECHNOLOGY................................................................................................................................... 5

2.3.4 POWER LINE DATA TRANSMISSION. ........................................................................................................... 7

2.3.4 i). APPLICATIONS OF DATA TRANSMISSION OVER POWER LINES. ........................................................... 7

2.3.4 ii) COMMUNICATION TECHNIQUES. ........................................................................................................ 9

2.3.4 iii) CLASSIFICATION OF POWER LINE DATA TRANSMISSION. ................................................................. 11

2.3.4 iv) DIRECTIONS OF DATA TRANSMISSION. ........................................................................................... 12

2.3.4 v) CHALLENGES IN THE POWER LINE NETWORK. .................................................................................. 13

2.4. IMPEDANCE AND TRANSFER FUNCTION. ................................................................................................... 15

2.5. PROBLEM DEFINITION. ............................................................................................................................... 16

2.5.1 Requirements. ....................................................................................................................................... 17

2.5.2 Solution of the problem. ....................................................................................................................... 17

CHAPTER THREE. .................................................................................................................................................... 19

3.1. INTRODUCTION. .......................................................................................................................................... 19

3.2. CIRCUIT DESIGN. ......................................................................................................................................... 20

3.2.1 HCPL-800J. ............................................................................................................................................ 21

3.2.2 TRANSMITTER POWER ISOLATION CIRCUIT. ......................................................................................... 23


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3.2.3 RECEIVER POWER ISOLATION CIRCUIT. ................................................................................................. 25

3.2.4 Power Line Isolation Circuit. .................................................................................................................. 26

3.2.5 Power Supply. ....................................................................................................................................... 27

3.3. PRINTED CIRCUIT BOARD LAYOUT. ............................................................................................................. 28

3.4. THE CIRCUIT BUILT. ..................................................................................................................................... 30

CHAPTER FOUR. ..................................................................................................................................................... 32

RESULTS AND ANALYSIS. .................................................................................................................................... 32

4.1 SIMULATED RESULTS. ............................................................................................................................... 34

4.2 PRACTICAL RESULTS. ................................................................................................................................ 35

CHAPTER FIVE. ....................................................................................................................................................... 37

5.1. CONCLUSION. .............................................................................................................................................. 37

5.2. RECOMMENDATIONS. ................................................................................................................................. 38

REFERENCES. .......................................................................................................................................................... 39

APPENDICES. .......................................................................................................................................................... 40

Appendix 1: HCPL-800J IC Data sheet. ............................................................................................................... 40

Appendix 2: Voltage regulator 78L05 Data sheet............................................................................................... 40

Appendix 3: Varistor Data sheet. ....................................................................................................................... 40

Appendix 4: Cost analysis ................................................................................................................................... 40


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LIST OF FIGURES.

Figure 1.1: Power Line Data Transmission (PLDT)………………………………………………………………..……………………………….2

Figure 2.1: Representation of the X-10 signal……………………………………………………………………………………………………….4

Figure 2.2: Digital Communication Techniques and their Expressions…………………………………………………………….….11

Figure 2.3: Directions of Data Transmission……………………………………………………………………………………………………….12

Figure 2.4: Smart Meter Reader System Block Diagram………………………………………………………………..……………………18

Figure 3.1: HCPL-800J CHIP……………………………………………………………………………………………………………………….……….19

Figure 3.2: Circuit Block Diagram……………………………………………………………………………………………………………………....20

Figure 3.3: Internal Block Diagram of the HCPL-800J IC ……………………………………………..………………………………….…..21

Figure 3.4: HCPL-800J Package Pin Out……………………………………………………………………………….………………………….….22

Figure 3.5: Transmitter Power Isolation Circuit Schematic Circuit……………………………………………………………………...24

Figure 3.6: Band Pass Filter Circuit……………………………………………………………………………………………………………………..24

Figure 3.7: Receiver Power Isolation Circuit Schematic Circuit…………………………………………………………………………..25

Figure 3.8: LC Coupling Circuit. ………………………………………………………………………………………………………….……………..27

Figure 3.9: Power Supply circuit………………………………………………………………………………………………………………………..27

Figure 3.10: PCB Layout…………………………………………………………………………………………………………………………………….28

Figure 3.11: Circuit Built…………………………………………………………………………………………………………………………………….30

Figure 4.1: Transmitter power isolation circuit connection side………………………………………………………………………..32

Figure 4.2: Receiver power isolation circuit connection side……………………………………………………………………………..33

Figure 4.3: Input and Output result on Proteus………………………………………………………………………………………………….34

Figure 4.4: LC filter result on Proteus…………………………………………………………………………………………………………………34

Figure 4.5: Input from the Signal Generator at 132 KHz……………………………………………………………………………………..35

Figure 4.6: Output displayed on Oscilloscope, at 132 KHz………………………………………………………………………………….36


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LIST OF TABLES.

Table 2.1: Two packets of the X-10 protocol……………………………………………….………………………………………………4

Table 2.2: Table of the different channels that support the LonTalk protocol…………….…………………………..….6

Table 3.1. Pin Descriptions…………………………………………………………………………………………………………..…………….22

Table 5.1. Bill of Quantities…………………………………………………………………………………………………………………………40


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ABBREVIATION.

AM: Amplitude Modulator.

AC: Alternating Current.

ASK: Amplitude Shift Keying.

CEBus: Consumer Electronics Bus.

HDR: High data Rate.

FM: Frequency Modulator.

FSK: Frequency Shift Keying.

FCC: Federal Communication Commission.

GSM: Global System for Mobile Communication.

GPRS: General Packet Radio Service.

LAN: Local Area Network.

LDR: Low Data Rate.

SMR: Smart Meter Reader.

PLDT: Power Line Data Transmission.

PSK: Phase Shift Keying.

QPSK: Quadrature Phase Shift Keying.

ZVCP: Zero-Voltage Crossing Point.


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CHAPTER ONE.

INTRODUCTION.

Energy saving is more important in recent time. This requires the intelligent distribution,

monitoring and managing of the energy. This solution is made possible by Smart Meter Reading

(SMR) which means automatic communication between two points over a distance.

In this way consumption of water, gas and energy can be remotely monitored, measured and

controlled. This is in contrast with the manual meter reading, which is based on people hired to

collect the data from the meters which are prone to error and low efficiency. Electricity is

consumed in everything we do and it has become synonymous with life in the environment we

live in. Communications, transport, food supplies, and most amenities in our surrounding e.g. in

homes, offices and factories depend on a reliable supply of electrical power.

Smart Meter Reading (SMR) requires a device to collect the data and to send it to a Smart

Metering Aggregator. This device connects all the meters to the Smart Metering Aggregator

resulting into a Communication Hub. It can be unidirectional, from the smart meters to a central

gateway or bidirectional which adds managing capabilities, such as connecting/disconnecting

users, collecting data from the smart meters according to certain rules, grouping the smart

meters. The communication support consists of physical wires or wirelessly by GSM module.

The wired solution can be implemented with distinct wires, based on power lines which are an

already existing device. The use of power lines for carrying data is efficient for both financial

and energetic point of views. This solution is known as Power Line Data Transmission (PLDT).


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Figure 1.1: Power Line Data Transmission (PLDT).

a)

b)


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CHAPTER TWO.

LITERATURE REVIEW.

2.1. BACKGROUND.

Data transmission is a key element in the world as a communication aspect, hence the need to

automate the various method of data transmission between two points. Today‟s technology has

evolved to be as smart as simulation games on computers. Smart meters can be literally

programmed to execute pre-defined and real time, instructions on a specific time of the day,

week, or month, resulting in a high speed transfer of data of 2400 kbps from two or more points.

2.2. PROJECT OBJECTIVE. To implement data transmission over a power line to transfer data at a rate of 2400 kbps from a

smart meter to a smart metering data aggregator.

2.3. COMPARISON AND EVALUATION OF COMMUNICATION PROTOCOLS. Research in the technology domain supporting PLDT led to the emergence of different protocols

describing the modulation scheme used, the data transmission rate, the drawbacks, the relative

cost and the target applications, below is some discussion on different kind of protocols?

2.3.1 X-10.

The most ancient communication protocol used in networking.

It was developed by the X-10 US Corporation and used to allow compatible devices to

communicate with each other over 240V AC wiring.

Protocol description.

X-10 simply provides the technical specifications of how a device should place a signal onto the AC

power line. The X-10 technology transmits binary data using the amplitude modulation technique.

To differentiate the data symbols that the carrier uses is the zero-voltage crossing point (ZVCP) of

the 60 Hz on the negative or the positive cycle hence for synchronization purposes, the presence of a

120 kHz signal burst at the zero crossing indicates the transmission of a binary one, whilst the

absence of the 120 kHz signal indicates a binary zero as shown in figure 2.1.


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Figure 2.1: Representation of the X-10 signal.

To prevent device clash X-10 uses a detailed addressing scheme to achieve. Devices contain two

addresses - a house address, and an individual device address. A typical X-10 transmission

would include a start code, house address, device address and the function code.The X-10 system

is limited in that it does not easily provide for two-way communications and is very slow,

although adequate for simple home automation tasks. Every bit requires a full 60 Hertz cycle and

thus the X-10 transmission rate is limited to only 60 bps. Usually a complete X-10 command

consists of two packets with a 3-cycle gap between each data packet. Each packet contains two

identical messages of 11 bits each.

Table 2.1: Two packets of the X-10 protocol.

Start Code House Code Number Code Start Code House Code Number Code

Code transmitted when a number button is pressed

Start Code House Code Function Code Start Code House Code Function Code

Code transmitted when a function button is pressed


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Disadvantages.

The X-10 technology would not fit my project design for the main fact that it has limited potential in

speed and intelligence terms. Its low data rate and undeveloped functionality permit to use the X-10

technology in limited applications. In addition to its unreliability of amplitude modulation and error

correction, X-10 operates on 240 V AC, which is a major drawback to its use.

2.3.2 CEBUS TECHNOLOGY.

Consumer Electronics Bus (CEBus), a standard proposed by the Electronic Industries

Association, is based on the concept of Local Area Networks (LAN‟s). CEBus based products

consist mainly of a transceiver which implements spread spectrum technology along with a

controller to run the protocol. The given protocol standards are for radio frequency, twisted pair,

power line communication and a number of other networking methods. The CEBus standards

specifies that a binary digit is represented by how long a frequency burst is applied to the

channel i.e., a binary „1‟ is represented by a 100 microsecond burst, whilst a binary „0‟ is

represented by a 200 microsecond burst. The transmission rate varies with how many „0‟

characters, and how many „1‟ characters are transmitted. The CEBus standard specify a

language of object oriented controls including commands for volume up/down, temperature up

one degree, etc. Due to the high noise level of power line channels, it is recommended that data

should be transmitted via short frames, which is assured by the use of the spread spectrum

technology. CEBus protocol uses a Carrier Sense Multiple Access/Collision Detection and

Resolution (CSMA/CDCR) protocol to avoid data collisions. CEBus is a commercially owned

protocol, and thus attracts registration fees.

2.3.3 LONWORKS TECHNOLOGY.

This technology was developed by Echelon Corporation. It is essentially structured as an

automatic control system that consists of sensors, actuators, application programs,

communication networks, human-machine interface and network management tools.

LonWorks (Local Operation Networks) technology is an important new solution for control

networks developed by Echelon Corporation. Control network is any group of devices working

in a peer-to-peer fashion to monitor the different components cited above. It can control and link

factory conveyor belts, product inventory, and distribution systems for optimum efficiency and


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flexibility. Smart office buildings can turn lights on and off, open and lock doors, start and stop

elevators, and connect all functions to a central security system

The LonTalk communications protocol is a layered, packet-based, serial peer-to-peer

communications protocol. This protocol is designed for the requirements of control systems,

rather than data processing systems. Also, LonTalk protocol is media-independent that allows the

system to communicate over any physical transport media. LonTalk has been approved as an

open industry standard by the American National Standards Institute

Power lines are a possible medium that LonWorks devices could be attached to. The data rate

will then be 5 kbps, obviously there is no limit to the number of devices that could be connected

to the system.

Applications of Lon Works:

Automated supermarket pricing

Avionics instrument integration

Circuit board diagnostics

Electronic locks

Intelligent industrial I/O irrigation management

Lighting control

Power supply management

Research experiment monitoring.

Table 2.2: Table of the different channels that support the LonTalk protocol.

Channel type Data rate Medium Max. Devices Max. Distance

PL-20 5000kbps Power line No limit Determined by

attenuation

TP/Xf-78 78kbps Twisted pair,bus 64 1330m(bus

length)

TP/Xf-10 78kbps Twisted

pair,flexible

topology

64 500m(node-

node)

TP/Xf-1250 1.255Mbps Twisted pair,bus 64 125m(bus length)


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2.3.4 POWER LINE DATA TRANSMISSION.

PLDT is the art of sending data through power lines.

The process involves three steps:

1. Modulation of the signal to be sent over the transmission medium.

2. Transmit the signal in such a manner to reduce signal distortion.

3. Receive and demodulate the signal to extract the data.

Electricity providers are turning to Power line data transmission for the readings of the smart

meters to relieve the stress on the exhausted power grids. Energy providers do not want to build

more complex grids which are expensive to build, instead, they would like to focus their time

and money into more efficient and long-term solutions as Power line Data Transmission. PLDT

systems can be implemented to supply the providers with information on how the consumer

utilizes the energy, assist in accurate billing and information needed at any moment. PLDT

systems can also be used between many utility companies to sell and buy excess generated

power when needed. Thus PLDT systems involve communication between two parties.

2.3.4 i). APPLICATIONS OF DATA TRANSMISSION OVER POWER LINES.

The applications of PLDT are very wide and we can divide them into two categories: the

Medium Voltage or access technology mainly used by the utility authority and which is behind

the scope of the project and the Low Voltage or at home which cover the area of sending data

over power lines within the consumer‟s side and extends to all the electrical outlets within the

home.

(a) Low voltage or in-house.

Home automation.

Many years ago control of appliances in the home used to call for the establishment of new cable

wiring in the home. Power line data transmission technology can result in automation of

buildings. Hence we can control home appliances, light switches, wall outlets, thermostats, Heat

Ventilation and Air Conditioning systems, sensors, alarm and security.


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Street lights monitoring.

The use of PLDT to monitor street lights leads to big savings in the electricity bill of the

government by introducing selective dimming or selective turn-off features. This application can

increase energy savings by 30%

Low cost inter-device peer-to-peer networking.

Power lines may be used to create a network that links devices together on the power grid. Since

such a network makes use of the existing infrastructure, installation time and cost are virtually

non-existent. Since the outlet or junction box becomes a point where a device may be connected,

the device can be moved around numerous times.

(b) Medium Voltage and Low Voltage.

Utility.

a) Smart Meter Reading is a technology that uses the power line to send information to the

utility directly. Meters can be linked to concentrators to allow suppliers to have remote

access to each individual meter, to read or write information such as current, rates, pre-

paid amounts and cumulative counts, tampering detection, etc. Meters and/or

concentrators can also be used along with AC Remote LCD devices to replicate and

distribute their information to one or more points located anywhere on the electricity

network.

b) Load shedding: this is done when we need to reduce power given to load when we have

peak demands hours. As an example, incandescent light, with the help a of load control

circuit will receive less power when the utility notices that the demand for electricity is at

its peak in certain periods.


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2.3.4 ii) COMMUNICATION TECHNIQUES.

Communication is the process of accurately data transfer between two places. For

communication to take place there must be a receiver, a transmitter and a transmission medium.

Transmission medium can be air, wire or fiber cable.

Modulation is a process for moving a signal in a transmission medium via a high frequency

periodic signal. High frequency signal called carrier frequency. Data signal can change the

carrier frequency‟s amplitude, frequency or phase values.

These are the general ways for modulation. At the continuous wave operation, if the carrier is a

continuous periodic wave and the data signal is analog, this is called: Amplitude modulation

(AM), Frequency modulation (FM) and Phase modulation (PM). If the data signal is digital these

are: Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK) and Phase Shift Keying

(PSK).

Types of digital communication techniques:

Amplitude Shift Keying (ASK)

Mathematically the modulated carrier signal s (t) is

s (t) = f (t) cos(wct + Á) equation (i)

ASK is a special case of amplitude modulation (AM). Amplitude modulation has the property

of translating the spectrum of the modulation f(t) to the carrier frequency. The bandwidth of the

signal remains unchanged.

This can be seen if we examine a simple case when f (t) = cos(wt) equation (ii)

and we use the identities:

cos(A + B) = cos(A) cos(B) - sin(A) sin(B) equation (ii)

cos(A - B) = cos(A) cos(B) + sin(A) sin(B) equation(iv)


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then

s(t) = cos(wt) cos(wct) = 1=2[cos((w+ wc)t) + cos((w-wc)t) equation(v)

ASK is so sensitive for noise and propagation conditions. ASK is inexpensive and simple

modulation type than other modulation types. This modulation is shown in figure 2.2 (b).

Frequency Shift Keying (FSK).

An FSK describes the modulation of a carrier (or two carriers) by using a different frequency for

a 1 or 0. The resultant modulated signal may be regarded as the sum of two amplitude modulated

Signals of different carrier frequency

s(t) = f0(t) cos(w0t + Á) + f1(t) cos(w1t + Á) equation(vi)

FSK is classified as a wide-band if the separation between the two carrier frequencies is larger

than the bandwidth of the spectrums of f0 and f1.

FSK has many application areas in our daily-life (e.g. radio, modem, fax). FSK is very immune

to noise. Because noise can change the signals amplitude but it can‟t change the signals

frequency easily. This modulation is shown in figure 2.2 (c).

Phase Shift Keying (PSK).

At Phase Shift Keying, the data bits change the carrier signal‟s phase. Generally PSK uses two

different angles for communication. For instance, if the data signal‟s bit digital “0” output

sinusoidal wave‟s phase angle 0º and for digital “1” phase angle 180º. So two different angles

can transmit 1 bit and four or more angles can transmit 2 or more bit at 1-cycle. Quadrature

Phase-Shift Keying (QPSK) uses four phases and QPSK is the most known PSK type.

Bluetooth, wireless modems, satellite TV receivers and RFID cards use advanced PSK types.

This modulation is shown in Figure 2.2 (d).


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Figure 2.2: Digital Communication Techniques and their Expressions.

2.3.4 iii) CLASSIFICATION OF POWER LINE DATA TRANSMISSION.

Ultra-Narrowband.

These systems work in either Ultra Low Frequency (0.3–3 kHz) or in the Super Low Frequency

(30–300 Hz). “Ripple control” systems can be considered a historical example of this group of

PLDT technologies, even if these ripple control systems were one-way communications. They

convey very low data rates (roughly 100 bps) at tens or even one hundred kilometers.


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Narrowband.

These systems use the frequency band from 3 kHz to 500 kHz that include the European

Committee for Electro technical Standardization (CENELEC) A band (Europe, 3–148.5 kHz),

the Federal Communications Commission (FCC) band (USA, 10–490 kHz), ARIB band (Japan,

10–450 kHz) and Chinese band (3–500 kHz). These technologies have a range that depending on

the power lines can reach from hundreds of meters to some kilometers.

Narrow band PLDT technologies can be further classified as:

Low Data Rate (LDR) NB PLDT.

Single carrier technologies capable transmitting a few kbps;

High Data Rate (HDR) NB PLDT.

Multicarrier technologies capable transmitting hundreds of kbps.

2.3.4 iv) DIRECTIONS OF DATA TRANSMISSION.

Data transmission can be in both directions at the same time that is called full-duplex as shown

in Figure 2.3 (b). It can be in one direction but not at the same time that is called half-duplex

shown in Figure 2.3 (c). If the data transfer in one-way that is called simplex Figure 2.3

Figure 2.3: Directions of Data Transmission.


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2.3.4 v) CHALLENGES IN THE POWER LINE NETWORK.

Power lines are a hostile environment that makes the accurate propagation of communication

signals difficult and are not designed for data transmission use. Noise levels are excessive and

cable attenuation at the frequencies of interest is often very large. Important channel parameters

such as impedance and attenuation are time varying in unpredictable ways. Challenges

encountered in the power line data transmission are:

a) Disturbances.

Generally disturbances can be classified into two categories:

Superimposed disturbances

Includes:

Persistent oscillations, either coherent or random.

Transient disturbances, both impulse and damped oscillations.

On the medium voltage network, the superimposed disturbances are attributed to large factories

with extensive plant or machinery, and industrial users with poorly filtered appliances. On the

low voltage network, a number of household appliances are most often responsible for

superimposed disturbances.

Wave shape disturbances

Includes:

Under and over voltages, both persistent (>2 seconds) or surges (<2 seconds)

which are of little effect on the network due to the robustness of the transceivers.

Outages where there will be no transmission of information naturally.

Frequency variations can cause major problems as many simple systems rely on the

mains carrier (60Hz sine wave) for synchronization between transmitter and receiver.

Frequency variation in this wave will cause transmission error. Modern systems

overcome this obstacle by avoiding reliance on the mains carrier for synchronization.

Harmonic distortions are a major source of disturbance, yet these occur at frequencies

below those designated in the standards regulating PLDT.


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b) Noise.

Noise on electrical power networks on the Medium Voltage side is usually caused by corona

discharge, lightning, power factor correction banks and circuit breaker operation. In this project

am dealing with a low voltage network, and hence much of this noise is filtered by medium/low

voltage transformers.

Generally noises can be classified into into four categories:

Noise having line components synchronous with the power system frequency;

Noise with a smooth spectrum;

Single event impulse noise, and;

Non synchronous noise.

Noise having line components synchronous with power system frequency.

The usual source of this called type A noise are triacs or silicon controlled rectifiers (SCR‟s), found

within the transmission medium. The spectrum of this noise consists of a series of harmonics of the

mains frequency (60Hz).

Ways to reduce this kind of noise:

• As the frequency spectrum of class A noise is regular, successful communication may be possible

with modulation schemes that avoid, or have nulls, at these frequencies.

• Filter these noise components out using accurate notch filtering.

• Considering the time domain representation of class A noise, a noise pulse can be

expected at equal intervals. Using fairly simple time division multiplexing schemes and error

correction, unwanted effects can be minimized.

Noise with a smooth spectrum.

This can be referred to as type B noise with a smooth spectrum is generally caused by universal

motors. A result of the commutation process in motor powered appliances such as blenders and

vacuum cleaners, this noise has a flat spectrum in the frequency ranges used by PLDT systems. Thus

it can be modeled as band limited white noise.

A characteristic of many of the appliances that contain universal motors is that they are often used for

a short period of time. Thus, we can avoid this noise by operating the PLDT system when the noise is

absent. Conversely, real time systems must be able to cope with type B noise.


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Single event impulse noise.

Single event impulse noise (type C noise) is primarily due to switching phenomena-lightning, the

closing of contacts, etc. Type C noise disturbs the whole frequency band for a short amount of time

modeled as an impulse disturbance due to the relatively short time involved. Experience with impulse

noise in other communications environments shows that type C noise can be overcome by error

correcting codes.

Non synchronous noise.

Non synchronous noise (type D noise) is characterized by periodic components that occur at

frequencies other than harmonics of the mains frequency. Major sources of type D noise include

television and computer monitors. The scanning and synchronization signals in such appliances cause

noise components at known frequencies- for example, interference from a PAL system television set

is at 15734kHz and associated harmonics. Different standards of television and computer scanning

have different radiated noise components. The solution to minimizing such interference is to avoid

data transmission at 15734 kHz and associated harmonics, and to use of a modulation scheme that is

frequency diverse, thus avoiding potential type D noise at any unforeseen frequencies.

2.4. IMPEDANCE AND TRANSFER FUNCTION.

The characteristic impedance of an unloaded power cable can be obtained by a standard

distributed parameter model, and given by

equation(vii)

At the frequencies of interest for PLDT, this approximates to

equation(viii)


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Where:

L –is the line impedance per length and C –is the capacitance per length.

In summary the overall impedance of a low voltage network results from:

• Impedances of the devices connected to the network.

• Characteristic impedance of the cable used.

• Impedance of the distribution transformer.

Maximum power transfer theory states that the transmitter and channel impedance must be

matched for maximum power transfer. The system designer must design a transmitter and

receiver with sufficiently low output/input impedance (respectively) to approximately match

channel impedance in the majority of expected situations.

The signal attenuation for low voltage networks is around 100 dB/Km which leads to a need for

repeaters to be plugged in at desirables weak areas.

The main factors leading to signal attenuation are:

Time dependence.

Frequency dependence.

Distance dependence.

Difference between phases.

2.5. PROBLEM DEFINITION. There is an opportunity to enhance the capabilities of the existing power line infrastructure using

power line data transmission technology.

This opportunity would lead to several advantages as listed below:

Reduce the probability of costly and inconvenient power outages

Offer services such as broadband access.

Increase meter reading and efficiency, resulting into correct billing and supply of correct

energy required.

Efficient energy and network management


17

In this project, I would build a system to send and receive data through the power lines, which

will be similar to the Smart Meter Reader System. The analogues signal of sinusoidal waveform

is obtained from a signal generator at 132 KHz at a baud rate of 2400Kbps (Data Source) and

then sent to the power line, it should then be received from the power line and get displayed at

the oscilloscope.

2.5.1 Requirements.

Requirements for this product were identified as listed below:

Safely interface with power line

Low bit error rate

Low susceptibility to interference

Frequency Shift Keying as modulation scheme

Data source Data sink

Isolate the power signal from the data signal

High speed data transfer rate of 2400 kbps

These requirements form the basis for the solution that we developed to address the problem of

sending and receiving data over power lines.

2.5.2 Solution of the problem.

Smart Meter Reader consists of two basic units that are needed to facilitate the communication

between the smart meter and the smart metering aggregator. The smart meter unit would be

located at the client‟s building and the aggregator unit would be used by the energy provider‟s.

The main focus of the design was on the Transmitter power isolation circuit and Receiver

power isolation circuit using the HCPL-800J that would allow us to send and receive data

through the power line interface.


18

Figure 2.4: Smart Meter Reader System Block Diagram.


19

CHAPTER THREE.

3.1. INTRODUCTION.

The Transmitter power isolation circuit and Receiver power isolation circuit is designed in

this chapter. The design is based on an application of an Integrated Circuit called HCPL-800J.

HCPL-800J is a galvanically isolated Power line Data Access Arrangement IC.

It operates at a narrow band frequency of 125 KHz to 135 KHz and a High Data Rate of

2400Kbps.

Figure 3.1: HCPL-800J CHIP.

It provides the key features of isolation, Tx line driver and Rx amplifier as required in a power

line modem application, it is used together with a simple LC coupling circuit which performs the

isolation purposes.

HCPL-800J IC offers a highly integrated, cost effective Analogue Front End solution. Optical

coupling method offers a very high isolation mode rejection, resulting into an excellent EMI and

EMC performance.

Transmitter performance is achieved by the use of a high efficiency, low distortion Line Diver

Stage. The robustness of the Transmitter is further enhanced with integrated load detection and

over-temperature protection functions.

HCPL-800J IC is designed to work with various transceiver ICs and significantly simplify the

implementation of a Power Line Data Transfer.


20

3.2. CIRCUIT DESIGN.

The Power Line Data Transfer communication system developed contains two major Circuits

that are the Transmitter circuit and the Receiver circuit. The transmitter is responsible for

sending the signal to the power line. It includes the following stages: the signal modulation stage,

the signal amplification stage, and the power line isolation stage. The receiver is responsible for

receiving the modulated signal from the power line and recovering it to the original message

signal. It includes the following stages: the isolation with the power line, the signal amplification

stage, and the signal demodulation stage.

The block diagram of the system is shown below.

Figure 3.2: Circuit Block Diagram.

Power line Channel

240V /50Hz

Data Source DAC and Modulation/

Trans-receiver

Transmitter Power Isolation circuit

using HCL-800J IC

Data Sink/Output ADC and De-Modulation/

Trans-receiver

Receiver Power Isolation Circuit

using HCL-800J IC


21

3.2.1 HCPL-800J.

The HCPL-800J is designed to work with various transceivers and can be used with a variety of

modulation methods including ASK, FSK and BPSK.

For this project Frequency Shift Keying (FSK) modulation scheme was used with a frequency of

132 KHz and baud rate of 2400Kbps.

Figure 3.3: Internal Block Diagram of the HCPL-800J IC.

Tx LED Driver

TxTIA

GT2

Tx-en Detection

Line Driver Control

VCC2 UVD

Load

Detection

Over-Temp Detection

Rx LED

Driver

Rx

TIA

Status Detection

GR2

Control IC

Line IC

Rx-Amp-in

Rx-out

Tx-in

VCC1

Tx-en

GND1

Rx-PD-out

Status

Tx-PD-out Tx-LD-in

Tx-out

Rx-in

Rref

VCC2

GND2

Cext

1

2

7

8

5

6

4 3

10

9

11

16

14

15

1213

Status Logic

AGC

Shield

Shield

Amp

Tx LED Driver

TxTIA

GT2

Tx-en Detection

Line Driver Control

VCC2 UVD

Load

Detection

Over-Temp Detection

Rx LED

Driver

Rx

TIA

Status Detection

GR2

Control IC

Line IC

Rx-Amp-in

Rx-out

Tx-in

VCC1

Tx-en

GND1

Rx-PD-out

Status

Tx-PD-out Tx-LD-in

Tx-out

Rx-in

Rref

VCC2

GND2

Cext

1

2

7

8

5

6

4 3

10

9

11

16

14

15

1213

Status Logic

AGC

Shield

Shield

Amp


22

Figure 3.4: HCPL-800J Package Pin Out.

Table 3.1. Pin Descriptions.

Pin No. Symbol Description

1 Tx-en Transmit Enable Input

2 Tx-in Transmit Input Signal

3 Rx-PD-out Rx Photo detector Output

4 Rx-Amp-in Receiver Output Amplifier Input

5 Status Signal indicating Line Condition

6 Rx-out Receiving Signal Output

7 VCC1 5 V Dc Power Supply

8 GND1 VCC1 Power Supply Ground

9 Rref Sets Line Driver biasing current, typically 22 kΩ

10 Rx-in Receiving Signal Input from Power line

11 Cext External Capacitor

12 Tx-LD-in Tx Line Driver Input

13 Tx-PD-out Tx Photo detector Output

14 VCC2 5 V Power Supply

15 Tx-out Transmit Signal Output to Power line

1

Tx-in

Tx-en

VCC1

Status

Rx-out

Rx-in

Rx-PD-out

Rx-Amp-in

GND1

GND2

Cext

Tx-out

Rref

Tx-PD-out

Tx-LD-in

VCC2

2

3

4

5

6

7

8

16

9

15

14

13

12

11

10


23

16 GND2 VCC2 Power Supply Ground

3.2.2 TRANSMITTER POWER ISOLATION CIRCUIT.

The analogue Tx input pin is connected to the modulator via an external coupling capacitor and a

series resistor. The Optimal performance is obtained with an input signal of 250 μApp.

To ensure a stable and constant output signal at Tx-PD-out, HCPL-800J includes an Automatic

Gain Control (AGC) circuit in the isolated transmit signal path.

AGC circuit compensates for variations in the input signal level presented at Tx-in and variations

in the optical channel over temperature and time.

The optical signal coupling technology used in the HCPL-800J transmit path achieves very good

harmonic distortion typically HD2 < -50 dB and HD3 < -62 dB, which is usually significantly

better than the distortion performance of the modulated input signal. However to meet the

requirements of some international EMC regulations it is often necessary to filter the modulated

input signal. The optimal position for such a filter is between pins 13 and 12 shown in figure 3.5.

Transmitter Line Driver.

The line driver is capable of driving power line load impedances with output signals up to 5 V

peak to peak. The internal biasing of the line driver is controlled externally via a resistor Rref

connected from pin 9 to GND2. The optimum biasing point value for modulation frequencies up

to 150 kHz is 22 kΩ.

The output of the line driver is coupled onto the power line using LC- coupling circuit shown in

figure 3.8. Capacitor C6 and inductor L1 attenuate the 50/60 Hz power line transmission

frequency. A suitable value for L1 was taken to be 330uH. To reduce the series coupling

impedance at the modulation frequency, L2 is included to compensate the reactive impedance of

C7. This inductor should be a low resistive type capable of meeting the peak current

requirements.Using a high Q coupling circuit results into a wide tolerance on the overall

coupling impedance, causing potential communication difficulties with low power line

impedances.

Although the series coupling impedance is minimized to reduce insertion loss, it has to be

sufficiently large to limit the peak current to the desired level in the worst expected power line

load condition.


24

Figure 3.5: Transmitter Power Isolation Circuit Schematic Circuit.

Figure 3.6: Band Pass Filter Circuit.

L1

Input Output

C12.2nF820uH

R1

O.5K

GN

D2

Filter100 µF

VCC2

GN

D2

R ref

22 k

C1

100 nF

GN

D2

R2

2

100 nF

VCC1

100 nF

1 µF

GND1

Tx-en

Tx-in

R1

2 k

HCPL-800J

1

2

3

4

5

6

7

8 9

10

11

12

13

14

15

16Tx-en

Tx-in

Rx -PD-out

Rx -Amp-in

Status

Rx -out

VCC1

GND1 Rref

Rx-in

Cext

Tx-LD-in

Tx-PD-out

VCC2

Tx-out

GND2

5V

Signal in

High 5V

Dc Power supply

Ground/Earthing

5V

Power supply

Ground/Earthing

Signal out to LC coupling

C2

C5C3 C4


25

3.2.3 RECEIVER POWER ISOLATION CIRCUIT.

The received signal from the power line is often heavily attenuated and also includes high levels

out of noise band. Receiver performance was improved by positioning a suitable baseband filter

prior to the Rx-in input as shown in figure 3.6.

To counter the inevitable attenuation on the power line, the HCPL-800J receiver circuit includes

a fixed 20 dB front-end gain stage. This configuration results in the best SNR and IMRR.

The optically isolated Rx signal appears at Rx-PD-out. This signal is subsequently AC coupled

to the final gain stage via a capacitor.

The final gain stage consists of an op-amp configured in an inverting configuration and DC

biased at 2.27 V. The actual gain of this gain stage is user programmable with external resistors

R5 and R1 as shown in figure 3.7. The signal output at Rx-out is buffered and may be directly

connected to the demodulator or ADC, using AC coupling if required.

Figure 3.7: Receiver Power Isolation Circuit Schematic Circuit.

Status

Rx-out

Rref

22 k

GN

D2

100 nF

VCC1

GND1

HCPL-800J

8 9GND1 Rref

Ground/Earthing

Ground/

Earthing

Signal in from

C2 LC coupling

10kR6

Filter

100 µF

VCC2

GN

D2

C14

100 nF

100 nF

1 µF

R5

5k

1

2

3

4

5

6

7 10

11

12

13

14

15

16Tx-en

Tx-in

Rx-PD-out

Rx-Amp-in

Status

Rx-out

VCC1 Rx -in

Cext

Tx-LD-in

Tx-PD-out

VCC2

Tx-out

GND2

5V

Dc Power supply

5V

Power supply

C5C3 C4


26

3.2.4 Power Line Isolation Circuit.

The design of an optimum isolation coupling circuit, the appropriate components was chosen as

below:

Coupling capacitors:

Used to couple the signal to the power line, also as a part of more sophisticated higher-order

filters .Coupling capacitors carry the communication current and hence they have to be high-

frequency capacitors. Conversely, they have to filter the power voltage, as well as voltage surges

and therefore need to be high-voltage capacitors. The filtering characteristics of the coupling

capacitors are quite dependent on the load onto which the waveform terminates.

Blocking inductors:

They are designed for the power frequency to aid in the prevention of saturation and for the

power current to prevent voltage-drops. The inductors block the modulation frequency, and

therefore self-resonant point needs to be above that frequency.

Resistors:

They implies a loss of power, either of the communication signal or the power waveform

Zener Diode

Allows current to flow in the forward direction in the same manner as an ideal diode, but also

permits the the flow in the reverse direction when the voltage is above the breakdown voltage.

Also protect other semiconductor devices from momentary voltage pulses.


27

Figure 3.8: LC Coupling Circuit.

3.2.5 Power Supply.

The recommended voltage regulator to supply Vcc1 and Vcc2 is 78L05. To minimize harmonic

distortion, a tantalum decoupling capacitor of at least 10 μF together with a 100 nF ceramic

capacitor was connected in parallel. The capacitors should be positioned as close as possible to

the supply input pin.

Figure 3.9: Power Supply circuit.

C6

220nF

Neutral

1 µF

L2

Phase

L1330 µH

Zener Diode

6.8 µH

240V/50Hz

Pin 15

1AC7

GN

D2

signal in from HCPL-800Jto LC coupling

Pin 10

signal in from to

LC couplingHCPL-800J


28

3.3. PRINTED CIRCUIT BOARD LAYOUT.

Figure 3.10: PCB Layout.

i).Transmitter power isolation circuit


29

ii). Receiver power isolation circuit.


30

3.4. THE CIRCUIT BUILT.

Figure 3.11: Circuit Built.

i).The Transmitter.

Arial-View.

Side view.


31

ii).The Receiver.

Arial-View.

Side view.


32

CHAPTER FOUR.

RESULTS AND ANALYSIS.

The Transmitter power isolation circuit and Receiver power isolation circuit were designed

and built.

Figure 4.1: Transmitter power isolation circuit connection side.


33

Figure 4.2: Receiver power isolation circuit connection side.


34

The tests were done and results obtained from the simulated data and practical data.

4.1 SIMULATED RESULTS.

Figure 4.3: Input and Output result on Proteus.

It was observed that the sinusoidal signal supplied to the transmitter power isolation circuit was

coupled into the power line and received from the power line by the power line isolation circuit

and then displayed by the digital oscilloscope at the receiving end.

Figure 4.4: LC filter result on Proteus.


35

It was observed that the LC filter at the LC coupling circuit allowed frequency signal of 132

KHz and above to pass through while blocking the lower frequencies.

4.2 PRACTICAL RESULTS.

Figure 4.5: Input from the Signal Generator at 132 KHz.

From Figure 4.1 it can be seen that the input signal (analogue sinusoidal waveform at a

frequency of 132Kz) was supplied from a signal generator to the transmitter power line isolation

circuit. The input signal is also displayed on the oscilloscope as shown in figure 4.5, so that it

can be viewed and compared with the received output signal. The output of the transmitter power

line isolation circuit was connected to an LC coupling circuit. The LC coupling circuit is directly

plugged into the power line and its sole purpose is to prevent any inadvertent damage to the

power line of 240 V / 50 Hz (and any devices connected to it) by the circuit.


36

Figure 4.6: Output displayed on Oscilloscope, at 132 KHz.

The received message was received by the LC coupling circuit which, coupled the receiver

power line isolation circuit with the power line of 220 V / 50 Hz, the output of the receiver was

then connected to an oscilloscope as shown in figure 4.2.

From Figure 4.6, an output signal (analogue sinusoidal waveform at a frequency of 132 KHz)

was observed from the oscilloscope.


37

CHAPTER FIVE.

5.1. CONCLUSION.

The Power line data transfer is a valid technique that allows the transmission of data by means of

the power line cables that are present in every dwelling. Power line can be used to share data

with high bit rates up to 2400 Kbps

The implementation of the device, named Smart Meter Reader, began with the design of a

transmitter power isolation circuit and receiver power isolation circuit. The circuit would need to

be able to receive analogue modulated signal from a trans-receiver and then interface with the

power line. I successfully created such a circuit using Frequency Shifting Keying modulation

technique and HCPL-800J chip. The receiver was also built using Frequency Shifting Keying

modulation technique and HCPL-800J chip, the circuit would need to be able to receive the

signal from the power line to the trans-receiver. The LC filter was created to allow the signal be

passed both from the sending side to the power line and to the receiving side as shown in figure

4.4.

In conclusion, the project design objective which was Implementation of data transmission over

a power line to transfer data at a rate of 2400 Kbps from a smart meter to a smart metering data

aggregator was successfully achieved.

The system was able to couple the sinusoidal signal from the signal generator to the power line

of 240 V / 50 Hz and to retrieve the signal and then displayed on the oscilloscope as shown in

figure 4.5 and figure 4.6.


38

5.2. RECOMMENDATIONS.

PLDT can be used to transmit high speed data where there is a very critical communication with

a very narrow-band filter. The communication speed is increased by power saving lamps and line

filters. Automatic gain control should be added to the receiver input to work properly with the

short and long distance. If the received signal is processed by a DSP with FFT algorithms, better

results will be recorded. Speed can be increased by using multiple narrow bands such as: WI-Fi,

GSM modules, GPRS modems and RF transceivers may be preferred.


39

REFERENCES.

[1] Thomas and Rosa, The Analysis and Design of Linear Circuits, New York: John Wiley &

Sons, Inc., 2001.

[2] Amit Dhir et al, “Home networking using no new wires phone line and power line

interconnection technologies”, White Paper, WP133,Xilinx Inc.,March 2001.

[3] EN50065-1, “Signaling on low-voltage electrical installations in the frequency range 3 kHz

to 148.5kHz”, CENELEC; Genevre, July 1993.

[4] S. Robson, Student Member, IET, A. Haddad, Member, IET and H. Griffiths, Member, IET,

“Simulation of Power Line Communication using ATP-EMTP and MATLAB”.

[5] Cuncic, P. & Bazant, A. (2003). Analysis of Modulation Methods for Data Communications

over the LOW-voltage Grid, Proceedings of 7th International Conference on

Telecommunications, pp.643-648, ISBN 953-184-052-0, Croatia, June 2003, Zagreb.

[6] K. C. Abraham and S. Roy, “A Novel High-Speed PLC Communication Modem”, IEEE

transactions on Power Delivery, Vol. 7, No. 4, October 1992.

[7] Communication Systems Engineering (2nd Edition), John G. Proakis ,Masoud Salehi

,2002,ISBN 0-13-061793-8.

[8] A.R Bergen,V.Vital, "Power systems analysis”, Prentice Hall, second edition 2000.

[9] Sabolic, D. Influence of the transmission medium quality on the automatic meter reading

system capacity. IEEE Trans. Power Deliv. 2003, 18, 725–728.

[10] http://www.ieeeghn.org/wiki/index.php/Telephony_over_Power_Lines_(Early_ History).

[11] Design Notes, “Home Automation Circuits.” (Online article), Available at:

http://www.designnotes.com/CIRCUITS/FMintercom.htm.


40

APPENDICES.

Appendix 1: HCPL-800J IC Data sheet.

Appendix 2: Voltage regulator 78L05 Data sheet.

Appendix 3: Varistor Data sheet.

Appendix 4: Cost analysis

Appendix 3: Cost analysis

Table 5.1. Bill of Quantities.

COMPONENTS COST

HCPL-800J IC CHIP*2 1000

VOLTAGE REGULATOR*2 200

DIODE*2 60

PCB 1500

BRIDGE DIODES*8 80

ZENER DIODE*4 80

VARISTOR*2 160

JUMPERS 150

FUSE *2(1AMPS) 20

LED*2 10

RESISTORS*8 40

INDUCTOR*4 200

ELECTROLITIC CAPACITORS*18 720

CERAMIC CAPACITOR*2 160

TOTAL 4,220

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