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distribution substations. However, this reference didn%t take the operation modes of

several transformers in a substation into account.

!& a result, combining distribution network load distribution with the

transformer operation mode is of feasibility and necessary. 'istribution network

load distribution strategy considering the economy of parallel transformers is put

forward in this paper. $t is emphasi#ed that the ob(ect of study are all double

winding transformer.

! distribution network load distribution model is proposed which takes

distribution network reliability, transformer economic operation and load balancing

as the ob(ect function. E)pected energy not supplied *EE&+, comprehensive

power loss of transformer and the ma)imum difference among the load factor are

regarded as the evaluation indicators of distribution network reliability, transformer

economic operation and load balancing, respectively.

1.2 LITERATURE SURVEY

• Haibo iu, heng)iong Mao, iming u, 'an Wang in their paper

/0arallel operation of electronic power transformer based on distributed

logic control1 proposed that an ac2dc hybrid parallel operation control

scheme of E0T based on distributed logic control is proposed in order to

eliminate circulation current and further improve redundancy performance in

this paper. The proposed ac2dc hybrid parallel operation control scheme

consists of a dc side current-sharing control scheme and an ac side current-

sharing control scheme. The reali#ation of current-sharing no matter in theac side or in the dc side is based upon instantaneous average current method.

'etailed computer simulations based on M!T!32&$M4$5 for the two

E0Ts parallel operation is conducted, and this parallel system is also

implemented in laboratory based on '&0 TM&67897:;7. &imulation results

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and e)perimental results show that the proposed control scheme has good

current-sharing performance under both steady-state and dynamic operation.

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9ig ;.; oss profile of a =>5?! Transformer

1.3.2 LOAD LOSS

!ssociated with the full load current flow in the transformer windings and

varies with the s"uare of the load current *$7A+.!long with it there is linear loss

which is due to the temperature rise in the windings.

9ig ;.7 inear oss of a =>5?! Transformer

These losses are directly proportional to the rating of the transformers that is

when the transformer rating increases these losses value will also increase.

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1.4 PROPOSED SYSTEM

$n the proposed system we are splitting the transformer rating i.e. we are

using two small transformers instead of a single high rated transformer. Then we

are sensing the load current and switching the transformer according to the load

re"uirement. 'uring the lighter load conditions both the transformers are not

employed instead we are using anyone transformer that is most suitable for the

load. &o the losses are minimi#ed and the efficiency, reliability of the transformers

are improved and thus improving the whole systems efficiency.

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CHAPTER 2

BLOCK DIAGRAM

Fig 2.1 Block diagram of the Load optimization by implementing

embedded system in parallel operated transformers

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The block diagram consists of Transformers, Aelays, Microcontroller

*0$;B9::=+, ' 'isplay, urrent &ensor and oad.

When we switch C the power supply the Microcontroller starts it

functions. $nitially the Transformer *T;+ is connected to the bus and driving the

load the urrent &ensor senses the load current and produces proportional voltage

to the current in the circuit and gives it to the Microcontroller. 'epending upon the

load current the Microcontroller switches the Transformers i.e. connects or

disconnect the Transformers to the bus using Aelays.

$f the load current is minimum the Microcontroller connects Transformer

*T;+ alone to the bus so that it get energi#es and drive the load. &uppose if the load

increases then the Microcontroller connects Transformer *T7+ to the bus along with

Transformer *T;+ so that both the Transformers get energi#es and drives the load.

$n addition to that the Microcontroller disconnects both the transformers from the

bus and the load when over current occurs.

The Microcontroller shows the load current value and the status of the

Transformers in an ' 'isplay.


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CHAPTER 3

OVERALL CIRCUIT DIAGRAM

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Fig 3.1 "irc#it diagram of the Load optimization by implementing

embedded system in parallel operated transformers

3.1 CIRCUIT DIAGRAM DESCRIPTION.

3.1.1 POWER SUPPLY

$he main f#nction of a po%er so#rce is to con&ert the '"

&oltage to (" &oltage at the re)#ired le&el. *ince all electronic

circ#its %orks only %ith lo% (" &oltage %e need a po%er so#rce

#nit to pro&ide the appropriate &oltage s#pply.' +5, (" s#pply is

re)#ired for microcontroller- L"( /(0L- L(s #sed in thisproect and +12, (" &oltage is re)#ired for the 12, L'*.

3.1.2 TRANSFORMER

!n isolation transformer is employed to step down the voltage from !

mains re"uired level of smaller ! voltage. The transformer rating used here is

768? D*;7-8-;7+? and operates at the fre"uency of >8H#. The secondary of the

transformer is connected to the rectifier block.

3.1.3 RECTIFIER

$t is a circuit which converts ! voltage into the pulsating ' voltage. Here

bridge rectifier is used which consists of diodes, that converts ;7? ! voltage

from the output of transformer is converted to ;7? ' voltage.

3.1.4 FILTER

$he rectied (" &oltage consists of ripple and 7#ct#ations. '

capacitor lter of 1888#F is employed to remo&e the ripple from

the (" o#tp#t of the bridge rectier. $he property of a capacitor is

allo%(" component and the blocks the '" component.

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3.1.5 REGULATOR

$he reg#lator is a de&ice %hich maintains the terminal

&oltage constant e&en if the inp#t &oltage or load c#rrent &aries.

'n :"!85- :"!12 ;ed &oltage reg#lators are #sed in this circ#it.

$he f#nction of thesereg#lator is to pro&ide a +5, -+12, constant

(" s#pply- e&en there are 7#ct#ation in the reg#lator inp#t. $his

reg#lator helps to maintain a constant &oltage thro#gho#t the

circ#it operation.

3.1.6 DARLINGTON DRIVER

The output of the microcontroller is F>?.3ut there will be a situation where

we need to drive ;7v relays. These 'arlington drivers are open collector they

can sink current, but they cannot sourcecurrent. They are used as a ground-side

switch for all kinds of things very popular with hobbyists to control stepper motors

and relays basically, higher current loads than standard TT levels support. Here

we have used 47:86 which consists of : channel darlington array

Fig 3.2


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3.1.7CURRENT SENSOR

This is a device that detects electric ! or ' current flowing in a

conductor and gives out a corresponding signal *analogue voltage2current2digital

pulse+. The detected signal can be used for various purposes like measuring the

amount of current in the conductor, controlling of another device etc.

The !llegro !&=;7ETA-68!-T has a low-offset linear Hall sensor

circuit that has a conduction path made of copper located ne)t to the die. !

magnetic field is caused by the current flowing through the copper conductor. This

magnetic field is detected by the integrated Hall $ which converts it into a voltage

proportional to the magnetic flu). ! current of ;! flowing in a conductor produces

BBm?. The close pro)imity of the magnetic signal to the Hall transducer optimi#es

the device accuracy. To attain precision, in terms of voltage produced, a low-offset,

chopper-stabili#ed 3i-MC& Hall $ is used.

Fig 3.3


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elay is a component- %hich allo%s a lo% po%er circ#it to

s%itch a relati&ely high c#rrent on and o>- or to control signals

that m#st be electrically isolated from the controlling circ#it itself.

elays are composed of a coil of %ire aro#nd a steel core- a s%itch

and a spring that holds one or more contacts.

?hen an electrical c#rrent 7o%s thro#gh the coil it gets

energized- acting like an electromagnet. $he ref#se eld opens

the contacts and also closes the circ#it. ?hen the electrical

c#rrent stops 7o%ing- the opposite occ#rs.

Fig 3.4 *chematic of elay

3.1.10 LCD MODULE

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Fig 3.5 L"( mod#le %ith


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CHAPTER 4

MICROCONTROLLER

4.1 INTRODUCTION

! microcontroller *sometimes abbreviated J, u or M4+ is a small computer on

a single integrated circuit containing a processor core, memory, and programmable

input2output peripherals. 0rogram memory in the form of CA flash or CT0ACM

is also often included on chip, as well as a typically small amount of A!M.

4.2 PIC16F887 INTRODUCTION

Microcontroller PIC16F887 is one of the 0$Micro 9amily microcontroller

which is popular at this moment, start from beginner until all professionals.

3ecause very easy using PIC16F887 and use 9!&H memory technology so that

can be write-erase until thousand times.

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The superiority this A$& Microcontroller compared to with other

microcontroller :-bit especially at a speed of and his code compression.

PIC16F887 have 8 pin by 66 path of $2C.

PIC16F887 perfectly fits many uses, from automotive industries and

controlling home appliances to industrial instruments, remote sensors, electrical

door locks and safety devices. $t is also ideal for smart cards as well as for battery

supplied devices because of its low consumption.

EE0ACM memory makes it easier to apply microcontrollers to devices

where permanent storage of various parameters is needed *codes for transmitters,

motor speed, receiver fre"uencies, etc.+.

ow cost, low consumption, easy handling and fle)ibility make PIC16F887

applicable even in areas where microcontrollers had not previously been

considered *e)ampleG timer functions, interface replacement in larger systems,

coprocessor applications, etc.+.

$n &ystem 0rogrammability of this chip *along with using only two pins in

data transfer+ makes possible the fle)ibility of a product, after assembling and

testing have been completed.

This capability can be used to create assembly-line production, to store

calibration data available only after final testing, or it can be used to improve

programs on finished products.

04 is not different from other microcontrollers 04. 0$ microcontroller

04 consists of !rithmetic logic unit *!4+, memory unit *M4+, control unit

*4+, !ccumulator etc. we know that !4 mainly used for arithmetic operations

and taking the logical decisions, memory used for storing the instruction which is

to processed and also storing the instructions after processing, ontrol unit is used

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for controlling the all the peripherals which are connected to the 04 both internal

peripherals and e)ternal peripherals. !ccumulator is used for storing the results

and used for further processing. !s $ said earlier 0$ micro controller supports the

A$& architecture that is reduced instruction set computer

!4.3 ARCHITECTURE OF PIC16F887

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9ig .; !rchitecture of 0$;B9::=

4.3.1 M"#$%&

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This microcontroller has three types of memory- ACM, A!M and

EE0ACM. !ll of them will be separately discussed since each has specific

functions, features and organi#ation.

4.3.1.1 ROM M"#$%&

ACM memory is used to permanently save the program being e)ecuted. This

is why it is often called /program memory1. The 0$;B9::= has :5b of ACM *in

total of :;K7 locations+. &ince this ACM is made with 9!&H technology, its

contents can be changed by providing a special programming voltage *;6?+.

!nyway, there is no need to e)plain it in detail because it is automatically

performed by means of a special program on the 0 and a simple electronic device

called the 0rogrammer.

4.3.1.2 EEPROM M"#$%&

&imilar to program memory, the contents of EE0ACM is permanently saved,

even the power goes off. However, unlike ACM, the contents of the EE0ACM can

be changed during operation of the microcontroller. That is why this memory *7>B

locations+ is a perfect one for permanently saving results created and used during

the operation.

4.3.1.3 RAM M"#$%&

This is the third and the most comple) part of microcontroller memory. $n

this case, it consists of two partsG general-purpose registers and special-function

registers *&9A+.Even though both groups of registers are cleared when power goes

off and even though they are manufactured in the same way and act in the similar

way, their functions do not have many things in common.

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4.3.2 G"'"%()P*%+$," R"-,/"%,

Leneral-0urpose registers are used for storing temporary data and results

created during operation. 9or e)ample, if the program performs a counting *for

e)ample, counting products on the assembly line+, it is necessary to have a register

which stands for what we in everyday life call /sum1.

&ince the microcontroller is not creative at all, it is necessary to specify the

address of some general purpose register and assign it a new function. ! simple

program to increment the value of this register by ;, after each product passes

through a sensor, should be created.

Therefore, the microcontroller can e)ecute that program because it now

knows what and where the sum which must be incremented is. &imilarly to this

simple e)ample, each program variable must be pre assigned some of general-

purpose register.

4.3.3 SFR R"-,/"%,

&pecial-9unction registers are also A!M memory locations, but unlike

general-purpose registers, their purpose is predetermined during manufacturing

process and cannot be changed. &ince their bits are physically connected to

particular circuits on the chip *!2' converter, serial communication module, etc.+,

any change of their contents directly affects the operation of the microcontroller or

some of its circuits.

9or e)ample, by changing the TA$&! register, the function of each port !

pin can be changed in a way it acts as input or output. !nother feature of these

memory locations is that they have their names *registers and their bits+, which

considerably facilitates program writing. &ince high-level programming language

can use the list of all registers with their e)act addresses, it is enough to specify the

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register@s name in order to read or change its contents.

4.3.4 RAM M"#$%& B('0,

The data memory is partitioned into four banks. 0rior to accessing some

register during program writing *in order to read or change its contents+, it is

necessary to select the bank which contains that register. Two bits of the &T!T4&

register are used for bank selecting, which will be discussed later. $n order to

facilitate operation, the most commonly used &9As have the same address in all

banks which enables them to be easily accessed.

4.3. STACK

! part of the A!M used for the stack consists of eight ;6-bit registers.

3efore the microcontroller starts to e)ecute a subroutine *! instruction+ or

when an interrupt occurs, the address of first ne)t instruction being currently

e)ecuted is pushed onto the stack, i.e. onto one of its registers.

$n that way, upon subroutine or interrupt e)ecution, the microcontroller

knows from where to continue regular program e)ecution. This address is cleared

upon return to the main program because there is no need to save it any longer, and

one location of the stack is automatically available for further use.

$t is important to understand that data is always circularly pushed onto the

stack. $t means that after the stack has been pushed eight times, the ninth push

overwrites the value that was stored with the first push. The tenth push overwrites

the second push and so on. 'ata overwritten in this way is not recoverable. $n

addition, the programmer cannot access these registers for write or read and there

is no &tatus bit to indicate stack overflow or stack underflow conditions. 9or that

reason, one should take special care of it during program writing.

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4.3.6 I'/"%%*+/ S&,/"#

The first thing that the microcontroller does when an interrupt re"uest

arrives is to e)ecute the current instruction and then stop regular program

e)ecution. $mmediately after that, the current program memory address is

automatically pushed onto the stack and the default address *predefined by the

manufacturer+ is written to the program counter.That location from where the

program continues e)ecution is called the interrupt vector. 9or the 0$;B9::=

microcontroller, this address is 888h. !s seen in 9ig. ;-= below, the location

containing interrupt vector is passed over during regular program e)ecution. 0art

of the program being activated when an interrupt re"uest arrives is called the

interrupt routine. $ts first instruction is located at the interrupt vector.

How long this subroutine will be and what it will be like depends on the

skills of the programmer as well as the interrupt source itself. &ome

microcontrollers have more interrupt vectors *every interrupt re"uest has its

vector+, but in this case there is only one. onse"uently, the first part of the

interrupt routine consists in interrupt source recognition. 9inally, when theinterrupt source is recogni#ed and interrupt routine is e)ecuted, the microcontroller

reaches the AET9$E instruction, pops the address from the stack and continues

program e)ecution from where it left off.

4.4 PIN DIAGRAM

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9ig .7 0in diagram of 0$;B9::=

4. FEATURES OF PIC16F887

The 0$;B9::=! is one of the latest products from Microchip. $t features all

the components which modern microcontrollers normally have. 9or its low price,

wide range of application, high "uality and easy availability, it is an ideal solution

in applications such asG the control of different processes in industry, machine

control devices, measurement of different values etc. &ome of its main features are

listed below.

• A$& architecture

Cnly 6> instructions to learn

!ll single-cycle instructions e)cept branches

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• Cperating fre"uency ;;.8>K7 MH#

• 0recision internal oscillator

9actory calibrated

&oftware selectable fre"uency range of :MH# to 6;5H#

• 0ower supply voltage 7.8->.>?

onsumptionG 778u! *7.8?, MH#+, ;;u! *7.8 ?, 67 5H#+ >8n!

*stand-by mode+

• 0ower-&aving &leep Mode

• 3rown-out Aeset *3CA+ with software control option

• 6> input2output pins

High current source2sink for direct E' drive

software and individually programmable pull-up resistor

$nterrupt-on-hange pin

• :5 ACM memory in 9!&H technology

hip can be reprogrammed up to ;88,888 times

• $n-ircuit &erial 0rogramming Cption

hip can be programmed even embedded in the target device

• 7>B bytes EE0ACM memory

'ata can be written more than ;,888,888 times

• 6B: bytes A!M memory

• !2' converter

;-channels

;8-bit resolution

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• 6 independent timers2counters

• Watch-dog timer

• !nalogue comparator module with

Two analogue comparators

9i)ed voltage reference *8.B?+

0rogrammable on-chip voltage reference

• 0WM output steering control

• Enhanced 4&!AT module

&upports A&-:>, A&-767 and $7.8

!uto-3aud 'etect

• Master &ynchronous &erial 0ort *M&&0+

supports &0$ and $7 mode

4.6 LIST OF PORTS

T!3E .; 0$;B9::= 0CAT&

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4.7 PIN DESCRIPTION

T!3E .7*a+ 0$;B9::= 0$ 'E&A$0T$C

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T!3E .7*b+ 0$;B9::=0$ 'E&A$0T$C

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4.8 I'/"%'() P"%+"%(),

9ig .6 $nternal 0eripherals

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4. MEMORY ORGANIATION OF PIC16F887

9ig .

Memory

organi#ation of 0$;B9::=

2!


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CHAPTER

TRANSFORMER

.1 TRANSFORMER

! /%(',5$%#"% is an electrical device that transfers energy between two or

more circuits through electromagnetic induction. ! varying current in the

transformer%s primary winding creates a varying magnetic flu) in the core and a

varying magnetic field impinging on the secondary winding. This varying magnetic

field at the secondary induces a varying electromotive force *EM9+ or voltage in the

secondary winding. Making use of 9araday%s aw in con(unction with high magnetic

permeability core properties, transformers can thus be designed to efficiently

change ! voltages from one voltage level to another within power networks.

Transformers range in si#e from A9 transformers less than a cubic centimetre in

volume to units interconnecting the power grid weighing hundreds of tons and is

shown in 9ig.>.;

9ig.>.;. Transformer

.2.1 IDEAL TRANSFORMER

29

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$t is very common, for simplification or appro)imation purposes, to analy#e

the transformer as an ideal transformer model as represented in the two images. !n

ideal transformer is a theoretical, linear transformer that is lossless and perfectly

coupled that is, there are no energy losses and flu) is completely confined within

the magnetic core. 0erfect coupling implies infinitely high core magnetic

permeability and winding inductances and #ero net magneto motive force. ! varying

current in the transformer%s primary winding creates a varying magnetic flu) in the

core and a varying magnetic field impinging on the secondary winding. This varying

magnetic field at the secondary induces a varying electromotive force *EM9+ or

voltage in the secondary winding. The primary and secondary windings are wrapped

around a core of infinitely high magnetic permeability so that all of the magnetic flu)

passes through both the primary and secondary windings.

.2.2 REAL TRANSFORMER

The ideal transformer model neglects the following basic linear aspects in real

transformers.

• Hysteresis losses due to nonlinear application of the voltage applied in the

transformer core

• Eddy current losses due to (oule heating in the core that are proportional to

the s"uare of the transformer%s applied voltage.

• $n addition to this there will be copper loss.

• oule losses due to resistance in the primary and secondary windings

• eakage flu) that escapes from the core and passes through one winding

only resulting in primary and secondary reactive impedance.

38

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.2.3 CORE AND SHELL FORM OF TRANSFORMERS

losed-core transformers are constructed in %core form% or %shell form%. When

windings surround the core, the transformer is core form when windings are

surrounded by the core, the transformer is shell form. &hell form design may be more

prevalent than core form design for distribution transformer applications due to the

relative ease in stacking the core around winding coils. ore form design tends to, as

a general rule, be more economical, and therefore more prevalent, than shell form

design for high voltage power transformer applications at the lower end of theirvoltage and power rating ranges *less than or e"ual to, nominally, 768 k? or

=> M?!+. !t higher voltage and power ratings, shell form transformers tend to be

more prevalent. &hell form design tends to be preferred for e)tra-high voltage and

higher M?! applications because, though more labor-intensive to manufacture, shell

form transformers are characteri#ed as having inherently better k?!-to-weight ratio,

better short-circuit strength characteristics and higher immunity to transit damage.

.2.4 INDING

The conducting material used for the windings depends upon the application,

but in all cases the individual turns must be electrically insulated from each other to

ensure that the current travels throughout every turn. 9or small power and signal

transformers, in which currents are low and the potential difference between ad(acent

turns is small, the coils are often wound from enameled magnet wire, such as t wire.arger power transformers operating at high voltages may be wound with copper

rectangular strip conductors insulated by oil-impregnated paper and blocks

of pressboard is shown in 9ig.>.7.

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9ig.>.7. Winding

.2. COOLING

To place the cooling problem in perspective, the accepted rule of thumb is that

the life e)pectancy of insulation in all electric machines including all transformers is

halved for about every = to ;8 increase in operating temperature, this life

e)pectancy halving rule holding more narrowly when the increase is between about

= to : in the case of transformer winding cellulose insulation. &mall dry-type

and li"uid-immersed transformers are often self-cooled by natural convection

and radiation heat dissipation. !s power ratings increase, transformers are often

cooled by forced-air cooling, forced-oil cooling, water-cooling, or combinations of

these. arge transformers are filled with transformer oil that both cools and insulates

the windings.

.3 TYPES OF TRANSFORMER

• !utotransformer G Transformer in which part of the winding is common to

both primary and secondary circuits.

• apacitor voltage transformer G Transformer in which capacitor divider is

used to reduce high voltage before application to the primary winding.

32

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• 'istribution transformer, power transformer G $nternational standards make a

distinction in terms of distribution transformers being used to distribute

energy from transmission lines and networks for local consumption and

power transformers being used to transfer electric energy between the

generator and distribution primary circuits.

• 0hase angle regulating transformer G ! speciali#ed transformer used to

control the flow of real power on three-phase electricity transmission

networks.

• &cott-T transformer G Transformer used for phase transformation from three-

phase to two-phase and vice versa.

• 0olyphase transformer G !ny transformer with more than one phase.

• Lrounding transformerG Transformer used for grounding three-phase circuits

to create a neutral in a three wire system, using a wye-delta transformer or

more commonly, a #ig#ag grounding winding.

• eakage transformer G Transformer that has loosely coupled windings.

• Aesonant transformer G Transformer that uses resonance to generate a high

secondary voltage.

•!udio transformer G Transformer used in audio e"uipment.

• Cutput transformer G Transformer used to match the output of a valve

amplifier to its load.

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• $nstrument transformer G 0otential or current transformer used to accurately

and safely represent voltage, current or phase position of high voltage or

high power circuits.

.4 LOSSES IN TRANSFORMER

!n ideal transformer is the one which is ;88N efficient. This means that the

power supplied at the input terminal should be e)actly e"ual to the power supplied

at the output terminal, since efficiency can only be ;88N if the output power is

e"ual to the input power with #ero energy losses. 3ut in reality, nothing in this

universe is ever ideal. &imilarly, since the output power of a transformer is never

e)actly e"ual to the input power, due a number of electrical losses inside the core

and windings of the transformer, so we never get to see a ;88N efficient

transformer. Transformer is a static device, i.e. we do not get to see any movements

in its parts, so no mechanical losses e)ist in the transformer and only electrical

losses are observed. &o there are two primary types of electrical losses in the

transformerG

1 opper losses

7 $ron losses

Cther than these, some small amount of power losses in the form of Ostray losses@

are also observed, which are produced due to the leakage of magnetic flu).

.4.1 COPPER LOSS

These losses occur in the windings of the transformer when heat is

dissipated due to the current passing through the windings and the internal

resistance offered by the windings. &o these are also known as ohmic losses or $7A

losses, where O$@ is the current passing through the windings and A is the internal

resistance of the windings.

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These losses are present both in the primary and secondary windings of the

transformer and depend upon the load attached across the secondary windings

since the current varies with the variation in the load, so these are variable losses.

Mathematically, these copper losses can be defined asG

0ohmic P $ pA p F $sA s

.4.2 IRON LOSS

These losses occur in the core of the transformer and are generated due to

the variations in the flu). These losses depend upon the magnetic properties of the

materials which are present in the core, so they are also known as iron losses, as

the core of the Transformer is made up of iron. !nd since they do not change like

the load, so these losses are also constant.

There are two types of $ron losses in the transformerG

1 Eddy urrent losses

7 Hysteresis oss

.4.2.1 EDDY CURRENT LOSS

When an alternating current is supplied to the primary windings of the

transformer, it generates an alternating magnetic flu) in the winding which is then

induced in the secondary winding also through 9araday@s law of electromagnetic

induction, and is then transferred to the e)ternally connected load. 'uring this

process, the other conduction materials of which the core is composed of also gets

linked with this flu) and an emf is induced.

3ut this magnetic flu) does not contribute anything towards the e)ternally

connected load or the output power and is dissipated in the form of heat energy. &o

such losses are called Eddy urrent losses and are mathematically e)pressed asG

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0e P 5 e fQ 5 f Q 3mQ

Where

•

5 e P onstant of Eddy urrent

• 5 f Q P 9orm onstant

• 3m P &trength of Magnetic 9ield

.4.2.2 HYSTERESIS LOSS

Hysteresis loss is defined as the electrical energy which is re"uired to realign

the domains of the ferromagnetic material which is present in the core of the

transformer.

These domains lose their alignment when an alternating current is supplied

to the primary windings of the transformer and the emf is induced in the

ferromagnetic material of the core which disturbs the alignment of the domains and

afterwards they do not realign properly. 9or their proper realignment, some

e)ternal energy supply, usually in the form of current is re"uired. This e)tra energy

is known as Hysteresis loss.

Mathematically, they can be defined as

R0h P 5 h 3m;.B f?

These are the different kinds of losses happened to occur in transformer and

an electrical engineer must take care of their losses and try to reduce them as low

as possible.

Transformer has two states of operations, one is without load and the other is

with load. Most of these errors appear when the load is applied on the transformer.

&o it is essential to read the behaviour of transformer when load is applied on it,

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