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Chapter 1

ELECTRICITY THEFT

1.1 PROBLEM

An electric power system can never be 100% secure from theft. In many systems the

amount of theft is small (1–2%) in terms of the electricity generated. But, the financial loss

is high due to the large amount of electricity distributed. Nesbit (2000) noted that, ‘‘In the

US, the consensus seems to be that theft costs between 0.5% and 3.5% of annual gross

revenues in the US. That seems like a small amount—until you consider that US electricity

revenues were in the $280 billion range in 1998.Therefore, between $1 and $10 billion

worth of electricity was stolen.’’ Some power systems may forfeit more than 15% of power

generated to various types of theft. Transparency International (1999) report explains the

situation in Bangladesh. In fiscal 1998–99 Bangladesh Power Development Board (BPDB)

generated 14,150 MkWh of electricity, purchased another 450 MkWh from private sources,

but billed for only 11,462 MkWh, giving a system loss of 22%.This was better than Dacca

Electric Supply Authority (DESA) 40% but poorer than Rural Electrification Board (REB)

17%.The weighted average system loss in the power sector as a whole is estimated at 35%,

which includes 21% technical loss.

The balance 14% y was due to pilferage, theft and unauthorized use. The financial losses

are critical to many electric power organizations. Lost earnings can result in lack of profits,

shortage of funds for investment in power system capacity and improvement, and a

necessity to expand generating capacity to cope with the power losses. Some power systems

in worst affected countries are near bankrupt. Corruption increases and becomes entrenched

as favors can be ‘‘bought’’ from power sector employees in the form of inaccurate billing

and allowing illegal connections. Political leaders intervene to ensure that cronies and

supporters are not prosecuted.

In 1998, the situation deteriorated in Pakistan to the extent that, The government took action

and employed 35,000 army men to recover Water and Power Development Authority

(WAPDA) dues and curb the theft. They have been conducting house-to-house raids with

the staff of WAPDA, checking for any tampering of power meters. In the last year the army

has found 100,993 instances of power theft, recovered Rs.2.4 billion in fines and penalties

and arrested 1188 people. Embarrassingly, many of the thefts were discovered in the

houses, farms and mills of the ruling party legislators, 13 of whom were WAPDA officials

Even the Minister for Population y resigned from her cabinet post on power theft charges

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(Rizvi, 2000). Electricity theft is a complex phenomenon with many facets. In this article,

electricity theft is defined and various types of theft are described. The international scope

and trends of theft will be examined. How theft can become institutionalized as part of the

political, economic and managerial culture of governance will be noted. Lastly, some

methods of dealing with the problem of electricity theft are examined.

1.2 DEFINING ELECTRICITY THEFT

Four kinds of ‘‘theft’’ are prevalent in all power systems. The extent of the theft will depend

upon a variety of factors—from cultural to how the power utility is managed.

1.2.1 Fraud

Fraud is when the consumer deliberately tries to deceive the utility. A common practice is

to tamper with the meter so that a lower reading of power use is shown than is the case.

This can be a risky procedure for an amateur, and many cases of electrocution have been

reported. In Malaysia, ‘‘professionals’’ have approached residents and managers of

businesses offering to ‘‘fix’’ the meter for a moderate fee (New Straits Times, 1999).During

2 months of raids in Malaysia on suspected areas 587 (86%) out of 684 inspected were

confirmed to have tampered with their meters or stolen electricity (The Star, 1998).The

losses can be substantial when fraud is by large organizations. In Aurangabad, India, The

22 proprietors of Jalna’s seven mini-steel plants accused of massive power theft detected

in Monday’s raids by the Maharashtra State Electricity Board (MSEB) are absconding

following the rejection of their plea for anticipatory bail by the Sessions Court by The

MSEB has conclusive proof of the Rs 20 crore (Rs 200 million) power theft y (including)

extremely sophisticated equipment the steel plants used to doctor their electricity metersy

(Indian Express, 1998.

1.2.2 Stealing Electricity

Electricity theft can be arranged by rigging a line from the power source to where it is

needed bypassing a meter. In South Asian countries this practice is quite common in poor

residential areas where those wanting electricity may not have lines allocated and may not

be able to pay if they were connected called the ‘Kunda’ system in Pakistan, this practice

is often accepted by power managers as a fact of life in poor communities. In Soweto, South

Africa 6 tons of ‘‘spider web’’ cable used for such connections was recovered in 6 months

by the electrical authority in raids (Campbell, 1999).

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In Mexico, The millions of illegal customers, who steal electricity with wires known

as diablitos, or ‘little devils,’ have pushed an overburdened electrical grid over the edge.

By thousands of homes and businesses have been hit with power outages that electric

company officials blame largely on pirates. Published reports say the thefts result in the

loss of as much as $475 million revenues annually (Sullivan, 2002). The illegal lines are

easy to detect as they are often above ground and highly visible. However, one finds reports

of staff being assaulted and needing police security to carry out the removal of the lines.

Corrupt staff from the electricity organization may take bribes to allow the practice to

continue .On a larger scale, businesses may bribe power organization staff to rig direct lines

to their buildings or offices and the power does not go through a meter. The bribes can be

much less than the cost of the power. Money also can be given to inspectors to keep them

from finding and/or reporting the theft.

1.2.3 Billing Irregularities

Billing irregularities can occur from several sources. Some power organizations may not

be very effective in measuring the amount of electricity used and unintentionally can give

a higher or lower figure than the accurate one. The unintentional irregularities may even

out over time. However, it is also very easy in some systems to arrange for much lower

bills to be given than for the power actually used. Employees may be bribed to record the

meter at a lower number than is shown. The consumer pays the lower bill and the meter-

reader earns unofficial salary.

In another type of billing irregularity, office staff can move the decimal point to the left on

the bill so that a person or company pays $47.48 instead of $474.80. Consumers may know

that some power organization staff are ‘‘on-the-take’’ for providing these services.

Employees may keep payments. A scheme in operation in Malaysia in the late 1990s

diverted $1.59 million to private accounts before detection (BRDC, 2000).The staff can

easily earn from this type of corruption, as it is not easy to detect. Corrupt practices may

become institutionalized to the extent that employees regard the illicit payments as part of

the job.

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1.2.4 Unpaid Bills

Some persons and organizations do not pay what they owe for electricity. Residential or

business consumers may have left the city or an enterprise has gone bankrupt. In South

Africa a ‘‘culture of non-payment’’ is evident (Mkhwanazi, 1999).

In Armenia, ‘‘Nonpayment levels of 80–90% are typical in the residential sector. T&D

losses are over 40%’’ (Tacis, 1998).The practice is widespread, some systems have chronic

non-payers—the very rich and politically powerful who know that their electricity will not

be cut regardless of whether they pay or not.

In India, farmers in some states regard electricity as a free service from government, and

some political leaders and parties curry favor by promoting this practice and prevent the

State Electricity Boards from collecting. Another chronic non-payment group can be

government departments and agencies. The Pakistan Army discovered that some of the

largest amounts owed to WAPDA were from government agencies—including the Army

itself. The Karachi Electric Supply Corporation Director reported in 2000 that only 52

percent of the 1.67 million customers were paying their bills (News International, 2000).

In Indonesia in 2000, the military owed Rp.23 billion (US$3.1 million) to Perusahaan

Listrik Negara (PLN). This was a large part of the company’s total unpaid claims of about

Rp.157 billion (Jakarta Post, 21 March 2000).Some analysts may not regard non-payment

by as ‘‘theft.’’ However, when it becomes institutionalized and people and organizations

expect that they can get away with it, unpaid bills should fall into the ‘‘theft’’ category.

Non-payment is a problem not confined to poor countries.

Lundin (2001) has explained the growing problem in the USA. In all countries, as

electricity increases in price, some people have trouble paying their ARTICLE IN PRESS

T.B. Smith / Energy Policy 32 (2004) 2067–2076 2069 bills regularly. This may encourage

them to find ways of reducing their bills, such as tampering with the meter. In a more

conventional definition of electricity theft the category of Unpaid Bills may not appear.

However, in some power systems the extent of the problem and its impact has serious

consequences. Data on non-payment is not available easily that can be used for a

comparative analysis for the purposes of this paper. The analysis in this paper deals

primarily with theft in terms of billing irregularities, fraud and stolen electricity

1.2.5 Measuring Electricity Theft

Electricity theft can be estimated, but not measured exactly. The most accurate estimate of

theft is by conducting a thorough analysis of the power system.

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The revenue protection section of the Arizona Public Service Company (APS) carried out

a recent study that is unique (Culwell,2001).The APS provides electric power to the

Phoenix metropolitan region and 11 of Arizona’s counties—covering 40,000 miles2 with

868,000 customers.

The APS wanted a research project that would go beyond the usual studies that target meter

tampering. They wanted to know the extent of meter tampering and the financial loss in

such a way as to be able to extend the research to the whole of the APS system with a 95%

confidence. The study involved selecting randomly 550 meters out of the 868,000, ensuring

that they were spread among the urban and rural users (35% rural) and residential and

industrial (12%) users. Each meter was thoroughly inspected– disconnected, opened,

tested, and 52 items of information recorded about the meter. For determining theft the

‘‘beyond a reasonable doubt’’ criterion was used. Suspected theft required evidence that

was ‘‘clear and convincing.’’ The research study was implemented beginning on 3 April

2000 and was completed by 30 June the same year.

The findings include:

• Definite meter tampering rate—0.72%.

• Probable meter tampering rate—1.00%.

• Actual loss in dollars—$330,148.

The data was extrapolated to the APS system to estimate that nearly 15,000 meters had

been tampered with and show that the tampering losses per year were estimated to be

$7,967,279 that was 0.518% of revenue loss for the APS. The APS study noted that the

estimated loss ($5.1 million) was much higher among commercial accounts than the

residential consumers. The standard method of measuring power theft is by analysis of

transmission and distribution losses (T&D losses).

The method takes the difference between the amount of electricity generated (minus system

use and gratis) in relationship to the amount metered and sold. If an accurate calculation is

made of technical line losses, theft may compose a large part of the unaccounted amount—

the non-technical line losses in the distribution network. Very efficient power systems have

less than 6% T&D losses—theft may be 1–2%.Less efficient systems may have 9–12%

T&D loss and inefficient systems have line losses of over 15%.

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The Malaysian Tenaga system has T&D losses of 11% that includes theft losses estimated

at 4%.Bangladesh estimates are T&D losses of 35% with 14% as theft. In Budapest, Elmu

estimates that half of its 13% losses are due to theft (East European Energy Report,

1999).Indonesia’s PLN estimated theft in power distribution in Jakarta at 7% in 1994 and

3.77% in 1996 (Priatna, 1999).Thus, a system operating with 22% T&D losses could lead

analysts to estimate that around 10–15% are due technical T&D losses. The remaining 7–

12% of the electricity disappeared, probably due to theft of various types. This is a blunt

method for estimating theft and does not include non-payment.

1.3 POWER THEFT

A comparative and historical perspective Information is available on T&D losses for many

countries from the World Bank. However, World Bank data on T&D losses for some

countries is inaccurate and misleading as ‘‘0’’ T&D losses are recorded, or the figure given

is less than 1%.This is impossible because some electricity always is lost during

transmission and distribution. It is neither realistic nor feasible to assess T&D losses in all

countries given the limitations in the data. For this study, a sample of 102 countries was

chosen. The basic data for the countries is from the World Bank’s Development Indicators

(2003).

The main criteria for selection are:

Available data on T&D losses for 1980 and 2000 to enable an historical perspective.

Reasonable confidence in the accuracy of the data and that system use was not

included.

Countries selected have a good record in the collection of data in other social,

economic and power sector variables.

The confirmation of the country data by a second source such as the US EIA, reports

on energy development, and statistics bureaus and electricity organizations in the

selected countries.

The lowest T&D losses (less than 6%) are in countries known for efficiency in

management such as Finland, Germany, Japan, Republic of Korea, Netherlands, Singapore,

Belgium, Austria, France and Switzerland. The power organizations are managed to ensure

the deterrence, detection and prosecution of people and organizations engaged in electricity

theft. While there is a low percentage of theft, the economic losses can be high due to the

large amount of electricity generated. High losses (over 30%) are in countries such as

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Albania, Haiti, Myanmar, Kyrgyz Republic, Nigeria, and Bangladesh. Common features

are poverty and that each country has experienced political, economic and social turmoil.

In tumultuous times government organizations cease to function efficiently, become prone

to corrupt practices, investment is not made in system management, and the consumers take

advantage of the system Variations in T&D losses within each country may be large. In the

Philippines the T&D losses were estimated to be 17% in 1997.However, assessment of

regional variations shows that six of 15 regions had losses below 17%.One region has over

27% loss and five were between 20% and 27%.The Meralco region (Manila) reported

losses of 12.4%, well below the rural areas (National Economic Development Authority,

1998, Table 5.4). India has overall T&D losses of over 26%, but the losses vary in the 22

states. Losses of nearly 50% are experienced in Delhi, Jammu and Kashmir, and Orissa.

Even Maharashtra, with the best record, has nearly 15% losses.

1.4 GOVERNENCE AND ELECTRICITY THEFT

Understanding governance has emerged as an important element in explaining patterns of

social, economic and political development Kaufmann et al., 1999).Electricity theft is

related to a broader culture of governance or mal-governance. The World Bank Institute’s

Governance, Regulation and Finance Unit have compiled useful data. Attempting to

measure governance, Kaufmann and associates developed six measures to assess the

various dimensions of governance. Multiple indicators were used to measure each

dimension for 175 countries. The dimensions are:

Voice and accountability:

Aspects of the political process, civil liberties and political rights. Political instability and

violence: The likelihood that the government may be overthrown by violent means.

Government effectiveness:

The quality of public service provision and the bureaucracy, competence of civil servants

and the independence of the civil service from political pressure. Regulatory burden:

Incidence of market un-friendly policies such as price controls, and perceptions of burdens

imposed by excessive regulation.

Rule of law:

Abiding by the rules of society, effectiveness of the judiciary, and enforceability of

contacts.

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Graft and corruption:

The exercise of public power for personal gain, bribery, impact of corruption on business.

In the Indian, Pakistan and Bangladesh cases, the overwhelming evidence is that corrupt

practices are widespread in the electricity sector. The Lucknow Electrical Services

Authority General Manager conceded that, ‘‘Out of 110 million unit of electricity supplied

to the residents of Lucknow, at least 33% are pilfered and resulting in losses worth Rs 100

crores (Rs 1 billion) every year. He also admitted that most of the pilferage took place in

connivance with power employees’’ (Tripathi, 2000).

1.5 THE CONSEQUENCES OF ELECTRICITY THEFT

From a business perspective, electricity theft results in economic losses to the utility. Some

may argue that large utilities providing essential services give poor service, over-charge,

make too much money anyway, and, therefore, some theft will not break the company or

drastically affect its operations and profitability. Others looking at the same situation would

argue that theft is a crime and should not be allowed.

An International Utilities Revenue Protection Association has been established to

promote the detection and prevention of power theft–mainly for the financial security of

power utility companies. The consequences of theft in the worst case systems are important

to the viability of the services provided.

The combined losses (including non-payment of bills) in some systems have severe impacts

resulting in utilities operating at a loss and must continually increase electricity charges.

Locked into a culture of inefficiency and corruption, the electricity utilities have difficulty

delivering reliable service. Even in reasonably efficient power systems, such as Malaysia’s

Tenaga, power theft accounts for losses of RM$500 million ($132 million) annually (Malay

Mail, 1999).For large systems a 1% theft loss can be substantial.

With sales of over $13 billion, 1% of theft for the Korea Electric Power Corporation is over

$130 million. Lovei and McKechnie (2000) make a case that power theft impacts upon the

poor by perpetuating a system that benefits the wealthy and powerful. Power systems may

also promote ‘‘Grand Theft’’ by awarding lucrative contracts and monopolies that lead the

enrichment of favored individuals. India’s power system is an illustration of a worst-case

situation. In constant turmoil, State Electricity Boards (SEBs) have a high theft level and

consumers do not pay their bills.

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The SEBs seldom have profits and are heavily subsidized for their losses (Smith,

1993).Only three SEBs made a profit in 1996/97 and the combined commercial losses were

over 71 billion Rupees (about $1.6 billion). The SEBs cannot pay their bills for power

purchased from the central government or IPPs nor for plant equipment and the railways

for coal delivery. The whole system has been on the verge of financial collapse ARTICLE

IN PRESS Table 3 Governance indicators and T&D losses Governance dimension

Correlation T&D losses Level of significance Voice and accountability. IPPs, especially

foreign owned ones, are reluctant to enter the power field for fear that SEBs will not be

able to pay them for power supplied.

1.6 WHAT CAN BE DONE?

Electricity theft can never totally be eradicated in any power system. In the very efficient

systems of Japan, Western Europe and North America effort has been devoted to the

technological and managerial methods necessary to reduce theft to levels tolerable. Many

of these systems operate in a governance culture that promotes organizational efficiency

and theft law enforcement. This does not mean that electricity consumers necessarily love

their power company, but few will try to steal electricity.

Power system strategies for dealing with theft vary. Some organizations pay little attention

to theft problems, perhaps hoping theft will disappear and not become a public issue. Other

power systems treat electricity theft as highest priority. The first-step in electricity theft

reduction is to become knowledgeable about the theft problem. Few detailed studies of

power theft exist and the work of the Prayas Energy Group (2002) in India provides many

insights. Unless the nature and extent of power theft is known in great detail, any attempts

to deal effectively with the problem are prone to fragmented and limited action that have

little over-all success. Therefore, power systems, whether national or regional, should be

encouraged to initiate a detailed power theft analysis.

The analysis must go beyond conventional engineering and managerial frameworks and

understand and explain why theft occurs and what factors perpetuate theft.The information

derived is essential to design an appropriate strategy for dealing with theft

1.7REDUCING POWER THEFT

Three methods of reducing power theft are identified here:

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1.7.1 Technical/engineering Methods

Electric power is not a new technology and innovations taking place enable very efficient

systems to be installed and maintained. Many power systems devote inadequate resources

and effort to transmission and distribution systems and do not use the latest technologies.

The investment necessary to reduce losses includes upgrading power lines,

transformers, information technology monitoring systems, and installing and maintenance

of modern metering systems that are at the interface of the organization and the consumers

of the electricity. Significant technological advancement in metering has occurred.

Since much theft is from meter tampering, it is important to replace old, easy to tamper-

with meters. New high-tech sealed meters that cannot be altered in any way and can be read

automatically are costly, but can reduce theft when required of moderate to heavy power

users (see Arruda, 2000; Iyer, 2000; Rajan, 1998). Szilvagyi (1999) makes a strong case

that the investment in high technology metering requires a sound and complex

infrastructure in place to make the system work effectively.

1.7.2 Managerial Method

Electric power organizations are very large entities that operate as bureaucracies even

though many are private sector organizations. Combining strong technical improvements

with an intelligent and active anti-theft program may result significant improvements (see

Ahmedabad Electricity Co.Ltd., 2000). Inspection and monitoring power users at regular

intervals is essential to reducing theft (Gower, 2000).In Brazil, CEMIG had losses of $12

million.By spending $2.1 million on tests and inspection, $6.2 million was recovered

(Arruda, 2000).

The focus should be on areas or facilities that have the greatest potential amount of

electricity theft in terms of electricity use.Studies have shown that the wealthy steal power

for residential use, factories, and businesses (BRDC, 2000).More people may be stealing

power in urban slum areas, but the amount of power is small by comparison.

Yet inspection often targets the poor of the community. Singapore’s former Prime Minister

Lee Kuan Yew commented that corruption was a ‘‘fact of life’’ and in Singapore it should

not become a ‘‘way of life.’’ The same comment could apply to electricity theft. Theft may

be prevalent in all power systems to varying degrees as a ‘‘fact of life’’. Clearly, some

power systems appear to be operating where electricity theft has become a ‘‘way of life’’.

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Corruption is one of the most difficult problem areas for electricity organizations because

power theft occurs with the connivance of employees of the power organization. Increased

investigation and surveillance may provide opportunity for more corruption (Anuradha,

2000).Employees may even extort money from electricity consumers not to disclose theft.

It is important to detect and prosecute corrupt power sector employees—this includes, if

necessary, the ones at the very top of the organization. Employees should be paid

adequately so that they will not have to resort to bribes in order to support a family.

ARTICLE IN PRESS T.B. Smith / Energy Policy 32 (2004) 2067–2076 2073

The organizational factor in the power industry is important. Power utilities are very large,

complex organizations. By the number of employees it can be a country’s largest

organization. EGAT and the two distribution agencies in Thailand have over 60,000

employees, Indonesia’s PLN has over 50,000.Tenaga in Malaysia has 23,000 and WAPDA

in Pakistan has over 100,000.Nearly one million work in India’s state electricity boards.

Most of the tasks are routine and in many organizations a bureaucratic culture is promoted

whether private or public enterprise. Electricity utility employees must interface

extensively with the consumers of electricity—in residences, factories and offices

This allows ‘‘street level’’ decision making to take place (Lipsky, 1980; Hudson, 1993).

Employees can exercise discretion by not reporting infringements or may alter bills.Since

the typical power sector organization must operate at the consumer level, employees are

scattered throughout the far corners of the country, making control and coordination from

the central office difficult.

When the product delivered is a scarce and essential commodity, as is electric power

in South Asian countries, employees can exercise considerable discretion. Routine

allocation found in some power systems becomes discretionary in others. For example, who

will get connected to power? When will the connection be made? Where and when will

power blackouts take place? How much should the user pay for power? These discretionary

decisions can be ‘‘for sale’’ by the employees.

The organization’s management and employees thrive on power scarcity and there is little

incentive to increase supply or to operate a more efficient or effective service. The legal

aspects of power theft have received attention in some countries. Outdated laws treat theft

as a common crime. Several countries recently have adopted laws governing power theft

and treat it as a special crime.

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The Andhra Pradesh amendments to the Indian Electricity Act (1910) contains punishments

from 6 months to 5 years imprisonment, fines of between 5000 to 50,000 Rupees, and

depriving the thief of electric power for up to 6 years. In Malaysia half-page ads newspapers

warn consumers of the illegality of power theft with fines of up to RM 100,000 and

imprisonment of up to 5 years. The new laws make the punishment for theft much easier to

implement and the fines and penalties imposed a deterrent to future theft. The problem of

arrears or non-payment is a difficult one. Electricity is an essential commodity and a ‘‘no

pay, no electricity’’ policy may not be politically acceptable in some countries.

Disconnection also can be dangerous as a World Bank (1999) study noted, ‘‘In Albania,

consumers with guns y threatened to shoot the utility officials who attempted to disconnect

defaulting customers.’’ The scope of this problem can be so serious that the financial

viability of the organization is jeopardized. Contracting the bill collection to a private

agency may promote some effectiveness in revenue collection.

Alternative methods and places for bill payment may also help. Some power systems have

promoted prepaid cards as a method to ensure payment. However, changing a culture of

non-payment has no easy solutions (Barnes, 2000; Landin, 2001).In some cases those

owing the most money are government agencies, and collecting can confront legal and

political hurdles.

1.7.3 System Change

In the systems where power theft is the highest, electricity sector organizations are state

owned and managed enterprises.

Some power sector state enterprises have operated with substantial efficiency (in

Singapore, for instance), so one cannot argue a case that the public sector is incapable of

running services effectively and efficiently. However, a case can be made that state owned

and operated enterprises are not managed as true businesses and therefore do not try to

optimize profits. The organizations may be intertwined into the political and bureaucratic

structures and processes and there are few incentives to reduce theft .In the Indian case,

theft did not slowly emerge, it has been around for many decades—it is just that nothing

was ever done about it. Political leaders, power consumers and SEB managers and

employees have benefited from the system.

A world trend has been deregulation and the transformation of public sector enterprises into

the private sector. In the past decade many power systems were privatized and now operate

as businesses with shares traded on the stock exchanges (Bacon, 1999).The total power

sector is difficult to privatize into effective private sector enterprises because transmission

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and distribution are natural monopolies, and competition is essential to spur businesses to

be more efficient. National and state level power systems have been transformed in the past

decade and the creation of an independent regulatory commission for electricity has been a

common reform.

The problem of how to deal with technical and non-technical losses is a complex one for

the new commissions. The issues to grapple with include setting levels of ‘‘acceptable

loss,’’ whether utilities should be allowed to pass on theft and other inefficiency costs to

customers, and whether utilities should be penalized if they do not achieve reductions in

T&D and theft. The transformation of electric power systems into more business-like

enterprises means for many countries the elimination of subsidies provided by the state that

kept electricity prices low for consumers.

As prices in poor countries rise to international levels, many consumers are trapped. Their

own income is by local standards—perhaps $2 to $5 per day, but their electricity ARTICLE

IN PRESS 2074 T.B. Smith / Energy Policy 32 (2004) 2067–2076 charges are the same as

for a customer in Los Angeles who earns $80 per day. Under these conditions, consumers

may feel that there is no alternative but to engage in electricity theft or not pay their bills.

Logic and theory suggests that private owned power organizations will be more concerned

with theft than public sector organizations. Contrasting Malaysia’s privatized system with

Thailand’s public enterprise system regarding electricity theft is interesting (Smith,

2003).Both systems have similar T&D losses of around 11%.In 1994 Malaysia divested

Tenaga, the power generation, transmission and distribution enterprise for peninsular

Malaysia.

Government maintains majority ownership, but its shares are traded on the Kuala Lumpur

stock exchange. Independent power producers (IPPs) were permitted from the mid-1990s

to produce power and sell it to Tenaga for distribution. In the Thai case, the EGAT is a

public enterprise that generates and transmits power to two large distribution public

enterprises, the Provincial Electricity Authority (PEA) and the Metropolitan Electricity

Authority (MEA). Attempts to privatize Thai electricity have been discussed for nearly 20

years, but the 32,000 member EGAT employees’ union has vigorously opposed the change.

Electricity theft is not a big issue in Thailand because EGAT, PEA and MEA appear to

have no concerted effort to deal with it. The enterprises make sufficient profits to keep the

government happy and to provide the employees with free electricity as well as a substantial

end of year bonus in EGAT equal to about US$1000 per employee.

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The recent economic crisis severely dented Tenaga’s profitability. Low profits affect the

stock market price of shares forced to run efficiently, Tenaga management turned, in a very

serious way, to the reduction of power theft that causes losses of M$500 million a year.

Caution needs to be exercised about promoting privatization as a panacea for the ills of

inefficiency. The Orissa (India) electricity sector was privatized in 1996 with the

corporatization of the Orissa State Electricity Board, the establishment of the Grid

Corporation of Orissa to manage T&D of electricity and the Orissa Electricity Regulatory

Commission to regulate the system.

The record shows uneven improvement (see Dixit et al., 1998).Power tariffs went up by

76%, T&D losses soared to 45%, and revenue collection was only at 54% of those billed

(Dhume, 1999). 11. Conclusions The evidence points to the increasing levels of power theft

in many countries and the financial losses for some systems are so immense that the utility

is in financial turmoil.

Investment in improving the system and adding additional capacity cannot be undertaken,

loans and payments cannot be met, and the consumer faces increased electricity charges.

Even in efficient systems, theft losses can account for millions of dollars each year in lost

revenue. Electricity theft in its various forms can be reduced and kept in check only by the

strong and assertive action of power sector organizations.

The strategy and the action should be based upon a thorough understanding of the specific

nature of the theft problem. A strong case can be made that each power system (including

consumer’s attitudes and behavior) has its own unique qualities and only by knowing the

system and the problem can effective solutions be designed and implemented.

Since a high level of power theft is linked with corruption, the analysis cannot be confined

to technical and managerial perspectives and needs to be multi-disciplinary in approach.

Theft as an activity in some systems is closely intertwined with governance and with the

social, economic and political environment.

Corruption and electricity theft thrives off each other.

In an overall culture of corruption as a way of life, electricity theft can be reduced to

smoderate levels by technical/engineering methods. But it is an uphill battle to reduce the

electricity theft rate drastically as long as extensive corruption continues. Reduction in

power theft and keeping it within reasonable bounds is more likely to be successful in

systems with a good governance culture. This is because the theft reduction mechanisms

find a friendly environment for initiation and implementation.

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As part of generating and sustaining good governance in communities, electric power

systems have the opportunity to take the lead in promoting sound corporate governance.

The technological innovations make this task easier should the managerial skills and desire

exist. Electric power systems can be restructured to make power sector organizations

operate in competitive environments where efficiency and effectiveness in service delivery.

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Chapter 2

EMBEDDED SYSTEM

2.1 INTRODUCTION

Embedded system is a computer system designed for specific control functions within a

larger system, often with real-time computing constraints. It is embedded as part of a

complete device often including hardware and mechanical parts. By contrast, a general-

purpose computer, such as a personal computer (PC), is designed to be flexible and to meet

a wide range of end-user needs. Embedded systems control many devices in common use

today.

Embedded systems contain processing cores that are typically either microcontrollers or

digital signal processors (DSP). The key characteristic, however, is being dedicated to

handle a particular task. Since the embedded system is dedicated to specific tasks, design

engineers can optimize it to reduce the size and cost of the product and increase the

reliability and performance. Some embedded systems are mass-produced, benefiting from

economies of scale.

Physically, embedded systems range from portable devices such as digital watches and

MP3 players, to large stationary installations like traffic lights, factory controllers, or the

systems controlling nuclear power plants. Complexity varies from low, with a single

microcontroller chip, to very high with multiple units, peripherals and networks mounted

inside a large chassis or enclosure. Embedded systems span all aspects of modern life and

there are many examples of their use.

Telecommunications systems employ numerous embedded systems from telephone

switches for the network to mobile phones at the end-user. Computer networking uses

dedicated routers and network bridges to route data. Consumer electronics include personal

digital assistants (PDAs), mp3 players, mobile phones, videogame consoles, digital

cameras, DVD players, GPS receivers, and printers. Many household appliances, such as

microwave ovens, washing machines and dishwashers, are including embedded systems to

provide flexibility, efficiency and features. Advanced HVAC systems use networked

thermostats to more accurately and efficiently control temperature that can change by time

of day and season. Home automation uses wired- and wireless-networking that can be used

to control lights, climate, security, audio/visual, surveillance, etc., all of which use

embedded devices for sensing and controlling.

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Transportation systems from flight to automobiles increasingly use embedded systems.

New airplanes contain advanced avionics such as inertial guidance systems and GPS

receivers that also have considerable safety requirements. Various electric motors —

brushless DC motors, induction motors and DC motors — are using electric/electronic

motor controllers. Automobiles, electric vehicles, and hybrid vehicles are increasingly

using embedded systems to maximize efficiency and reduce pollution. Other automotive

safety systems include anti-lock braking system (ABS), Electronic Stability Control

(ESC/ESP), traction control (TCS) and automatic four-wheel drive.

Medical equipment is continuing to advance with more embedded systems for vital signs

monitoring, electronic stethoscopes for amplifying sounds, and various medical imaging

(PET, SPECT, CT, and MRI) for non-invasive internal inspections.

Embedded systems are especially suited for use in transportation, fire safety, safety and

security, medical applications and life critical systems as these systems can be isolated from

hacking and thus be more reliable. For fire safety, the systems can be designed to have

greater ability to handle higher temperatures and continue to operate. In dealing with

security, the embedded systems can be self-sufficient and be able to deal with cut electrical

and communication systems.

In addition to commonly described embedded systems based on small computers, a new

class of miniature wireless devices called motes are quickly gaining popularity as the field

of wireless sensor networking rises. Wireless sensor networking, WSN, makes use of

miniaturization made possible by advanced IC design to couple full wireless subsystems to

sophisticated sensors, enabling people and companies to measure a myriad of things in the

physical world and act on this information through IT monitoring and control systems.

These motes are completely self-contained, and will typically run off a battery source for

many years before the batteries need to be changed or charged.

2.2 CHARACTERSTICS

1. Embedded systems are designed to do some specific task, rather than be a general-

purpose computer for multiple tasks. Some also have time performance constraints that

must be met, for reasons such as safety and usability; others may have low or no

performance requirements, allowing the system hardware to be simplified to reduce costs.

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2. Embedded systems are not always standalone devices. Many embedded systems 2consist

of small, computerized parts within a larger device that serves a more general purpose.

3. The program instructions written for embedded systems are referred to as firmware, and

are stored in read-only memory or Flash memory chips. They run with limited computer

hardware resources: little memory, small

2.3 USER INTERFACE

Embedded systems range from no user interface at all dedicated only to one task to complex

graphical user interfaces that resemble modern computer desktop operating systems.

Simple embedded devices use buttons, LEDs, graphic or character LCDs (for example

popular HD44780 LCD) with a simple menu system.

More sophisticated devices which use a graphical screen with touch sensing or screen-edge

buttons provide flexibility while minimizing space used: the meaning of the buttons can

change with the screen, and selection involves the natural behavior of pointing at what's

desired. Handheld systems often have a screen with a "joystick button" for a pointing

devices.

2.4 TOOLS REQUIRED

As with other software, embedded system designers use compilers, assemblers, and

debuggers to develop embedded system software. However, they may also use some more

specific tools.

In circuit debugger or emulators (see next section)

Utilities to add a checksum or CRC to a program, so the embedded system can check if

the program is valid.

For systems using digital signal processing, developers may use a math workbench such

as Scilab /Scicos, MATLAB / Simulink, EICASLAB, Mathcad, Mathematical, or

Flowstone DSP to simulate the mathematics. They might also use libraries for both the

host and target which eliminates developing DSP routines as done in DSPnano RTOS

and Unison Operating System.

A model based development tool like VisSim lets you create and simulate graphical

data flow and UML State chart diagrams of components like digital filters, motor

controllers, communication protocol decoding and multi-rate tasks. Interrupt handlers

can also be created graphically. After simulation, you can automatically generate C-

code to the VisSim RTOS which handles the main control task and preemption of

background tasks, as well as automatic setup and programming of on-chip peripherals.

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Custom compilers and linkers may be used to improve optimization for the particular

hardware.

An embedded system may have its own special language or design tool, or add

enhancements to an existing language such as Forth or Basic.

Another alternative is to add a real-time operating system or embedded operating

system, which may have DSP capabilities like DSPnano RTOS.

Modeling and code generating tools often based on state machines

Software tools can come from several sources:

Software companies that specialize in the embedded market

Ported from the GNU software development tools

Sometimes, development tools for a personal computer can be used if the embedded

processor is a close relative to a common PC processor

As the complexity of embedded systems grows, higher level tools and operating

systems are migrating into machinery where it makes sense. For example, cellphones,

personal digital assistants and other consumer computers often need significant

software that is purchased or provided by a person other than the manufacturer of the

electronics. In these systems, an open programming environment such as Linux,

NetBSD, OSGi or Embedded Java is required so that the third-party software provider

can sell to a large market.

2.4.1 Processor in Embedded System

Embedded processors can be broken into two broad categories: ordinary microprocessors

(μP) and microcontrollers (μC), which have many more peripherals on chip, reducing cost

and size. Contrasting to the personal computer and server markets, a fairly large number of

basic CPU architectures are used; there are Von Neumann as well as various degrees of

Harvard architectures, RISC as well as non-RISC and VLIW; word lengths vary from 4-bit

to 64-bits and beyond (mainly in DSP processors) although the most typical remain 8/16-

bit. Most architectures come in a large number of different variants and shapes, many of

which are also manufactured by several different companies.

2.4.2 Microprocessor

A microprocessor incorporates the functions of a computer's central processing unit (CPU)

on a single integrated circuit, (IC) or at most a few integrated circuits. It is a multipurpose,

programmable device that accepts digital data as input, processes it according to

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instructions stored in its memory, and provides results as output. It is an example of

sequential digital logic, as it has internal memory.

Microprocessors operate on numbers and symbols represented in the binary numeral

system.

The advent of low-cost computers on integrated circuits has transformed modern society.

General-purpose microprocessors in personal computers are used for computation, text

editing, multimedia display, and communication over the Internet. Many more

microprocessors are part of embedded systems, providing digital control of a myriad of

objects from appliances to automobiles to cellular phones and industrial process control.

Thousands of items that were traditionally not computer-related include microprocessors.

These include large and small household appliances, cars (and their accessory equipment

units), car keys, tools and test instruments, toys, light switches/dimmers and electrical

circuit breakers, smoke alarms, battery packs, and hi-fi audio/visual components

(from DVD players to phonograph turntables.) Such products as cellular telephones, DVD

video system and ATSC HDTV broadcast system fundamentally require consumer devices

with powerful, low-cost, microprocessors. Increasingly stringent pollution control

standards effectively require automobile manufacturers to use microprocessor engine

management systems, to allow optimal control of emissions over widely varying operating

conditions of an automobile. Non-programmable controls would require complex, bulky,

or costly implementation to achieve the results possible with a microprocessor. A

microprocessor control program can be easily tailored to different needs of a product line,

allowing upgrades in performance with minimal redesign of the product. Different features

can be implemented in different models of a product line at negligible production cost.

Microprocessor control of a system can provide control strategies that would be

impractical to implement using electromechanical controls or purpose-built electronic

controls. For example, an engine control system in an automobile can adjust ignition timing

based on engine speed, load on the engine, ambient temperature, and any observed

tendency for knocking - allowing an automobile to operate on a range of fuel grades.

2.4.3 Microcontroller

A microcontroller (sometimes abbreviated µC, uC or MCU) is a small computer on a single

integrated circuit containing a processor core, memory, and programmable input/output

peripherals. Program memory in the form of NOR flash or OTP ROM is also often included

on chip, as well as a typically small amount of RAM. Microcontrollers are designed for

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embedded applications, in contrast to the microprocessors used in personal computers or

other general purpose applications.

Microcontrollers are used in automatically controlled products and devices, such as

automobile engine control systems, implantable medical devices, remote controls, office

machines, appliances, power tools, toys and other embedded systems. By reducing the size

and cost compared to a design that uses a separate microprocessor, memory, and

input/output devices, microcontrollers make it economical to digitally control even more

devices and processes. Mixed signal microcontrollers are common, integrating analog

components needed to control non-digital electronic systems. Some microcontrollers may

use four-bit words and operate at clock rate frequencies as low as 4 kHz, for low power

consumption (mill watts or microwatts). They will generally have the ability to retain

functionality while waiting for an event such as a button press or other interrupt; power

consumption while sleeping (CPU clock and most peripherals off) may be just Nano watts,

making many of them well suited for long lasting battery applications. Other

microcontrollers may serve performance-critical roles, where they may need to act more

like a digital signal processor.

A microcontroller can be considered a self-contained system with a processor, memory and

peripherals and can be used as an embedded system.[5]The majority of microcontrollers in

use today are embedded in other machinery, such as automobiles, telephones, appliances,

and peripherals for computer systems. While some embedded systems are very

sophisticated, many have minimal requirements for memory and program length, with no

operating system, and low software complexity. Typical input and output devices include

switches, relays, solenoids, LEDs, small or custom LCD displays, radio frequency devices,

and sensors for data such as temperature, humidity, light level etc. Embedded systems

usually have no keyboard, screen, disks, printers, or other recognizable I/O devices of a

personal computer, and may lack human interaction devices of any kind.

2.4.3.1 Interrupts in microcontroller

Microcontrollers must provide real time (predictable, though not necessarily fast) response

to events in the embedded system they are controlling. When certain events occur, an

interrupt system can signal the processor to suspend processing the current instruction

sequence and to begin an interrupt service routine (ISR, or "interrupt handler").

The ISR will perform any processing required based on the source of the interrupt before

returning to the original instruction sequence. Possible interrupt sources are device

dependent, and often include events such as an internal timer overflow, completing an

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analog to digital conversion, a logic level change on an input such as from a button being

pressed, and data received on a communication link. Where power consumption is

important as in battery operated devices, interrupts may also wake a microcontroller from

a low power sleep state where the processor is halted until required to do something by a

peripheral even.

2.4.3.2 Programs in microcontroller

Typically microcontroller programs must fit in the available on-chip program memory,

since it would be costly to provide a system with external, expandable, memory. Compilers

and assemblers are used to convert high-level language and assembler language codes into

a compact machine code for storage in the microcontroller's memory. Depending on the

device, the program memory may be permanent, read-only memory that can only be

programmed at the factory, or program memory may be field-alterable flash or erasable

read-only memory.

Manufacturers have often produced special versions of their microcontrollers in order to

help the hardware and software development of the target system. Originally these included

EPROM versions that have a "window" on the top of the device through which program

memory can be erased by ultraviolet light, ready for reprogramming after a programming

("burn") and test cycle. Since 1998, EPROM versions are rare and have been replaced by

EEPROM and flash, which are easier to use (can be erased electronically) and cheaper to

manufacture. Other versions may be available where the ROM is accessed as an external

device rather than as internal memory, however these are becoming increasingly rare due

to the widespread availability of cheap microcontroller programmers. The use of field-

programmable devices on a microcontroller may allow field update of the firmware or

permit late factory revisions to products that have been assembled but not yet shipped.

Programmable memory also reduces the lead time required for deployment of a new

product. Where hundreds of thousands of identical devices are required, using parts

programmed at the time of manufacture can be an economical option. These "mask

programmed" parts have the program laid down in the same way as the logic of the chip,

at the same time. A customizable microcontroller incorporates a block of digital logic that

can be personalized in order to provide additional processing capability, peripherals and

interfaces that are adapted to the requirements of the application. For example, the

AT91CAP from Atmel has a block of logic that can be customized during manufacturer

according to user requirements.

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2.4.3.3 Other features of microcontroller

Microcontrollers usually contain from several to dozens of general purpose input/output

pins (GPIO). GPIO pins are software configurable to either an input or an output state.

When GPIO pins are configured to an input state, they are often used to read sensors or

external signals. Configured to the output state, GPIO pins can drive external devices such

as LEDs or motors.

Many embedded systems need to read sensors that produce analog signals. This is the

purpose of the analog-to-digital converter (ADC). Since processors are built to interpret

and process digital data, i.e. 1s and 0s, they are not able to do anything with the analog

signals that may be sent to it by a device. So the analog to digital converter is used to

convert the incoming data into a form that the processor can recognize. A less common

feature on some microcontrollers is a digital-to-analog converter (DAC) that allows the

processor to output analog signals or voltage levels.

A dedicated Pulse Width Modulation (PWM) block makes it possible for the CPU to

control power converters, resistive loads, motors, etc., without using lots of CPU resources

in tight timer loops.

Universal Asynchronous Receiver/Transmitter (UART) block makes it possible to receive

and transmit data over a serial line with very little load on the CPU. Dedicated on-chip

hardware also often includes capabilities to communicate with other devices (chips) in

digital formats such as I²C and Serial Peripheral Interface (SPI).

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Chapter 3

ENERGY THEFT DETECTION: THEORY AND WORKING

MODEL

3.1 PROJECT IDEA

The aim of this project, as the title name suggests, is to detect the power theft that occurs

in our daily lives. We come across such a situation many times in our daily lives where

power and electricity get routed to some other destination through various means like cross-

wiring etc. Our idea to detect power theft is by using two meters, one at the load end and

one for the detection, which would indicate if any discrepancy occurs in the power supply

and if detected, would result in power supply cut-off immediately.

3.2 CIRCUIT DIAGRAM

Fig. 3.1.Functional Block Diagram of Energy Theft Detector

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3.3 WORKING

This project consists of mainly two sections. One section consists of energy meter, isolator

and receiver + comparator situated on our supply pole and the one consists of energy meter

isolator and transmitter, situated in our homes.

The energy meter 1 & 2 can measure the energy by measuring voltage and current. Voltage

can measure directly with the help of voltmeter provided on the energy meter but for

measuring current it requires a Current transformer (C.T.). The C.T. can measure current

by measuring magnetic field induced from a current carrying thick copper wire using a coil.

Energy meter consists of four LED’s to show the status. One LED (transparent red LED)

blinks with a constant time interval. This time interval reduces with increase in LOAD.

The energy meter at our home measures the energy consumed by different LOADs. The

output from energy meter (from blinking LED) is given to transmitter section through

isolator. Isolator consists of a relay and a driver for switching it by energy meters output.

The isolator prevents the transmitter section from high voltage output of energy meter. The

isolator output is used to drive one out of four inputs of the transmitter. This signal is

decoded using encoder IC HT12E and transmitted using RF transmitter module.

At the pole the energy meter 1 will measure the supplied electric energy to the home by

similar method, by measuring voltage and current using C.T. The output of energy meter

is fed to the trigger input of the receiver section through isolator. This isolator also consists

of a relay and a transistor driver circuit.

The receiver section consists of RF receiver to receive the signal transmitted from the home

transmitter section. It consists of various LED’s to show the status. LED 5(orange LED)

will blink to show proper transmission from transmitter at home to the receiver at pole. If

this LED L5 does not blink, it indicates that there is a problem in the RF link between Tx

and Rx. LED 4 is by default ON. The triggered input wills ON the LED L3. The next pulse

received from the transmitter section OFF LED L3.Since the energy meter at pole measure

the same energy as measured by the home energy meter i.e. the energy delivered to the

LOAD (various appliances). The pulse rate of blinking LED’s of both energy meters is

same. In case of any theft i.e. bypassing the home energy meter or taking energy before our

home energy meter the pulse rate of blinking LED of the home energy meter will reduce

while the pulse rate of blinking LED at the pole energy meter will remain same.

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It will lead to continuous ON of LED L3. As LED L3 continuously glows for more than

one minute it will switch OFF the relay to cut the supply to the home. At this situation LED

L4 turn OFF and LED’s L2 and L3 will glow continuously to show the occurrence of fault.

Internal description of the RF Transmitter and Receiver is:-

1. RF Transmitter

The RF Tx consists of RF Tx module, an encoder i.e. HT12E, four switches and the

transmitting antenna. The energy meter 2 is connected to RF Tx with the help of Isolator.

Isolators are nothing but relay circuit consists of a resistor, transistor and an inductor

connected to 12V supply and of course relay. RF Tx has four switches viz. S1, S2, S3 and

S4. Isolator relay is connected to S4 switch of the RF Tx. The main function of RF Tx is to

change the state of LED L4. If the LED is ON it will turn it OFF and if it is OFF it will

turn it ON. All the switches is then connected to the encoder HT12E whose output drives

the RF Tx module unit and then it is transmitted with the help of an antenna. The transmitter

module accepts serial data. The encoder IC takes in parallel data at the TX side packages it

into serial format and then transmits it with the help of a RF transmitter module. At the RX

end, the decoder IC receives the signal via the RF receiver module, decodes the serial data

and reproduces the original data in the parallel format.

Fig. 3.2. Encoder HT 12E

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The 212 encoders are a series of CMOS LSI’s for remote control system applications. They

are capable of encoding information which consists of N address bits and 12_N data bits.

Each address/data input can be set to one of the two logic states. The programmed

addresses/data are transmitted together with the header bits via an RF or an infrared

transmission medium upon receipt of a trigger signal. The capability to select a TE trigger

on the HT12E or a DATA trigger on the HT12A further enhances the application flexibility

of the 212 series of encoders. The HT12A additionally provides a 38 kHz carrier for

infrared systems.

Fig. 3.3. Address and Data of Micro Controller

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Note: D8~D11 are all data input and transmission enable pins of the HT12A.

TE is a transmission enable pin of the HT12E

The 2^12 series of encoders begin a 4-word transmission cycle upon receipt of a

transmission enable (TE for the HT12E or D8~D11 for the HT12A, active low). This cycle

will repeat itself as long as the transmission enable (TE or D8~D11) is held low. Once the

transmission enables returns high the encoder output completes its final cycle and then

stops as shown below.

Fig. 3.4. Transmission Timing for the HT12E

The TX433 wireless RF transmitter uses on/off keying to transmit data to the matching

receiver, RX433. The data input “keys” the saw resonator in the transmitter when the input

is +3 volts or greater, AM modulating the data onto the 433 MHz carrier. The data is then

demodulated by the receiver, which accurately reproduces the original data. The data input

is CMOS level Compatible when the unit is run on +5 volts.When driving with a CMOS

input, there must be enough level to achieve at least 3V on the data input, 5V is preferable.

This is due to the start-up time of the oscillator needing to be fast to accurately reproduce

your data.

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If the voltage is too low, the oscillator will not start fast enough to accurately reproduce

your data, especially at higher data rates. Luckily not much drive is needed, so this should

be easy since it is 22K ohms of load. Almost any CMOS output will drive this without any

problems. There are some CMOS outputs which have very little drive capability which may

not work, so testing the voltage at the data input may be a wise choice if you are having

problems.

Fig. 3.5. 433 MHz Transmitter

2. RF Receiver

This section consists of five LED’s (four yellow and one orange), RF Rx module, decoder

HT 12D, and PIC microcontroller 16F73 and a receiving antenna. Antenna receives the

transmitted signal and that received signal is then fed to the RF Rx module whose output

is then provided to the decoder HT12D and then to the PIC 16F73.

The receiver shown in Figure also contains just one transistor. It is biased to act as a

regenerative oscillator, in which the received antenna signal causes the transistor to switch

to high amplification, thereby automatically arranging the signal detection. Next, the ‘raw’

demodulated signal is amplified and shaped-up by op-amps. The result is a fairly clean

digital signal at the output of the receiver. The logic high level is at about 2/3 of the supply

voltage, i.e., between 3 V and 4.5 V. The range of the simple system shown in Figures is

much smaller than that of more expensive units, mainly because of the low transmit power

(approx. 1 mW) and the relative insensitivity and wide-band nature of the receiver.

Moreover, amplitude-modulated noise is not suppressed in any way.

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Fig. 3.6. 433 MHz RF Receiver

The 2^12decoders are a series of CMOS LSI’s for remote control system applications. They

are paired with Holtek’s 2^12series of encoders (refer to the encoder/decoder cross

reference table.

For proper operation, a pair of encoder/decoder with the same number of addresses and

data format should be chosen. The decoders receive serial addresses and data from a

programmed 2^12 series of encoders that are transmitted by a carrier using an RF or an IR

transmission medium. They compare the serial input data three times continuously with

their local addresses.

If no error or unmatched codes are found, the input data codes are decoded and then

transferred to the output pins. The VT pin also goes high to indicate a valid transmission.

The 2^12 series of decoders are capable of decoding in formations that consist of N bits of

address and 12_N bits of data. Of this series, the HT12D is arranged to provide 8 address

bits and 4 data bits, and HT12F is used to decode 12 bits of address information.

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Fig. 3.7. HT12D Controller

For proper operation, a pair of encoder/decoder with the same number of addresses and

data format should be chosen. The decoders receive serial addresses and data from a

programmed 2^12 series of encoders that are transmitted by a carrier using an RF or an IR

transmission medium. They compare the serial input data three times continuously with

their local addresses. The decoders receive serial addresses and data from a programmed

2^12 series of encoders that are transmitted by a carrier using an RF or an IR transmission

medium. They compare the serial input data three times continuously with their local

addresses.

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Fig. 3.8. HT12D Pin Diagram

The 2^12 series of decoders provides various combinations of addresses and data pins in

different packages so as to pair with the 2^ 12 series of encoders. The decoders receive data

that are transmitted by an encoder and interpret the first N bits of code period as addresses

and the last 12_N bits as data, where N is the address code number. A signal on the DIN

pin activates the oscillator which in turn decodes the incoming address and data. The

decoders will then check the received address three times continuously. If the received

address codes all match the contents of the decoder’s local address, the 12_N bits of data

are decoded to activate the output pins and the VT pin is set high to indicate a valid

transmission. This will last unless the address code is incorrect or no signal is received. The

output of the VT pin is high only when the transmission is valid. Otherwise it is always

low. Of the 2^12 series of decoders, the HT12F has no data output pin but its VT pin can

be used as a momentary data output. The HT12D, on the other hand, provides 4 latch type

data pins whose data remain unchanged until new data are received. The decoders will then

check the received address three times continuously. If the received address codes all match

the contents of the decoder’s local address, the 12_N bits of data are decoded to activate

the output pins and the VT pin is set high to indicate a valid transmission. This will last

unless the address code is incorrect or no signal is received. The output of the VT pin is

high only when the transmission is valid. Otherwise it is always low. Of the 2^12 series of

decoders, the HT12F has no data output pin but its VT pin can be used as a momentary data

output. The HT12D, on the other hand, provides 4 latch type data pins whose data remain

unchanged until new data are received.

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Fig.3.9. PIC16F73 Block Diagram

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3.4 CODING OF TRANSMITTER

int flag=0;

int counter=0;

void main()

{

PORTC.bit4=1

PORTC.bit5=0;

PORTC.bit6

PORTC.bit7=0;

While(1)

{

If(PORTB.bit0==1)

{

While (PORTB.bit0==1)

{

}

If(flag==1)

{

PORTC.bit6=1;

Counter=counter+1;

Delay..ms(1000);

}

If(flag==0)

{

Flag=1:

PORTC.bit5=1;

Delay..ms(200);

}

If(PORTC.bit0==1||PORTC.bit3==1)

{

While(PORTC.bit==1||PORTC.bit==1)

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{

}

flag=0;

PORTC.bit5=0;

PORTC.bit6=0;

}

If(counter>4)

{

goto end

}

}

end:

PORTC.bit4=0;

PORTC.bit5=0;

PORTC.bit6=0;

PORTC.bit7=1;

}

3.5 RELAYS

A relay is usually an electromechanical device that is actuated by an electrical current. The

current flowing in one circuit causes the opening or closing of another circuit. Relays are

like remote control switches and are used in many applications because of their relative

simplicity, long life, and proven high reliability. They are used in a wide variety of

applications throughout industry, such as in telephone exchanges, digital computers and

automation systems.

3.5.1 How relay works?

All relays contain a sensing unit, the electric coil, which is powered by AC or DC current.

When the applied current or voltage exceeds a threshold value, the coil activates the

armature, which operates either to close the open contacts or to open the closed contacts.

When a power is supplied to the coil, it generates a magnetic force that actuates the switch

mechanism. The magnetic force is, in effect, relaying the action from one circuit to another.

The first circuit is called the control circuit; the second is called the load circuit. A relay is

usually an electromechanical device that is actuated by an electrical current. The current

flowing in one circuit causes the opening or closing of another circuit.

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Fig. 3.10. Working of relay

3.5.2 Types of relay

1 Electromechanical Relay

2 Solid State Relay

1 Electromechanical Relay

Electromechanical relays have moving parts, whereas solid state relays have no moving

parts. Advantages of Electromechanical relays include lower cost, no heat sink is required,

multiple poles are available, and they can switch AC or DC with equal ease. They are also

known as General Purpose Relay. The general-purpose relay is rated by the amount of

current its switch contacts can handle. Most versions of the general-purpose relay have one

to eight poles and can be single or double throw. These are found in computers, copy

machines, and other consumer electronic equipment and appliances.

Power Relay: The power relay is capable of handling larger power loads – 10-50

amperes or more

Contactor: A special type of high power relay, it’s used mainly to control high voltages

and currents in industrial electrical applications. Because of these high power

requirements, contactors always have double-make contacts.

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Time-Delay Relay: The contacts might not open or close until sometime interval after

the coil has been energized. This is called delay-on-operate. Delay-on-release means

that the contacts will remain in their actuated position until some interval after the

power has been removed from the coil. A third delay is called interval timing. Contacts

revert to their alternate position at a specific interval of time after the coil has been

energized. The timing of these actions may be a fixed parameter of the relay, or adjusted

by a knob on the relay itself, or remotely adjusted through an external circuit.

2 Solid State Relay

These active semiconductor devices use light instead of magnetism to actuate a switch. The

light comes from an LED, or light emitting diode. When control power is applied to the

device’s output, the light is turned on and shines across an open space. On the load side of

this space, a part of the device senses the presence of the light, and triggers a solid state

switch that either opens or closes the circuit under control. Often, solid state relays are used

where the circuit under control must be protected from the introduction of electrical noises.

Advantages of Solid State Relays include low EMI/RFI, long life, no moving parts, no

contact bounce, and fast response. The drawback to using a solid state relay is that it can

only accomplish single pole switching.

3.6 POWER SUPPLY

Power supply can be defined as electronic equipment, which is a stable source of D.C.

power for electronic circuits.

Power supply can be classified into two major categories:

Unregulated power supply

Regulated power supply

3.6.1 Unregulated Power Supply

These power supplies, supply power to the load but do not take into variation of power

supply output voltage or current with respect to the change in A.C. mains voltage, load

current or temperature variations. In other words, we can say that the output voltage or

current of an unregulated power supply changes with the change in A.C .mains voltage,

load current and temperature.

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Fig.3.11. Unregulated power supply

3.6.2 Regulated power supply

These power supplies are regulated over the change in source voltage or load current i.e.

its output remain stable.

Regulated power supplies are of two types: -

Current Regulated power supplies

These are constant current supplies in spite of change in load or input voltage

Voltage Regulated power supplies

These supplies supply constant output voltage with respect to the variation in load or source

input voltage

Fig.3.12. Regulated power supply

Fig. 3.13. Circuit of regulated power supply with half wave rectifier and ic-7809 as a

regulator

C20.1uF

IN

COM

OUT

C1

1000uFD4D3D2D1

T110TO1


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