gsm based energy meter doc

7/27/2019 GSM Based Energy Meter Doc

1/125

INDEX

TOPICS

Certificates

Acknowledgement........

CHAPTE !" INTOD#CTION

!.! Introd$ction of t%e &ro'ect

!.( Pro'ect o)er)iew...

!.* T%esis

CHAPTE (" E+,EDDED S-STE+S

(.! Introd$ction to emedded s/stems

(.( Need of emedded s/stems...

(.* E0&lanation of emedded s/stems...

(.1 A&&lications of emedded s/stems

CHAPTE *" HAD2AE DESCIPTION

*.! Introd$ction wit% lock diagram

*.( +icrocontroller.

*.* eg$lated &ower s$&&l/...

*.1 3ED indicator........

*.4 Energ/ +eter.........

*.5 O&toco$&ler...

*.6 7S+...

1


2/125

*.8 ela/...

*.9 3CD....

*.!: Tam&er switc%...

CHAPTE 1" SO;T2AE DESCIPTION

1.! E0&ress PC,

1.( PIC C Com&iler.

1.* Prote$s software

1.1 Proced$ral ste&s for com&ilation< sim$lation and d$m&ing..

CHAPTE 4" PO=ECT DESCIPTION

CHAPTE 5" AD>ANTA7ES< DISAD>ANTA7ES AND APP3ICATIONS

CHAPTE 6" ES#3TS< CONC3#SION< ;#T#E POSPECTS

E;EENCES

2


3/125

CHAPTE !" INTOD#CTION

!.! Introd$ction"

The purpose of this project is to design a system which helps in remote monitoring and control

of the Domestic Energy meter through simply sending an SMS. This system enables the Electricity

Department to read the meter readings regularly without the person visiting each house. This can be

achieved by the use of Microcontroller unit that continuously monitors and records the Energy Meter

readings in its permanent (non-volatile memory location. This system also ma!es use of a "SM

modem for remote monitoring and control of Energy Meter.

The modules in the project are# "SM modem for establishing communication between system

at house and electricity department$ Energy meter which continuously gives usage details$ %&D to

display current reading of meter$ 'elay to disconnect the power in case of nonpayment of bill.

The Microcontroller based system continuously records the readings and the live meter

reading and will be sent to the Electricity department on reuest. This system also can be used to

disconnect the power supply to the house in case of non-payment of electricity bills. ) dedicated "SM

modem with S*M card is reuired for each energy meter. The Microcontroller which acts as a

controlling unit of the whole system is loaded with intelligent software programmed using Embedded

& language.

;eat$res"

+. ,rovides user friendly remote energy meter monitoring.

. Supports controlling of meter.

. &an be controlled anywhere in the world.

/. 0on-volatile memory based energy-reading storing.

1. )uto disconnect feature.

!.( Pro'ect O)er)iew"

)n embedded system is a combination of software and hardware to perform a

dedicated tas!. Some of the main devices used in embedded products are Microprocessors and

Microcontrollers.

3


4/125

Microprocessors are commonly referred to as general purpose processors as they

simply accept the inputs$ process it and give the output. *n contrast$ a microcontroller not only accepts

the data as inputs but also manipulates it$ interfaces the data with various devices$ controls the data

and thus finally gives the result.

The project 2 Energ/ +eter monitoring and control s/stem $sing S+S

tec%nolog/3 using +45677) Microcontroller is an e8clusive project that can be used

!.* T%esis O)er)iew"

The thesis e8plains the implementation of 2 Energ/ +eter monitoring and

control s/stem $sing S+S tec%nolog/3 using +45677) microcontroller. The organi9ation of the

thesis is e8plained here with#

C%a&ter ! ,resents introduction to the overall thesis and the overview of the project. *n the projectoverview a brief introduction of microcontrollers$ energy meter and its applications are discussed.

C%a&ter ( ,resents the topic embedded systems. *t e8plains the about what is embedded systems$

need for embedded systems$ e8planation of it along with its applications.

C%a&ter * ,resents the hardware description. *t deals with the bloc! diagram of the project and

e8plains the purpose of each bloc!. *n the same chapter the e8planation of microcontrollers$ power

supplies$ energy meter$ %&D$ "SM modem$ tamper switch$ 'elay are considered.

C%a&ter 1 ,resents the software description. *t e8plains the implementation of the project using ,*&

& &ompiler software.

C%a&ter 4 &resents the project description along with energy meter$ %&D$ "SM modem$ tamper

switch$ and 'elay modules interfacing to microcontroller.

C%a&ter 5 ,resents the advantages$ disadvantages and applications of the project.

C%a&ter 6 ,resents the results$ conclusion and future scope of the project.

4


5/125

CHAPTE (" E+,EDDED S-STE+S

(.! Emedded S/stems"

)n embedded system is a computer system designed to perform one or a few dedicated

functions often with real-time computing constraints. *t is embedded as part of a complete device

often including hardware and mechanical parts. :y contrast$ a general-purpose computer$ such as a

personal computer (,&$ is designed to be fle8ible and to meet a wide range of end-user needs.

Embedded systems control many devices in common use today.

Embedded systems are controlled by one or more main processing cores that are

typically either microcontrollers or digital signal processors (DS,. The !ey characteristic$ however$ is

being dedicated to handle a particular tas!$ which may reuire very powerful processors. 5or e8ample$

air traffic control systems may usefully be viewed as embedded$ even though they involve mainframe

computers and dedicated regional and national networ!s between airports and radar sites. (Each radar

probably includes one or more embedded systems of its own.

Since the embedded system is dedicated to specific tas!s$ design engineers can

optimi9e it to reduce the si9e and cost of the product and increase the reliability and performance.

Some embedded systems are mass-produced$ benefiting from economies of scale.

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

M, players$ to large stationary installations li!e traffic lights$ factory controllers$ or the systems

controlling nuclear power plants. &omple8ity varies from low$ with a single microcontroller chip$ to

very high with multiple units$ peripherals and networ!s mounted inside a large chassis or enclosure.

*n general$ ;embedded system; is not a strictly definable term$ as most systems have

some element of e8tensibility or programmability. 5or e8ample$ handheld computers share some

elements with embedded systems such as the operating systems and microprocessors which power

them$ but they allow different applications to be loaded and peripherals to be connected. Moreover$

even systems which don


6/125

;ig (.!"A modern e0am&le of emedded s/stem

%abeled parts include microprocessor (/$ ')M (4$ flash memory (7.Embedded

systems programming is not li!e normal ,& programming. *n many ways$ programming for an

embedded system is li!e programming ,& +1 years ago. The hardware for the system is usually

chosen to ma!e the device as cheap as possible. Spending an e8tra dollar a unit in order to ma!e

things easier to program can cost millions. >iring a programmer for an e8tra month is cheap in

comparison. This means the programmer must ma!e do with slow processors and low memory$ while

at the same time battling a need for efficiency not seen in most ,& applications. :elow is a list of

issues specific to the embedded field.

(.!.! Histor/"

*n the earliest years of computers in the +?@A/@s$ computers were sometimes

dedicated to a single tas!$ but were far too large and e8pensive for most !inds of tas!s performed by

embedded computers of today. =ver time however$ the concept ofprogrammable controllersevolved

from traditional electromechanicalseuencers$ via solid state devices$ to the use of computertechnology.

=ne of the first recogni9ably modern embedded systems was the )pollo "uidance

&omputer$ developed by &harles Star! Draperat the M*T *nstrumentation %aboratory. )t the project


7/125

early mass-produced embedded system was the )utonetics D-+7 guidance computer for

the Minuteman missile$ released in +?4+. *t was built from transistorlogicand had ahard dis!for

main memory. Bhen the Minuteman ** went into production in +?44$ the D-+7 was replaced with a

new computer that was the first high-volume use of integrated circuits.

(.!.( Tools"

Embedded development ma!es up a small fraction of total programming. There


8/125

5or e8ample$ most embedded processors do not have hardware 5,Cs (5loating-,oint ,rocessing

Cnit. These resources either need to be emulated in software$ or avoided altogether.

(.!.1 eal Time Iss$es"

Embedded systems freuently control hardware$ and must be able to respond to themin real time. 5ailure to do so could cause inaccuracy in measurements$ or even damage hardware such

as motors. This is made even more difficult by the lac! of resources available. )lmost all embedded

systems need to be able to prioriti9e some tas!s over others$ and to be able to put offs!ip low priority

tas!s such as C* in favor of high priority tas!s li!e hardware control.

(.( Need ;or Emedded S/stems"

The uses of embedded systems are virtually limitless$ because every day new products

are introduced to the mar!et that utili9es embedded computers in novel ways. *n recent years$

hardware such as microprocessors$ microcontrollers$ and 5,") chips have become much cheaper. So

when implementing a new form of control$ it


9/125

)n in-circuit debugger (*&D$ a hardware device that connects to the microprocessor via a

T)" or 0e8us interface. This allows the operation of the microprocessor to be controlled

e8ternally$ but is typically restricted to specific debugging capabilities in the processor.

)n in-circuit emulator replaces the microprocessor with a simulated euivalent$ providing full

control over all aspects of the microprocessor.

) complete emulator provides a simulation of all aspects of the hardware$ allowing all of it to

be controlled and modified and allowing debugging on a normal ,&.

Cnless restricted to e8ternal debugging$ the programmer can typically load and run software

through the tools$ view the code running in the processor$ and start or stop its operation. The

view of the code may be as assembly code or source-code.

:ecause an embedded system is often composed of a wide variety of elements$ the

debugging strategy may vary. 5or instance$ debugging a software(and microprocessor centric

embedded system is different from debugging an embedded system where most of the processing is

performed by peripherals (DS,$ 5,")$ co-processor. )n increasing number of embedded systems

today use more than one single processor core. ) common problem with multi-core development is

the proper synchroni9ation of software e8ecution. *n such a case$ the embedded system design may

wish to chec! the data traffic on the busses between the processor cores$ which reuires very low-

level debugging$ at signalbus level$ with a logic analy9er$ for instance.

(.(.( eliailit/"

Embedded systems often reside in machines that are e8pected to run continuously for

years without errors and in some cases recover by them selves if an error occurs. Therefore the

software is usually developed and tested more carefully than that for personal computers$ and

unreliable mechanical moving parts such as dis! drives$ switches or buttons are avoided.

Specific reliability issues may include#

The system cannot safely be shut down for repair$ or it is too inaccessible to repair. E8amples

include space systems$ undersea cables$ navigational beacons$ bore-hole systems$ and

automobiles.

The system must be !ept running for safety reasons. ;%imp modes; are less tolerable. =ften

bac!ups are selected by an operator. E8amples include aircraft navigation$ reactor control

9


10/125

systems$ safety-critical chemical factory controls$ train signals$ engines on single-engine

aircraft.

The system will lose large amounts of money when shut down# Telephone switches$ factory

controls$ bridge and elevator controls$ funds transfer and mar!et ma!ing$ automated sales and

service.

) variety of techniues are used$ sometimes in combination$ to recover from errorsF

both software bugs such as memory lea!s$ and also soft errors in the hardware#

Batchdog timer that resets the computer unless the software periodically notifies the watchdog

Subsystems with redundant spares that can be switched over to

software ;limp modes; that provide partial function

Designing with a Trusted &omputing :ase (T&: architectureG4H ensures a highly secure I

reliable system environment

)n Embedded >ypervisor is able to provide secure encapsulation for any subsystem

component$ so that a compromised software component cannot interfere with other

subsystems$ or privileged-level system software. This encapsulation !eeps faults from

propagating from one subsystem to another$ improving reliability. This may also allow a

subsystem to be automatically shut down and restarted on fault detection.

*mmunity )ware ,rogramming

(.* E0&lanation of Emedded S/stems"

(.*.! Software Arc%itect$re"

There are several different types of software architecture in common use.

Simple &ontrol %oop#

*n this design$ the software simply has a loop. The loop calls subroutines$ each of which

manages a part of the hardware or software.

*nterrupt &ontrolled System#

Some embedded systems are predominantly interrupt controlled. This means that tas!s

performed by the system are triggered by different !inds of events. )n interrupt could be generated

10


11/125

for e8ample by a timer in a predefined freuency$ or by a serial port controller receiving a byte. These

!inds of systems are used if event handlers need low latency and the event handlers are short and

simple.

Csually these !inds of systems run a simple tas! in a main loop also$ but this tas! is not

very sensitive to une8pected delays. Sometimes the interrupt handler will add longer tas!s to a ueuestructure. %ater$ after the interrupt handler has finished$ these tas!s are e8ecuted by the main loop.

This method brings the system close to a multitas!ing !ernel with discrete processes.

&ooperative Multitas!ing#

) non-preemptive multitas!ing system is very similar to the simple control loop

scheme$ e8cept that the loop is hidden in an ),*. The programmer defines a series of tas!s$ and each

tas! gets its own environment to 2run3 in. Bhen a tas! is idle$ it calls an idle routine$ usually called

2pause3$ 2wait3$ 2yield3$ 2nop3 (stands for no operation$ etc. The advantages and disadvantages are

very similar to the control loop$ e8cept that adding new software is easier$ by simply writing a new

tas!$ or adding to the ueue-interpreter.

,rimitive Multitas!ing#

*n this type of system$ a low-level piece of code switches between tas!s or threads

based on a timer (connected to an interrupt. This is the level at which the system is generally

considered to have an ;operating system; !ernel. Depending on how much functionality is reuired$ it

introduces more or less of the comple8ities of managing multiple tas!s running conceptually in

parallel.

)s any code can potentially damage the data of another tas! (e8cept in larger systems

using an MMC programs must be carefully designed and tested$ and access to shared data must be

controlled by some synchroni9ation strategy$ such as message ueues$ semaphores or a non-bloc!ing

synchroni9ation scheme.

:ecause of these comple8ities$ it is common for organi9ations to buy a real-time

operating system$ allowing the application programmers to concentrate on device functionality rather

than operating system services$ at least for large systemsJ smaller systems often cannot afford the

overhead associated with a generic real time system$ due to limitations regarding memory si9e$

performance$ andor battery life.

11


12/125


13/125

Eg# &onsider a TK remote control system$ if the remote control ta!es a few milliseconds delay it will

not cause damage either to the TK or to the remote control. These systems which will not cause damage when

they are not operated at considerable time period those systems comes under soft real-time embedded systems.

(.*.1 Network comm$nication emedded s/stems"

) wide range networ! interfacing communication is provided by using embedded

systems.

Eg#

&onsider a web camera that is connected to the computer with internet can be used to

spread communication li!e sending pictures$ images$ videos etc..$ to another computer

with internet connection throughout anywhere in the world.

&onsider a web camera that is connected at the door loc!.

Bhenever a person comes near the door$ it captures the image of a person and sends to

the des!top of your computer which is connected to internet. This gives an alerting message with

image on to the des!top of your computer$ and then you can open the door loc! just by clic!ing the

mouse. 5ig# . show the networ! communications in embedded systems.

;ig (.(" Network comm$nication emedded s/stems

13


14/125

(.*.4 Different t/&es of &rocessing $nits"

The central processing unit (c.p.u can be any one of the following microprocessor$

microcontroller$ digital signal processing.

)mong these Microcontroller is of low cost processor and one of the main advantage of

microcontrollers is$ the components such as memory$ serial communication interfaces$ analog

to digital converters etc..$ all these are built on a single chip. The numbers of e8ternal

components that are connected to it are very less according to the application.

Microprocessors are more powerful than microcontrollers. They are used in major applications

with a number of tas!ing reuirements. :ut the microprocessor reuires many e8ternal

components li!e memory$ serial communication$ hard dis!$ input output ports etc..$ so the

power consumption is also very high when compared to microcontrollers.

Digital signal processing is used mainly for the applications that particularly involved with

processing of signals

(.1 APP3ICATIONS O; E+,EDDED S-STE+S"

(.1.! Cons$mer a&&lications"

)t home we use a number of embedded systems which include microwave oven$

remote control$ vcd players$ dvd players$ camera etcL.

;ig(.*" A$tomatic coffee makes e@$i&ment

14


15/125

(.1.( Office a$tomation"

Be use systems li!e fa8 machine$ modem$ printer etcL

;ig(.1" ;a0 mac%ine ;ig(.4" Printing mac%ine

(.1.*. Ind$strial a$tomation"

Today a lot of industries are using embedded systems for process control. *n industries

we design the embedded systems to perform a specific operation li!e monitoring temperature$

pressure$ humidity $voltage$ current etc..$ and basing on these monitored levels we do control other

devices$ we can send information to a centrali9ed monitoring station.

;ig(.5" oot

*n critical industries where human presence is avoided there we can use robotswhich

are programmed to do a specific operation.

15


16/125

(.1.4 Com&$ter networking"

Embedded systems are used as bridges routers etc..

;ig(.6" Com&$ter networking

(.1.5 Tele comm$nications"

&ell phones$ web cameras etc.

;ig(.8" Cell P%one ;ig(.9" 2e camera

CHAPTE *" HAD2AE DESCIPTION"16


17/125

*.! Introd$ction#

*n this chapter the bloc! diagram of the project and design aspect of independent

modules are considered. :loc! diagram is shown in fig# .+#

;I7 *.!" ,lock diagram of 7S+ OPEATION DI7ITA3 ENE7- +ETE

T%e main locks of t%is &ro'ect are#+. Micro controller (+45677)

. 'eset button

. &rystal oscillator

/. 'egulated power supply (',S

17


18/125

1. %ed indicator

4. Energy meter

7. =ptocoupler

6. "SM modem

?. 'elay

+@. %&D

++. Tamper switch

*.( +icro controller"

+icro controller"

;ig" *.( +icrocontrollers

*.(.! Introd$ction to +icrocontrollers"

&ircumstances that we find ourselves in today in the field of microcontrollers had their

beginnings in the development of technology of integrated circuits. This development has made it

possible to store hundreds of thousands of transistors into one chip. That was a prereuisite for

production of microprocessors$ and the first computers were made by adding e8ternal peripherals such

as memory$ input-output lines$ timers and other. 5urther increasing of the volume of the pac!age

resulted in creation of integrated circuits. These integrated circuits contained both processor and

peripherals. That is how the first chip containing a microcomputer$ or what would later be !nown as a

microcontroller came about.

18


19/125

Microprocessors and microcontrollers are widely used in embedded systems products.

Microcontroller is a programmable device. ) microcontroller has a &,C in addition to a fi8ed amount

of ')M$ '=M$ *= ports and a timer embedded all on a single chip. The fi8ed amount of on-chip

'=M$ ')M and number of *= ports in microcontrollers ma!es them ideal for many applications in

which cost and space are critical.

The microcontroller used in this project is ,*&+45677). The ,*& families of

microcontrollers are developed by Microchip Technology *nc. &urrently they are some of the most

popular microcontrollers$ selling over +@ million devices each year. There are basically four families

of ,*& microcontrollers#

,*&+& ++/-bit program word

,*& +4&1 +-bit program word

,*&+4& and ,*&+45 +/-bit program word

,*&+7& and ,*&+6& +4-bit program word

The features$ pin description of the microcontroller used are discussed in the following sections.

*.(.( Descri&tion"

*ntroduction to PIC Microcontrollers:

,*& stands for ,eripheral *nterface &ontroller given by Microchip Technology toidentify its single-chip microcontrollers. These devices have been very successful in 6-bit

microcontrollers. The main reason is that Microchip Technology has continuously upgraded the

device architecture and added needed peripherals to the microcontroller to suit customersigh range crystal

20


21/125

'& oscillator (low cost.

1. ,rogrammable timers and on-chip )D&.

4. Cp to + independent interrupt sources.

7. ,owerful output pin control (1 m) (ma8. current sourcing capability per pin.

6. E,'=M=T,'=M5lash memory option.

?. *= port e8pansion capability.

CP# Architectre:

The &,C uses >arvard architecture with separate ,rogram and Kariable (data memory interface.

This facilitates instruction fetch and the operation on dataaccessing of variables simultaneously.)rchitecture of ,*& microcontroller

;ig.*.*.Arc%itect$re of PIC microcontroller

:asically$ all ,*& microcontrollers offer the following features#

'*S& instruction set with around 1 instructions O? Digital *= ports

=n-chip timer with 6-bit prescaler.

,ower-on reset

Batchdog timer

,ower saving S%EE, mode

Direct$ indirect$ and relative addressing modes

E8ternal cloc! interface

')M data memory

E,'=M (or =T, program memory

21


22/125

,eripheral features"

>igh sin!source current 1m)

Timer@# 6-bit timercounter with 6-bit prescaler can be incremented during sleep via e8ternal

crystalcloc!

Timer#6-bit timercounter with 6-bit period register prescaler and post scalar.

&apture$ &ompare$ ,BM (&&, module

&apture is +4-bit$ ma8 resolution is +.1ns

&ompare is +4-bit$ ma8 resolution is @@ ns

,BM ma8$ resolution is +@-bit

6-bit 1 channel analog-to-digital converter

Synchronous serial port (SS, with S,* (MasterSlave and (Slave

Some devices offer the following additional features#

)nalogue input channels

)nalogue comparators

)dditional timer circuits

EE,'=M data memory

5lash EE,'=M program memory

E8ternal and timer interrupts

*n-circuit programming

*nternal oscillator

CS)'T serial interface

*.(.* Pin diagram"

22


23/125

;ig.*.1.PIN DIA7A+ O; PIC!5;866

,ic+4f677 is a /@ pin microcontroller. *t has 1 ports port )$ port :$ port &$ port D$ port E. )ll the pins

of the ports are for interfacing input output devices.

,ort )# *t consists of 4 pins from )@ to )1

,ort :# *t consists of 6 pins from :@ to :7

,ort *t consists of 6 pins from &@ to &7

,ort D# *t consists of 6 pins from D@ to D7

,ort E# *t consists of pins from E@ to E

The rest of the pins are mandatory pins these should not be used to connect inputoutput devices.

,in + is M&%' (master clear pin pin also referred as reset pin.

23


24/125

,in +$ +/ are used for crystal oscillator to connect to generate a freuency of about @M>9.

,in ++$ + and+$ are used for voltage supply Kdd(Pand Kss(-

,*& +45677) Specification#

')M 46 bytes

EE,'=M 14 bytes

5lash ,rogram Memory 6! words

=perating 5reuency D& to @M>9

*= port ,ort )$:$&$D$E

This is the specification for ,*&+45677) from Microchip. ) single microcontroller

which is very brilliant and useful. )lso this microcontroller is very easy to be assembled$ program and

also the price is very cheap. *t cost less than +@ dollar. The good thing is that single unit can be

purchased at that +@ dollar price. Cnli!e some other *ntegrated &ircuit that must be bought at a

minimum order uantity such as +@@@ units or @@@ units or else you wonQt be able to purchase it.

=ne unit of ,*&+45677) microcontroller can be programmed and erased so many times.

Some said about +@ @@@ times. *f you are doing programming and downloading your code into the

,*& @ times a day that means you can do that for 1@@ days which is more than a yearR

The erasing time is almost unnoticeable because once new program are loaded into the ,*&$

the old program will automatically be erased immediately. During my time of Degree study$ * did not

use ,*& but * use other type of microcontroller. * have to wait for about +1 to @ minutes to erase the

EE,'=M before * can load a new program and test the microcontroller. =ne day * can only modify

my code and test it for less than +@ times. +@8+1 minutes N +1@ minutes.

A+"

24


25/125

,*&+45677) already made with 46 bytes of 'andom )ccess Memory (')M inside it. )ny

temporary variable storage that we wrote in our program will be stored inside the ')M. Csing this

microcontroller you donQt need to buy any e8ternal ')M.

EEPO+"

14 bytes of EE,'=M are available also inside this microcontroller. This is very useful to

store information such as ,*0 0umber$ Serial 0umber and so on. Csing EE,'=M is very important

because data stored inside EE,'=M will be retained when power supply is turn off. ')M did not

store data permanently. Data inside ')M is not retained when power supply is turn off.

The si9e of program code that can be stored is about 6! words inside ,*&+45677) '=M. +

word si9e is +/ bits. :y using the free version of the &&S & compiler only ! words of program can

be written and compiled. To write 6! words of & program you have to purchase the original &&S &

compiler and it cost less than 7@@ dollar.

Cr/stal oscillator#

The crystal oscillator speed that can be connected to the ,*& microcontroller range from D& to

@Mh9. Csing the &&S & compiler normally @Mh9 oscillator will be used and the price is very

cheap. The @ M>9 crystal oscillator should be connected with about p5 capacitor. ,lease refer to

my circuit schematic.

There are 1 inputoutput ports on ,*& microcontroller namely port )$ port :$ port &$ port D

and port E. Each port has different function. Most of them can be used as *= port.

*.* E7#3ATED PO2E S#PP3-"

*.*.! Introd$ction"

,ower supplyis a supply ofelectrical power. ) device or system that supplies electrical

or other types ofenergy to an outputload or group of loads is called apower supply unitor,SC. The

term is most commonly applied to electrical energy supplies$ less often to mechanical ones$ and rarely

to others.

25


26/125

) power supply may include a power distribution system as well as primary or

secondary sources of energy such as

&onversion of one form of electrical power to another desired form and voltage$ typically

involving converting)& line voltage to a well-regulated lower-voltageD& for electronic devices.

%ow voltage$ low power D& power supply units are commonly integrated with the devices they

supply$ such ascomputersand household electronics.

:atteries.

&hemicalfuel cells and other forms ofenergy storagesystems.

Solar power.

"enerators oralternators.

*.*.( ,lock Diagram"

;ig *.*.( eg$lated Power S$&&l/

26


27/125

The basic circuit diagram of a regulated power supply (D& =, with led connected as

load is shown in fig# ...

;ig *.*.* Circ$it diagram of eg$lated Power S$&&l/ wit% 3ed connection

The components mainly used in above figure are

@K )& M)*0S

T')0S5='ME'

:'*D"E 'E&T*5*E'(D*=DES

&),)&*T='

K=%T)"E 'E"C%)T='(*& 76@1

'ES*ST='

%ED(%*">T EM*TT*0" D*=DE

The detailed e8planation of each and every component mentioned above is as follows#

Transformation" The process of transforming energy from one device to another is called

transformation. 5or transforming energy we use transformers.

Transformers"

27


28/125

) transformer is a device that transfers electrical energy from one circuit to another

through inductively coupled conductors without changing its freuency. ) varying current in the first

or primary winding creates a varying magnetic flu8 in the transformer9 )& mains supply$ this will happen 1@ times a second. This is called

MCTC)% *0DC&T*=0 and forms the basis of the transformer.

The input coil is called the ,'*M)' B*0D*0"J the output coil is the

SE&=0D)' B*0D*0". 5ig# ../ shows step-down transformer.

;ig *.*.1" Ste&?Down Transformer

The voltage induced in the secondary is determined by the TC'0S ')T*=.

28


29/125

5or e8ample$ if the secondary has half the primary turnsJ the secondary will have half

the primary voltage.

)nother e8ample is if the primary has 1@@@ turns and the secondary has 1@@ turns$ then

the turnQs ratio is +@#+.

*f the primary voltage is /@ volts then the secondary voltage will be 8 +@ smaller N /

volts. )ssuming a perfect transformer$ the power provided by the primary must eual the power ta!en

by a load on the secondary. *f a /-watt lamp is connected across a / volt secondary$ then the

primary must supply / watts.

To aid magnetic coupling between primary and secondary$ the coils are wound on a

metal &='E. Since the primary would induce power$ called EDD &C''E0TS$ into this core$ the

core is %)M*0)TED. This means that it is made up from metal sheets insulated from each other.

Transformers to wor! at higher freuencies have an iron dust core or no core at all.

0ote that the transformer only wor!s on )&$ which has a constantly changing current

and moving field. D& has a steady current and therefore a steady field and there would be no

induction.

Some transformers have an electrostatic screen between primary and secondary. This is

to prevent some types of interference being fed from the euipment down into the mains supply$ or in

the other direction. Transformers are sometimes used for *M,ED)0&E M)T&>*0".

Be can use the transformers as step up or step down.

Ste& #& transformer"

*n case of step up transformer$ primary windings are every less compared to secondary

winding.

:ecause of having more turns secondary winding accepts more energy$ and it releases

more voltage at the output side.

Ste& down transformer"

29


30/125

*ncase of step down transformer$ ,rimary winding induces more flu8 than the

secondary winding$ and secondary winding is having less number of turns because of that it accepts

less number of flu8$ and releases less amount of voltage.

,atter/ &ower s$&&l/"

)batteryis a type of linear power supply that offers benefits that traditional line-

operated power supplies lac!# mobility$ portability and reliability. ) battery consists of multiple

electrochemical cells connected to provide the voltage desired. 5ig# ..1 shows >i-Batt ?K battery

;ig *.*.4" Hi?2att 9> ,atter/

The most commonly used dry-cellbattery is thecarbon-9inc dry cell battery. Dry-cell

batteries are made by stac!ing a carbon plate$ a layer of electrolyte paste$ and a 9inc plate alternately

until the desired total voltage is achieved. The most common dry-cell batteries have one of the

following voltages# +.1$ $ 4$ ?$ .1$ /1$ and ?@. During the discharge of a carbon-9inc battery$ the

9inc metal is converted to a 9inc salt in the electrolyte$ and magnesium dio8ide is reduced at the

carbon electrode. These actions establish a voltage of appro8imately +.1 K.

The lead-acidstorage battery may be used. This battery is rechargeableJ it consists of

lead and leaddio8ide electrodes which are immersed in sulfuric acid. Bhen fully charged$ this type of

battery has a .@4-.+/ K potential () + voltcar batteryuses 4 cells in series. During discharge$ the

lead is converted to lead sulfate and the sulfuric acid is converted to water. Bhen the battery is

charging$ the lead sulfate is converted bac! to lead and lead dio8ide ) nic!el-cadmiumbattery has

become more popular in recent years. This battery cell is completely sealed and rechargeable. The

electrolyte is not involved in the electrode reaction$ ma!ing the voltage constant over the span of the

batteries long service life. During the charging process$ nic!el o8ide is o8idi9ed to its higher o8idation

state and cadmium o8ide is reduced. The nic!el-cadmium batteries have many benefits. They can be

30
http://en.wikipedia.org/wiki/Battery_(electricity)http://en.wikipedia.org/wiki/Dry-cellhttp://en.wikipedia.org/wiki/Carbon-zinchttp://en.wikipedia.org/wiki/Lead-acidhttp://en.wikipedia.org/wiki/Car_batteryhttp://en.wikipedia.org/wiki/Nickel-cadmiumhttp://en.wikipedia.org/wiki/Battery_(electricity)http://en.wikipedia.org/wiki/Dry-cellhttp://en.wikipedia.org/wiki/Carbon-zinchttp://en.wikipedia.org/wiki/Lead-acidhttp://en.wikipedia.org/wiki/Car_batteryhttp://en.wikipedia.org/wiki/Nickel-cadmium


31/125

stored both charged and uncharged. They have a long service life$ high current availabilities$ constant

voltage$ and the ability to be recharged. 5ig# ..4 shows pencil battery of +.1K.

;ig *.*.5" Pencil ,atter/ of !.4>

ectification"

The process of converting an alternating current to a pulsating direct current is called

as rectification. 5or rectification purpose we use rectifiers.

ectifiers"

) rectifier is an electrical device that converts alternating current ()& to direct current

(D&$ a process !nown as rectification. 'ectifiers have many uses including as components of power

supplies and as detectors of radio signals. 'ectifiers may be made of solid-state diodes$ vacuum tube

diodes$ mercury arc valves$ and other components.

) device that it can perform the opposite function (converting D& to )& is !nown as

an inverter.

Bhen only one diode is used to rectify )& (by bloc!ing the negative or positive

portion of the waveform$ the difference between the term diode and the term rectifier is merely one

of usage$ i.e.$ the term rectifier describes a diode that is being used to convert )& to D&. )lmost all

rectifiers comprise a number of diodes in a specific arrangement for more efficiently converting )& to

D& than is possible with only one diode. :efore the development of silicon semiconductor rectifiers$

vacuum tube diodes and copper (* o8ide or selenium rectifier stac!s were used.

,ridge f$ll wa)e rectifier"

31


32/125

The :ridge rectifier circuit is shown in fig# ..7$ which converts an ac voltage to dc

voltage using both half cycles of the input ac voltage. The :ridge rectifier circuit is shown in the

figure. The circuit has four diodes connected to form a bridge. The ac input voltage is applied to the

diagonally opposite ends of the bridge. The load resistance is connected between the other two ends of

the bridge.

5or the positive half cycle of the input ac voltage$ diodes D+ and D conduct$ whereas

diodes D and D/ remain in the =55 state. The conducting diodes will be in series with the load

resistance '%and hence the load current flows through '%.

5or the negative half cycle of the input ac voltage$ diodes D and D/ conduct

whereas$ D+ and D remain =55. The conducting diodes D and D/ will be in series with the load

resistance '%and hence the current flows through '%in the same direction as in the previous half

cycle. Thus a bi-directional wave is converted into a unidirectional wave.

*nput =utput

;ig *.*.6" ,ridge rectifier" a f$ll?wa)e rectifier $sing 1 diodes

D,!:6"

0ow -a -days :ridge rectifier is available in *& with a number of D:+@7. *n our project

we are using an *& in place of bridge rectifier. The picture of D: +@7 is shown in fig# ..6.

;eat$res"

32


33/125

"ood for automation insertion

Surge overload rating - @ amperes pea!

*deal for printed circuit board

'eliable low cost construction utili9ing molded

"lass passivated device

,olarity symbols molded on body

Mounting position# )ny

Beight# +.@ gram

;ig *.*.8" D,!:6

;iltration"

The process of converting a pulsating direct current to a pure direct current using filters

is called as filtration.

;ilters"

Electronic filters are electronic circuits$ which perform signal-processing functions$

specifically to remove unwanted freuency components from the signal$ to enhance wanted ones.

Introd$ction to Ca&acitors"

33


34/125

The &apacitor or sometimes referred to as a &ondenser is a passive device$ and one

which stores energy in the form of an electrostatic field which produces a potential (static voltage

across its plates. *n its basic form a capacitor consists of two parallel conductive plates that are not

connected but are electrically separated either by air or by an insulating material called the Dielectric.

Bhen a voltage is applied to these plates$ a current flows charging up the plates with electrons giving

one plate a positive charge and the other plate an eual and opposite negative charge This flow of

electrons to the plates is !nown as the &harging &urrent and continues to flow until the voltage across

the plates (and hence the capacitor is eual to the applied voltage Kcc. )t this point the capacitor is

said to be fully charged and this is illustrated below. The construction of capacitor and an electrolytic

capacitor are shown in figures ..? and ..+@ respectively.

;ig *.*.9"Constr$ction Of a Ca&acitor ;ig *.*.!:"Electrol/tic Ca&aticor

Cnits of &apacitance#

Microfarad (5 +5 N ++$@@@$@@@ N @.@@@@@+ N +@-45

0anofarad (n5 +n5 N ++$@@@$@@@$@@@ N @.@@@@@@@@+ N +@-?

5

,ico farad (p5 +p5 N ++$@@@$@@@$@@@$@@@ N @.@@@@@@@@@@@+ N +@-+5

O&eration of Ca&acitor"

34


35/125

Thin! of water flowing through a pipe. *f we imagine a capacitor as being a storage

tan! with an inlet and an outlet pipe$ it is possible to show appro8imately how an electronic capacitor

wor!s.

5irst$ letowever$ if there is a steady current$ only the initial short burst

will flow until the ;floating ball valve; closes and stops further

flow.

So a coupling capacitor allows ;alternating current; to pass through because the ball

valve doesnowever$ a steady current uic!ly

fills the tan! so that all flow stops.

) capacitor will pass alternating current but (apart from an initial surge it will not pass

d.c.

Bhere a capacitor is used to decouple a circuit$ the effect is to

;smooth out ripples;. )ny ripples$ waves or pulses of current are

passed to ground while d.c. 5lows smoothly.

35


36/125

eg$lation"

The process of converting a varying voltage to a constant regulated voltage is called as

regulation. 5or the process of regulation we use voltage regulators.

>oltage eg$lator"

) voltage regulator (also called a UregulatorQ with only three terminals appears to be a

simple device$ but it is in fact a very comple8 integrated circuit. *t converts a varying input voltage

into a constant UregulatedQ output voltage. Koltage 'egulators are available in a variety of outputs li!e

1K$ 4K$ ?K$ +K and +1K. The %M76 series of voltage regulators are designed for positive input.

5or applications reuiring negative input$ the %M7? series is used. Csing a pair of Uvoltage-

dividerQ resistors can increase the output voltage of a regulator circuit.

*t is not possible to obtain a voltage lower than the stated rating. ou cannot use a +K

regulator to ma!e a 1K power supply. Koltage regulators are very robust. These can withstand over-

current draw due to short circuits and also over-heating. *n both cases$ the regulator will cut off before

any damage occurs. The only way to destroy a regulator is to apply reverse voltage to its input.

'everse polarity destroys the regulator almost instantly. 5ig# ..++ shows voltage regulator.

;ig *.*.!!" >oltage eg$lator

36


37/125

esistors"

) resistor is a two-terminal electronic component that produces a voltage across its terminals

that is proportional to the electric current passing through it in accordance with =hm


38/125

;ig *.*.!(" esistor ;ig *.*.!*" Color ,ands In esistor

*.1. 3ED"

) light-emitting diode (%ED is a semiconductor light source. %EDQs are used as

indicator lamps in many devices$ and are increasingly used for lighting. *ntroduced as a practical

electronic component in +?4$ early %EDQs emitted low-intensity red light$ but modern versions are

available across the visible$ ultraviolet and infrared wavelengths$ with very high brightness. The

internal structure and parts of a led are shown in figures ./.+ and ./. respectively.

38


39/125

;ig *.1.!" Inside a 3ED ;ig *.1.(" Parts of a 3ED

2orking"

The structure of the %ED light is completely different than that of the light bulb.

)ma9ingly$ the %ED has a simple and strong structure. The light-emitting semiconductor material is

what determines the %EDowever$ they are relatively e8pensive and reuire more precise current and

heat management than traditional light sources. &urrent %ED products for general lighting are more

e8pensive to buy than fluorescent lamp sources of comparable output. They also enjoy use in

applications as diverse as replacements for traditional light sources in automotive lighting

(particularly indicators and in traffic signals. The compact si9e of %EDQs has allowed new te8t and

video displays and sensors to be developed$ while their high switching rates are useful in advanced

communications technology. The electrical symbol and polarities of led are shown in fig# ./..

;ig *.1.*" Electrical S/mol B Polarities of 3ED

39


40/125

%ED lights have a variety of advantages over other light sources#

>igh-levels of brightness and intensity

>igh-efficiency

%ow-voltage and current reuirements

%ow radiated heat

>igh reliability (resistant to shoc! and vibration

0o CK 'ays

%ong source life

&an be easily controlled and programmed

)pplications of %ED fall into three major categories#

Kisual signal application where the light goes more or less directly from the %ED to the human

eye$ to convey a message or meaning.

*llumination where %ED light is reflected from object to give visual response of these objects.

"enerate light for measuring and interacting with processes that do not involve the human

visual system.

*.4 ENE7- +ETE"

)n electric meteror energ/ meteris a device that measures the amount of electricalenergy

consumed by a residence$business$ or an electrically-powered device.

Electric meters are typically calibrated in billing units$ the most common one being the !ilowatt hour.

,eriodic readings of electric meters establish billing cycles and energy used during a cycle.

*n settings when energy savings during certain periods are desired$ meters may measure demand$ the

ma8imum use of power in some interval. *n some areas$ the electric rates are higher during certain

40
http://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Househttp://en.wikipedia.org/wiki/Businesshttp://en.wikipedia.org/wiki/Kilowatt_hourhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Househttp://en.wikipedia.org/wiki/Businesshttp://en.wikipedia.org/wiki/Kilowatt_hour


41/125

times of day$ to encourage reduction in use. )lso$ in some areas meters have relays to turn off

nonessential euipment

*.4.! T%eor/"

The first accurate$ recording electricity consumption meter was a D&meter by Dr >ermann )ron$

who patented it in +66. >ugo >irstof the"eneral Electric &ompanyintroduced it commercially into

"reat :ritain from +666.GHMeters had been used prior to this$ but they measured the rate of power

consumption at that particular moment. )ron


42/125

Cnit of measurement

,anel-mounted solid state electricity meter$ connected to a MK)electricity substation.'emote

current and voltage sensors can be read and programmed remotely by modemand locally by infra-red.

The circle with two dots is the infra-red port. Tamper-evident seals can be seen.

The most common unit of measurement on the electricity meter is the !ilowatt hour$ which is eual to

the amount of energy used by a load of one !ilowattover a period of one hour$ or $4@@$@@@joules.

Some electricity companies use the S*mega jouleinstead.

Demand is normally measured in watts$ but averaged over a period$ most often a uarter or half hour.

'eactive poweris measured in ;Kolt-amperes reactive;$ (varh in !ilovar-hours. :y convention$ a

;lagging; or inductiveload$ such as a motor$ will have positive reactive power. ) ;leading;$ or

capacitiveload$ will have negative reactive power.G/H

Kolt-amperes measures all power passed through a distribution networ!$ including reactive and actual.

This is eual to the product of root-mean-suare volts and amperes.

Distortion of the electric current by loads is measured in several ways. ,ower factoris the ratio of

resistive (or real power to volt-amperes. ) capacitive load has a leading power factor$ and an

inductive load has a lagging power factor. ) purely resistive load (such as a filament lamp$ heater or

!ettle e8hibits a power factor of +. &urrent harmonics are a measure of distortion of the wave form.

42
http://en.wikipedia.org/wiki/Solid_state_(electronics)http://en.wikipedia.org/wiki/Apparent_powerhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Infra-redhttp://en.wikipedia.org/wiki/Kilowatt_hourhttp://en.wikipedia.org/wiki/Kilowatthttp://en.wikipedia.org/wiki/Hourhttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/Megajoulehttp://en.wikipedia.org/wiki/Reactive_powerhttp://en.wikipedia.org/wiki/Volt-amperes_reactivehttp://en.wikipedia.org/wiki/Inductancehttp://en.wikipedia.org/wiki/Capacitivehttp://en.wikipedia.org/wiki/Electricity_meter#cite_note-3http://en.wikipedia.org/wiki/Electricity_meter#cite_note-3http://en.wikipedia.org/wiki/Power_factorhttp://en.wikipedia.org/wiki/File:CommercialElectricityMeter.jpghttp://en.wikipedia.org/wiki/File:CommercialElectricityMeter.jpghttp://en.wikipedia.org/wiki/Solid_state_(electronics)http://en.wikipedia.org/wiki/Apparent_powerhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Infra-redhttp://en.wikipedia.org/wiki/Kilowatt_hourhttp://en.wikipedia.org/wiki/Kilowatthttp://en.wikipedia.org/wiki/Hourhttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/Megajoulehttp://en.wikipedia.org/wiki/Reactive_powerhttp://en.wikipedia.org/wiki/Volt-amperes_reactivehttp://en.wikipedia.org/wiki/Inductancehttp://en.wikipedia.org/wiki/Capacitivehttp://en.wikipedia.org/wiki/Electricity_meter#cite_note-3http://en.wikipedia.org/wiki/Power_factor


43/125

5or e8ample$ electronic loads such as computer power supplies draw their current at the voltage pea!

to fill their internal storage elements. This can lead to a significant voltage drop near the supply

voltage pea! which shows as a flattening of the voltage waveform. This flattening causes odd

harmonics which are not permissible if they e8ceed specific limits$ as they are not only wasteful$ but

may interfere with the operation of other euipment. >armonic emissions are mandated by law in EC

and other countries to fall within specified limits.

=ther units of measurement

*n addition to metering based on the amount of energy used$ other types of metering are available.

Meters which measured the amount of charge (coulombs used$ !nown as ampere-hour meters$ were

used in the early days of electrification. These were dependent upon the supply voltage remaining

constant for accurate measurement of energy usage$ which was not a li!ely circumstance with most

supplies.

Some meters measured only the length of time for which charge flowed$ with no measurement of the

magnitude of voltage or current is made. These were only suited for constant-load applications.

0either type is li!ely to be used today.

*.4.( T/&es of energ/ meters"

!. Electromec%anical ind$ction meter

43
http://en.wikipedia.org/wiki/Coulombhttp://en.wikipedia.org/wiki/Ampere-hourhttp://en.wikipedia.org/wiki/File:ElectricityMeterMechanism.jpghttp://en.wikipedia.org/wiki/File:ElectricityMeterMechanism.jpghttp://en.wikipedia.org/wiki/Coulombhttp://en.wikipedia.org/wiki/Ampere-hour


44/125

Mechanism of electromechanical inductionmeter# X - Koltage coil - many turns of fine wire encased

in plastic$ connected in parallel with load. X - &urrent coil - three turns of thic! wire$ connected in

series with load. X - Stator - concentrates and confines magnetic field. X - )luminum rotor disc. X -

rotor bra!e magnets. X - spindle with worm gear. X - display dials - note that the ++@$ +@ and +@@@

dials rotate cloc!wisewhile the +$ +@@ and +@@@@ dials rotate counter-cloc!wise.

Electricity meters operate by continuously measuring the instantaneous voltage(volts and current

(amperes and finding theproduct of these to give instantaneous electrical power (watts which is then

integratedagainst time to give energyused (joules$ !ilowatt-hours etc. Meters for smaller services

( such as small residential customers can be connected directly in-line between source and customer.

5or larger loads$ more than about @@ amps of load$ current transformersare used$ so that the meter

can be located other than in line with the service conductors. The meters fall into two basic categories$

electromechanical and electronic.

(. Electromec%anical meters

This mechanical electricity meter has every other dial rotating counter-cloc!wise.

The most common type of electricity meter is the Thomson or electromechanicalinduction watt-hour

meter$ invented by Elihu Thomson in +666.The electromechanicalinductionmeter operates by

counting the revolutions of an aluminumdisc which is made to rotate at a speed proportional to the

power. The number of revolutions is thus proportional to the energy usage. *t consumes a small

amount of power$ typically around watts.

The metallic disc is acted upon by two coils. =ne coil is connected in such a way that it produces a

magnetic flu8 in proportion to the voltageand the other produces a magnetic flu8 in proportion to the

current. The field of the voltage coil is delayed by ?@ degrees using a lag coil.G7HThis produces eddy

currentsin the disc and the effect is such that a forceis e8erted on the disc in proportion to the product

44
http://en.wikipedia.org/wiki/Electromechanicalhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Clockwisehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Amperehttp://en.wikipedia.org/wiki/Product_(mathematics)http://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Integralhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Jouleshttp://en.wikipedia.org/wiki/Current_transformerhttp://en.wikipedia.org/wiki/Clockwisehttp://en.wikipedia.org/wiki/Electromechanicalhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Elihu_Thomsonhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Induction_coilhttp://en.wikipedia.org/wiki/Magnetic_fluxhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Electricity_meter#cite_note-6http://en.wikipedia.org/wiki/Eddy_currenthttp://en.wikipedia.org/wiki/Eddy_currenthttp://en.wikipedia.org/wiki/Forcehttp://en.wikipedia.org/wiki/File:Mechanical_electricity_meter_1965_%281%29.jpghttp://en.wikipedia.org/wiki/File:Mechanical_electricity_meter_1965_%281%29.jpghttp://en.wikipedia.org/wiki/Electromechanicalhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Clockwisehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Amperehttp://en.wikipedia.org/wiki/Product_(mathematics)http://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Integralhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Jouleshttp://en.wikipedia.org/wiki/Current_transformerhttp://en.wikipedia.org/wiki/Clockwisehttp://en.wikipedia.org/wiki/Electromechanicalhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Elihu_Thomsonhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Induction_coilhttp://en.wikipedia.org/wiki/Magnetic_fluxhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Electricity_meter#cite_note-6http://en.wikipedia.org/wiki/Eddy_currenthttp://en.wikipedia.org/wiki/Eddy_currenthttp://en.wikipedia.org/wiki/Force


45/125

of the instantaneous current and voltage. )permanent magnete8erts an opposing force proportional to

the speed of rotation of the disc. The euilibrium between these two opposing forces results in the disc

rotating at a speedproportionalto the power being used. The disc drives a register mechanism which

integratesthe speed of the disc over time by counting revolutions$ much li!e theodometerin a car$ in

order to render a measurement of the total energy used over a period of time.

The type of meter described above is used on asingle-phase)& supply. Differentphase

configurations use additional voltage and current coils.

*. Single &%ase energ/ meter

Three-phase electromechanical induction meter$ metering +@@ ) @/@@ K supply. >ori9ontal

aluminum rotor disc is visible in center of meter

The aluminum disc is supported by a spindle which has aworm gear which drives the register. The

register is a series of dials which record the amount of energy used. The dials may be of the

cyclometer type$ an odometer-li!e display that is easy to read where for each dial a single digitis

shown through a window in the face of the meter$ or of the pointer type where a pointer indicates each

digit. Bith the dial pointer type$ adjacent pointers generally rotate in opposite directions due to the

gearing mechanism.

45
http://en.wikipedia.org/wiki/Permanent_magnethttp://en.wikipedia.org/wiki/Angular_velocityhttp://en.wikipedia.org/wiki/Proportionality_(mathematics)http://en.wikipedia.org/wiki/Integralhttp://en.wikipedia.org/wiki/Odometerhttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Gear#Worm_gearhttp://en.wikipedia.org/wiki/Numerical_digithttp://en.wikipedia.org/wiki/File:ThreePhaseElectricityMeter.jpghttp://en.wikipedia.org/wiki/File:ThreePhaseElectricityMeter.jpghttp://en.wikipedia.org/wiki/Permanent_magnethttp://en.wikipedia.org/wiki/Angular_velocityhttp://en.wikipedia.org/wiki/Proportionality_(mathematics)http://en.wikipedia.org/wiki/Integralhttp://en.wikipedia.org/wiki/Odometerhttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Gear#Worm_gearhttp://en.wikipedia.org/wiki/Numerical_digit


46/125

The amount of energy represented by one revolution of the disc is denoted by the symbol Khwhich is

given in units of watt-hours per revolution. The value 7. is commonly seen. Csing the value ofKh$

one can determine their power consumption at any given time by timing the disc with a stopwatch. *f

the time in seconds ta!en by the disc to complete one revolution is t$ then the power in watts is

. 5or e8ample$ ifKhN 7.$ as above$ and one revolution too! place in +/./

seconds$ the power is +6@@ watts. This method can be used to determine the power consumption of

household devices by switching them on one by one.

Most domestic electricity meters must be read manually$ whether by a representative of thepower

companyor by the customer. Bhere the customer reads the meter$ the reading may be supplied to the

power company by telephone$postor over the internet.The electricity company will normally reuire

a visit by a company representative at least annually in order to verify customer-supplied readings and

to ma!e a basic safety chec! of the meter.

*n an induction type meter$ creep is a phenomenon that can adversely affect accuracy$ that occurs

when the meter disc rotates continuously with potential applied and the load terminals open circuited.

) test for error due to creep is called a creep test.

Two standards govern meter accuracy$ )0S* &+.@for 0orth )merica and *E& 4@1.

1. Electronic meters

Electronic meters display the energy used on an %&Dor %ED display$ and can also transmit readings

to remote places. *n addition to measuring energy used$ electronic meters can also record other

parameters of the load and supply such as ma8imum demand$power factorand reactive power used

etc. They can also support time-of-day billing$ for e8ample$ recording the amount of energy used

during on-pea! and off-pea! hours.

46
http://en.wikipedia.org/wiki/Electricity_retailinghttp://en.wikipedia.org/wiki/Electricity_retailinghttp://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Mailhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/ANSI_C12.20http://en.wikipedia.org/wiki/LCDhttp://en.wikipedia.org/wiki/Power_factorhttp://en.wikipedia.org/wiki/Reactive_powerhttp://en.wikipedia.org/wiki/Electricity_retailinghttp://en.wikipedia.org/wiki/Electricity_retailinghttp://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Mailhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/ANSI_C12.20http://en.wikipedia.org/wiki/LCDhttp://en.wikipedia.org/wiki/Power_factorhttp://en.wikipedia.org/wiki/Reactive_power


47/125

Solid stateelectricity meter used in a home in the0etherlands.

Electronic meters now use %ow ,ower 'adio$ "SM$",'S$:luetooth$ *rD)$ as well as 'S-/61wired lin!. The meters can now store the entire usage profiles with time stamps and relay them at a

clic! of a button. The demand readings stored with the profiles accurately indicate the load

reuirements of the customer. This load profiledata is processed at the utilities for billing and

planning purposes.

)M' ()utomatic Meter 'eading and 'M' ('emote Meter 'eading describe various systems that

allow meters to be chec!ed without the need to send a meter reader out. )n electronic meter can

transmit its readings by telephone line or radio to a central billing office. )utomatic meter reading can

be done with "SM("lobal System for Mobile &ommunications modems$ one is attached to each

meter and the other is placed at the central utility office.

47
http://en.wikipedia.org/wiki/Solid_statehttp://en.wikipedia.org/wiki/Netherlandshttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/GPRShttp://en.wikipedia.org/wiki/Bluetoothhttp://en.wikipedia.org/wiki/IrDAhttp://en.wikipedia.org/wiki/RS-485http://en.wikipedia.org/wiki/Load_profilehttp://en.wikipedia.org/wiki/Automatic_Meter_Readinghttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/File:Solid-state-electricity-meter.jpghttp://en.wikipedia.org/wiki/File:Solid-state-electricity-meter.jpghttp://en.wikipedia.org/wiki/Solid_statehttp://en.wikipedia.org/wiki/Netherlandshttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/GPRShttp://en.wikipedia.org/wiki/Bluetoothhttp://en.wikipedia.org/wiki/IrDAhttp://en.wikipedia.org/wiki/RS-485http://en.wikipedia.org/wiki/Load_profilehttp://en.wikipedia.org/wiki/Automatic_Meter_Readinghttp://en.wikipedia.org/wiki/GSM


48/125

4. Solid?state design

:asic bloc! diagram of an electronic energy meter

)s in the bloc! diagram$ the meter has a power supply$ a metering engine$ ) processing and

communication engine (i.e. amicrocontroller$ and other add-on modules such as 'T&$ %&D display$

communication portsmodules and so on.

The metering engine is given the voltage and current inputs and has a voltage reference$ samplers and

uanti9es followed by an )D& section to yield the digiti9ed euivalents of all the inputs. These inputs

are then processed using a Digital Signal Processorto calculate the various metering parameters such

as powers$ energies etc.

The largest source of long-term errors in the meter is drift in the preamp$ followed by the precision of

the voltage reference. :oth of these vary with temperature as well$ and vary wildly because most

meters are outdoors. &haracteri9ing and compensating for these is a major part of meter design.

The processing and communication section has the responsibility of calculating the various derived

uantities from the digital values generated by the metering engine. This also has the responsibility of

communication using various protocols and interface with other addon modules connected as slaves to

it.

'T& and other add-on modules are attached as slaves to the processing and communication section

for various inputoutput functions. =n a modern meter most if not all of this will be implemented

48
http://en.wikipedia.org/wiki/Microcontrollerhttp://en.wikipedia.org/wiki/File:Block_Diagram.JPGhttp://en.wikipedia.org/wiki/File:Block_Diagram.JPGhttp://en.wikipedia.org/wiki/Microcontroller


49/125

inside the microprocessor$ such as the 'eal Time &loc! ('T&$ %&D controller$ temperature sensor$

memory and analog to digital converters.

5. +$lti&le tariff )ariale rate meters

Electricity retailersmay wish to charge customers different tariffs at different times of the day to

better reflect the costs of generation and transmission. Since it is not possible to store electricity

during a period of low demand for use during a period of high demand$ costs will vary significantly

depending on the time of day. %ow cost generation capacity (baseload such as coal can ta!e many

hours to start$ meaning a surplus in times of low demand$ whereas high cost but fle8ible generating

capacity (such as gas turbines must be !ept available to respond at a momentistorically$ these have

often been used in conjunction with electricalstorage heaters or hot water storage systems.

Multiple tariffs are made easier by time of use (T=C meters which incorporate or are connected to a

time switchand which have multiple registers.

Switching between the tariffs may happen via a radio-activated switch rather than a time switch to

prevent tampering with a sealed time switch to obtain cheaper electricity.

#nited ingdom

49
http://en.wikipedia.org/wiki/Electricity_retailinghttp://en.wikipedia.org/wiki/Storage_heaterhttp://en.wikipedia.org/wiki/Time_switchhttp://en.wikipedia.org/wiki/File:Economy_7_Meter_and_Teleswitcher.JPGhttp://en.wikipedia.org/wiki/Electricity_retailinghttp://en.wikipedia.org/wiki/Storage_heaterhttp://en.wikipedia.org/wiki/Time_switch


50/125

Economy 7 Meter and Tele switcher

'adio-activated switchingis common in the CY$ with a nightly data signal sent within the long wave

carrier of ::& 'adio /$ +?6 !>9. The time of off-pea! usage is between +.@am - 7.@am$ and this

is designed to power storage heatersand immersion heaters.*n the CY$ such tariffs are branded

Economy 7or Bhite Meter. The popularity of such tariffs has declined in recent years$ at least in the

domestic mar!et$ due to the (perceived or real deficiencies of storage heaters and the low cost of

natural gas.

Somemeters using Economy 7switch the entire electricity supply to the cheaper rate during the 7

hour night time period$ not just the storage heater circuit. The downside of this is that the daytime rate

will be a touch higher$ and standing charges may be a little higher too. 5or instance$ normal rate

electricity may be 7p per !Bh$ whereas Economy 7


51/125

!. In?%ome energ/ $se dis&la/s

) potentially powerful means to reduce household energy consumptionis to provide convenient real-

time feedbac! to users so they can change their energy using behavior. 'ecently$ low-cost energy

feedbac! displays have become available. ) study using a consumer-readable meter in 1@@ =ntario

homes byHydro Oneshowed an average 4.1Z drop in total electricity use when compared with a

similarly si9ed control group.Hydro Onesubseuently offered free power monitors to @$@@@

customers based on the success of the pilot.G+/H,rojects such as"oogle ,ower Meter$ ta!e information

from a smart meter and ma!e it more readily available to users to help encourage conservation.

(. Smart meters

Smart meters go a step further than simple )M' (automatic meter reading. They offer additional

functionality including a real-time or near real-time reads$power outagenotification$ and power

uality monitoring. They allow price setting agencies to introduce different prices for consumption

based on the time of day and the season.

These price differences can be used to reduce pea!s in demand (load shifting or pea! lopping$

reducing the need for additional power plants and in particular the higher polluting and costly to

operate natural gas powered pea!er plants. The feedbac! they provide to consumers has also been

shown to cut overall energy consumption.Gcitation neededH

)nother type of smart meter usesno intrusive load monitoringto automatically determine the number

and type of appliances in a residence$ how much energy each uses and when. This meter is used by

electric utilities to do surveys of energy use. *t eliminates the need to put timers on all of the

appliances in a house to determine how much energy each uses.

*. Pre&a/ment meters

51
http://en.wikipedia.org/wiki/Energy_conservationhttp://en.wikipedia.org/wiki/Hydro_Onehttp://en.wikipedia.org/wiki/Electricity_meter#cite_note-13http://en.wikipedia.org/wiki/Google_PowerMeterhttp://en.wikipedia.org/wiki/Automatic_meter_readinghttp://en.wikipedia.org/wiki/Power_outagehttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Nonintrusive_load_monitoringhttp://en.wikipedia.org/wiki/File:PrepaymentMeter.jpghttp://en.wikipedia.org/wiki/Energy_conservationhttp://en.wikipedia.org/wiki/Hydro_Onehttp://en.wikipedia.org/wiki/Electricity_meter#cite_note-13http://en.wikipedia.org/wiki/Google_PowerMeterhttp://en.wikipedia.org/wiki/Automatic_meter_readinghttp://en.wikipedia.org/wiki/Power_outagehttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Nonintrusive_load_monitoring


52/125

,repayment meter and magnetic stripeto!ens$ from a rented accommodation in the CY The button

labeled Adisplays information and statistics such as current tariff and remaining credit. The button

labeled ,activates a small amount of emergency credit should the customer run out

1. A &re&a/ment ke/

The standard business model of electricity retailing involves the electricity company billing the

customer for the amount of energy used in the previous month or uarter. *n some countries$ if the

retailer believes that the customer may not pay the bill$ a prepayment meter may be installed. This

reuires the customer to ma!e advance payment before electricity can be used. *f the available credit

is e8hausted then the supply of electricity is cut off by a relay.

*n the CY$ mechanical prepayment meters used to be common in rented accommodation.

Disadvantages of these included the need for regular visits to remove cash$and ris! of theft of the

cash in the meter.

Modern solid-state electricity meters$ in conjunction withsmart cards$ have removed these

disadvantages and such meters are commonly used for customers considered to be a poor credit ris!.

*n the CY$ one system is the ,ay ,ointnetwor!$ where rechargeable to!ens ([uantum cards for

natural gas$ or plastic ;!eys; for electricity can be loaded with whatever money the customer has

available.

'ecently smartcards are introduced as much reliable to!ens that allows two way data e8change

between meter and the utility.

*n South )fricaand0orthern *relandprepaid meters are recharged by entering a uniue$ encoded

twenty digit number using a !eypad. This ma!es the to!ens$ essentially a slip of paper$ very cheap to

produce.

)round the world$ e8periments are going on$ especially in developing countries$ to test pre-payment

systems. *n some cases$ prepayment meters have not been accepted by customers. There are various

52
http://en.wikipedia.org/wiki/Magnetic_stripehttp://en.wikipedia.org/wiki/Relayhttp://en.wikipedia.org/wiki/Cashhttp://en.wikipedia.org/wiki/Smart_cardhttp://en.wikipedia.org/wiki/Credit_riskhttp://en.wikipedia.org/wiki/PayPointhttp://en.wikipedia.org/wiki/South_Africahttp://en.wikipedia.org/wiki/Northern_Irelandhttp://en.wikipedia.org/wiki/File:London_electricity_keymeter_key.jpghttp://en.wikipedia.org/wiki/File:London_electricity_keymeter_key.jpghttp://en.wikipedia.org/wiki/File:PrepaymentMeter.jpghttp://en.wikipedia.org/wiki/Magnetic_stripehttp://en.wikipedia.org/wiki/Relayhttp://en.wikipedia.org/wiki/Cashhttp://en.wikipedia.org/wiki/Smart_cardhttp://en.wikipedia.org/wiki/Credit_riskhttp://en.wikipedia.org/wiki/PayPointhttp://en.wikipedia.org/wiki/South_Africahttp://en.wikipedia.org/wiki/Northern_Ireland


53/125

groups$ such as the Standard Transfer Specification (STS association$ which promote common

standards for prepayment metering systems across manufacturers. >owever in spite of these efforts

prepayment meter mar!et had not spread e8cept in South )frica.

*.5" OPTOCO#P3E"

)n optocoupler-isolated power supply is often the safest and most practical way to go when it comes

to performance and protection. >ereQs the basic on todayQs %EDphoto detector isolators and what you

need to !now to apply them to your system.

The junior system designer often places the systemQs power reuirements at the end of the list$ and

thus overloo!s the importance of an isolated$ versus non-isolated )&)&$ )&D&$ D&)&$ or D&D&

converter. True isolation (transformer at the input$ optoisolator in the supplyQs feedbac! control loops

virtually removes any direct conductive path between the power supplyQs input stage and its output

terminalsload. ThatQs especially important in the high-power density applications that are becoming

more the rule than the e8ception$ and for more demanding system reuirements

That often place power supplies in e8plosive or otherwise ha9ardous environments.

The use of an optocoupler also acts to brea! ground loops$ and this functionality is valuable in

eliminating common-mode noise$ especially for systems wor!ing at the higher operating voltages.

Bhen different power supplies in a system are tied together$ ground loop currents tend to be induced

due to slight differences in ground potential.

*n addition$ power supplies tend to see transient noise in euipment that switches between various

power states (todayQs optocouplers are able to withstand up to /@ !Kmicrosecond transient common-

mode voltage. Typical optocouplers for performing this so-called galvanic isolation functionFin

essence to connect intrinsically safe circuitry to circuits that pose a safety ris!Fcomprise an %ED$ a

photo detector$ and appropriate connecting circuitry in the supplyQs output-to-input feedbac! %oop.

*n general circuit operation$ the optocoupler$ driven by the supplyQs ,BM$ serves as the lin! to

maintain the supplyQs desired output voltage Bhen the output voltage deviates either due to line

andor load changes$ the supplyQs error amplifier attempts to compensate. *t compares its input with a

reference voltage$ and the error signal thus controls the output of the ,BM. *n turn$ the ,BM directs

the primary- side

53
http://en.wikipedia.org/w/index.php?title=Standard_Transfer_Specification&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Standard_Transfer_Specification&action=edit&redlink=1


54/125

,ower M=S5ETs via the optocoupler

T%e standards

'egulatory agencies such as C% in the Cnited States$ &E0E%E& in Europe$ &S) in &anada$ and T**S

in apan$ set the power level needed to ma!e circuitry intrinsically safe. *n essence$ the standards set

the reuirements for the galvanic isolation barrier between the 2safe3 circuitry and the outside world.

5or best results$ choose optocouplers with

)dditional reinforced insulation as suggested by *E& E0-4@7/7- 1-. 'einforced insulation ensures

protection from electric shoc! as well as provides a failsafe mode. 5ail-safe techniues terminate

system operation and leaves system processes and components in a secure state when a failure occurs.

The input-voltage level usually defines the insulation voltage rating$ which typically ranges from 1@@

volts for some telecom applications to 1@@ volts for universal line-voltage capability. The regulations

you need to !now about$ and the specs you should study$ include *E&4@?1@$ E011@$ and *E&

4+@@@. *E& 4+@@@ in particular covers electromagnetic compatibility (EM&$ and part

/ of that document (*E&4+@@@- /-/ covers fast transientburst Electrical 5ast Transient (E5T testing

discussed in part /./ addresses interference simulated in inductively loaded switches. *n this standard$

the modules will be subjected to the following test levels$ depending on the designed environment#

%evel + (Bell protectedJ %evel (,rotectedJ %evel (Typical *ndustrial EnvironmentJ and %evel /

(Severe *ndustrial Environment$ where test voltage pea!s at the power supply ports are @.1 !K (1!>9

repetition rate$ + !K (1!>9$ !K (1!>9$ and / !K (.1!>9$ respectively.

A&&lications"

54


55/125

&omputer terminals

System appliances$ measuring instruments

'egisters$ copiers$ automatic vending machines

Electric home appliances$ such as fan heaters$ etc

Signal transmission between circuits of different potentials and impedances

*.6 7S+

7loal S/stem for +oile Comm$nication 7S+

Definition"

"SM$ which stands for "lobal System for Mobile communications$ reigns (important as the

worldQs most widely used cell phone technology. &ell phones use a cell phone service carrierQs "SM

networ! by searching for cell phone towers in the nearby area. "lobal system for mobile

communication ("SM is a globally accepted standard for digital cellular communication.

"SM is the name of a standardi9ation group established in +?6 to create a

common European mobile telephone standard that would formulate specifications for a pan-European

mobile cellular radio system operating at ?@@ M>9. *t is estimated that many countries outside of

Europe will join the "SM partnership.

55


56/125

+ODE+ SPECI;ICATIONS"

The S*M@@ is a complete Tri-band "SM solution in a compact plug-in module.

5eaturing an industry-standard interface$ the S*M@@ delivers "SM",'S?@@+6@@+?@@Mh9

performance for voice$ SMS$ data and 5a8 in a small form factor and with low power consumption.

The leading features of S*M@@ ma!e it deal fir virtually unlimited application$ such as B%%

applications (5i8ed &ellular Terminal$ MM application$ handheld devices and much more.

+. Tri-band "SM",'S module with a si9e of /@88.61

. &ustomi9ed MM* and !eypad%&D support

. )n embedded powerful T&,*, protocol stac!

/. :ased upon mature and field proven platform$ bac!ed up by our support service$ from

definition to design and production.

56


57/125

7eneral ;eat$res"

Tri-band "SM",'S?@@+6@@+?@@Mh9

",'S multi-slot class +@

",'S mobile station class A:

&omplaint to "SM phase P

i. -class /(B \?@@M>9

ii. -class +(+B \+6@@+?@@M>9

Dimensions# /@88.61 mm

Beight# 6gm

7. &ontrol via )T commands

("SM @7.@7$ @7.@1 and S*M&=M enhanced )T commands

S*M application tool !it

supply voltage range .1LL./.1 v

%ow power consumption

0ormal operation temperature# -@ Q& to P11 U&

'estricted operation temperature # -@ Q& to -1 U& and P11 Q& to P7@ U&

storage temperature# -/@ U& to P6@ U&

S&ecifications for ;a0"

"roup and class +

S&ecifications for Data"

",'S class +@# ma8 61.4 !bps (downlin!

,:&&> support

coding schemes &s +$$$/

&SD upto +/./ !bps

CSSD

57


58/125

0on transperant mode

,,,-stac!

S&ecifications for S+S )ia 7S+F7PS"

,oint to point M= and MT

SMS cell broadcast

Te8t and ,DC mode

Com&atiilit/"

)t cellular command interface

S&ecifications for )oice"

+. Tricodec

->alf rate (>'

-5ull rate (5'

-Enhanced full rate (E5'

. >ands free operation

(Echo cancellation

Dri)ers"

Microsoft windows mobile '*% driver

MC driver

Interfaces"

*nterface to e8ternal S*M v +.6v

4@ pins board-to-board connector

58


59/125

Two analog audio interfaces

Yeypad interfaces

%&D interface

'T& bac!up

)T commands via serial interface

Dual-Serial interfaces

)ntenna connector and antenna pad

A&&ro)als"

5T)

%ocal type approval

&E

Need of 7S+"

The "SM study group aimed to provide the followings through the "SM#

*mproved spectrum efficiency.

*nternational roaming.

%ow-cost mobile sets and base stations (:S

>igh-uality speech

&ompatibility with *ntegrated Services Digital 0etwor! (*SD0 and other telephone company

services.

Support for new services.

7S+ G Arc%itect$re"

) "SM networ! consists of several functional entities whose functions and interfaces are

defined. The "SM networ! can be divided into following broad parts.

The Mobile Station (MS

The :ase Station Subsystem (:SS

59


60/125

The 0etwor! Switching Subsystem (0SS

The =peration Support Subsystem (=SS

5ollowing fig shows the simple architecture diagram of "SM 0etwor!.

5ig# "SM 0etwor!.

The added components of the "SM architecture include the functions of the databases and messaging

systems#

>ome %ocation 'egister (>%'

Kisitor %ocation 'egister (K%'

Euipment *dentity 'egister (E*'

)uthentication &enter ()u&

SMS Serving &enter (SMS S&

"ateway MS& ("MS&

60


61/125

&hargebac! &enter (&:&

Transcoder and )daptation Cnit (T')C

5ollowing fig shows the diagram of "SM 0etwor! along with added elements.

5ig# "SM 0etwor! along with added elements.

The MS and the :SS communicate across the Cm interface$ also !nown as the air interface or

radio lin!. The :SS communicates with the 0etwor! Service Switching center across the ) interface.

7S+ network areas"

*n a "SM networ!$ the following areas are defined#

Cell"&ell is the basic service area$ one :TS covers one cell. Each cell is given a &ell "lobal *dentity

(&"*$ a number that uniuely identifies the cell.

3ocation Area") group of cells form a %ocation )rea. This is the area that is paged when a

subscriber gets an incoming call. Each %ocation )rea is assigned a %ocation )rea *dentity (%)*. Each

%ocation )rea is served by one or more :S&s.

MS&K%' Service )rea# The area covered by one MS& is called the MS&K%' service area.

P3+N"The area covered by one networ! operator is called ,%M0. ) ,%M0 can contain one or

more MS&s.

61


62/125

T%e 7S+ networks &arts are e0&lained

gsm based energy meter doc

Documents