Physics Investigatory -Transformers

7/25/2019 Physics Investigatory -Transformers

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PHYSICSPHYSICSPROJECTPROJECT


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Certifcate

Acknowledgement

AIM

Principle

Introduction o transormer

Construction

Theory and working


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Energy losses

Material required

Circuit diagram

Procedure

Oser!ation conclusion

Precaution

"ources o error

#ses o transormer

iliography


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This is to certiy that the pro$ect work titled %To

investigate the relation between input and output

voltage of a TRANSFORMER %eing sumitted as aPro$ect &eport or the ulfllment o curriculum o

CE'T&A( )OA&* O+ "ECO'*A&, E*#CATIO'

-C)"E./ is a record o a onafde work carried out

y Sanskriti rom 0ueen Mary1s "chool/ 'orthend

under my guidance and super!ision during the

session April 2345 6 March 23478

E9AMI'E&Mrs8 'eha :hannaP;T -Physics. Teacher0ueen Mary1s "choolModel Town/ *elhi


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To investigate the

relation between theratio of

i) Input and Output

voltage


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ii) u!ber of turns in

the se"ondar# "oil andpri!ar# "oil of a self

designed transfor!er$

% transfor!er "onsistsof two ele"tri"all#


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isolated "oils and

operates on &arada#'sprin"ipal of (!utualindu"tion* in whi"han E+& is indu"ed in

the transfor!ersse"ondar# "oil b# the!agneti" ,u-generated b# the

voltages and "urrents,owing in the pri!ar#"oil winding$


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I'T&O*#CTIO'

O+

T&A'"+O&ME&A transformer is an electrical device that is

used to convert alternating current at low

voltage or visa versa, through electromagnetic

induction. If it increases the input voltage

then it is called step-up transformer and if it

decreases the input voltage then it is called

step-down transformer. It is based on mutual

inductancebetween two or more winding that is

responsible for transformation action in anelectrical transformer.
https://en.wikipedia.org/wiki/Electromagnetic_inductionhttps://en.wikipedia.org/wiki/Electromagnetic_inductionhttps://en.wikipedia.org/wiki/Electromagnetic_inductionhttps://en.wikipedia.org/wiki/Electromagnetic_induction


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A varying current in the transformer's primary

winding creates a varying magnetic fluxin the

transformer core and a varying magnetic fieldimpinging on the transformer's secondary

winding. This varying magnetic fieldat the

secondary winding induces a

varying electromotive force(!"# or voltage in

the secondary winding. !a$ing use

of "araday's %awin con&unction withhigh magnetic permeabilitycore properties,

transformers can thus be designed to

efficiently change Avoltages from one

voltage level to another within power networ$s.

ince the invention of the first

constant potentialtransformer in )**+,

transformers have become essential for the

Atransmission, distribution, and utiliation of

electrical energy./

A wide range oftransformer designs is encountered in

electronic and electric power applications.

Transformers range in sie
https://en.wikipedia.org/wiki/Magnetic_fluxhttps://en.wikipedia.org/wiki/Magnetic_fieldhttps://en.wikipedia.org/wiki/Electromotive_forcehttps://en.wikipedia.org/wiki/Faraday's_law_of_inductionhttps://en.wikipedia.org/wiki/Permeability_(electromagnetism)https://en.wikipedia.org/wiki/Alternating_currenthttps://en.wikipedia.org/wiki/Potential_energyhttps://en.wikipedia.org/wiki/Electric_power_transmissionhttps://en.wikipedia.org/wiki/Electric_power_distributionhttps://en.wikipedia.org/wiki/Transformer#cite_note-Bedell_.281942.29-3https://en.wikipedia.org/wiki/Magnetic_fluxhttps://en.wikipedia.org/wiki/Magnetic_fieldhttps://en.wikipedia.org/wiki/Electromotive_forcehttps://en.wikipedia.org/wiki/Faraday's_law_of_inductionhttps://en.wikipedia.org/wiki/Permeability_(electromagnetism)https://en.wikipedia.org/wiki/Alternating_currenthttps://en.wikipedia.org/wiki/Potential_energyhttps://en.wikipedia.org/wiki/Electric_power_transmissionhttps://en.wikipedia.org/wiki/Electric_power_distributionhttps://en.wikipedia.org/wiki/Transformer#cite_note-Bedell_.281942.29-3


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from 0"transformers less than a cubic

centimeter in volume to units interconnecting

the power gridweighing hundreds of tons.

A transormer consists o a rectangular shatiron core made o laminated sheets/ wellinsulated rom one another8 Two coils p4< p2and s4< s2are wound on the same core/ ut

are well insulated with each other8 'ote thatoth the coils are insulated rom the core/ thesource o alternating E8M8+88 is connected to p4< p2/ the primary coil and a load resistance &is connected to s4s2/ the secondary coilthrough an open switch "8 Thus there can eno current through the secondary coil so longas the switch is open8

+or an ideal transormer/ we assume that theresistance o the primary < secondarywinding is negligile8 +urther/ the same =u>
https://en.wikipedia.org/wiki/RFhttps://en.wikipedia.org/wiki/Power_gridhttps://en.wikipedia.org/wiki/RFhttps://en.wikipedia.org/wiki/Power_grid


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links oth the primary and secondary coil as!ery little =u> escape rom the core i8e8energy loss is also negligile8

T?EO&, A'*

@O&:I'; O+T&A'"+O&ME&@hen an altering E8M8+88 is supplied to the primary

coil p4p2/ an alternating current starts alling in it8The altering current in the primary coil produces a

changing magnetic =u>/ which induces altering

!oltage in the primary as well as in the secondary

coil8 In a goodtransormer/ whole o the magnetic

=u> linked with primary coil is also linked with thesecondary coil8 Then the induced E8M8+88/ induced in

each turn o the secondary coil is equal to that

induced in each turn o the primary coil8


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Thus i Epand Ese the instantaneous !alues o the

E8M8+881s induced in the primary coil and the

secondary coil8

(et 'pand 'sare the no8 o turns o the primary

and secondary coils o the transormer respecti!ely8

dB dt rate o change o magnetic =u> in each

turn o primary and secondary coil at a time t

The induced E8M8+88 in the primary coilD

Ep 'pdBdt -4. And

The induced E8M8+88 in the secondary coilD

Es 'sdBdt -2.

"ince the ao!e relations are true at e!ery instant/so y di!iding 2 y 4/ we get

EsB Ep 'sB

'p: -.

@here : Transormation &atio

As Epis the instantaneous !alue o ack E8M8+8induced in the primary coil p4/ so the instantaneous


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current in primary coil is due to the diFerence -E 6Ep. in the instantaneous !alues o the applied andack E8M8+88 +urther i &pis the resistance o p4p2

coil/ then the instantaneous current Ip in theprimary coil is gi!en y

Ip E 6 EpB &p

E 6 Ep Ip&p

@hen the resistance o the primary coil is small/ &p< Ipcan e neglected so thereore

E 6 Ep 3 or Ep E

Thus ack E8M8+8 input E8M8+8

?ence equation -. can e written as

EsB Ep EsB E

output E8M8+8 B inputE8M8+8

'sB 'p :

@here : is constant/ called turn or transormationratio8

In a step up transormer

EsG E so : G 4/ hence 'sG 'p

In a step down transormer


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EsH E so : H 4/ hence 'sH 'p

I/

Ip !alue o primary current at the same instant t

And/

Is !alue o sec8 current at this instant/ then

Thereore/

Input power at the instant t EpIp

And/

Output power at the same instantEsIs

I there are no loss o power in the transormer

-433 eJciency./Then/

Input power output power

EpIp EsIs

EsB Ep IpB Is 'sB 'p :

In a step up transormer

As k G 4/ so IpG Isor IsH Ip


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i8e8 current in secondary coil is weaker whensecondary coil1s !oltage is higher and numer oturns is greater than that o the primary coil8

?ence/ whate!er we gain in !oltage/ we lose incurrent in the same ratio8

"imilarly it can e shown/ that in a step downtransormer/ whate!er we lose in !oltage/ we gainin current in the same ratio8

Thus a step up transormer in reality steps downthe current < a step down transormer steps up thecurrent8

EJciencyDEJciency o a transormer is defned as the ratio ooutput power to the input power8 i8e8

output power B input power

EsIsB EpIp

Thus in an ideal transormer/ where there is nopower losses/ 48 )ut in actual practice/ thereare many power lossesK thereore the eJciency o

transormer is less than one8


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Energy lossesDI8 +lu> (eakageD

There is always some =u> leakageK that is/ not all

o the =u> due to primary passes through thesecondary due to poor designs o core or the airgaps in the core8 It can e reduced y winding theprimary and secondary coils one o!er the other8

II8 &esistance o the windingsD

The wire used or windings has some resistance or

so/ energy is lost due to heat produced in the wire-I2&.8 In high current/ low !oltage windings/ theseare minimiLed y using thick wires8

III8 Eddy currentsD

The alternating magnetic =u> induces eddycurrents in the iron core and causes heating8 ThiseFect is reduced y ha!ing a laminated core8

I8 ?ysteresisD

The magnetiLation o the core is repeatedlyre!ersed y the alternating magnetic feld8 Theresulting e>penditure o energy in the core


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appears as heat and is kept to a minimum yusing a magnetic material which has a lowhysteresis loss8


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MATE&IA(&E0#I&E*

An Iron rod

Copper wires o diFerent gauge

-diameter. Two A8C8 !oltmeter

Two A8C8 Ammeters


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48 Take a thick iron rod and co!er it with athick paper and wind a large numer oturns o thin Cu wire on thick paper8 This

constitutes primary coil o the transormer828 Co!er the primary coil with a sheet o

paper and wound relati!ely smallernumer o turns o thick copper wire on it8

This constitutes the secondary coil8 It is astep down transormer8

8 Connect P4P2to A8C8 mains and measurethe input !oltage and current/ using A8C8!oltmeter and ammeter respecti!ely8

N8 "imilarly/ measure the output !oltage andcurrent through "4"28

58 'ow connect the "4"2to A8C8 mains andagain measure !oltage and current

through primary and secondary coil ostepup transormer8

78 &epeat all steps or other sel madetransormer y changing numer oprimary turns in secondary coils8


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48 (east count o A8C8 !oltmeter

28 ero error o !oltmeter

8 &ange o !oltmeter

N8 (east count o A8C8 ammeter

58 ero error o ammeter


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78 &ange error o ammeter

Q8 Applied A8C8 !oltage

O)"E&ATIO' TA)(E


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4.

The output !oltage o the transormer across

the secondary coil depends upon the turn

ratio -'"B'P. w8r8t8 input !oltage8

2. The output current o the transormer

across the secondary coil depends upon

the turn ratio -'"B'P. w8r8t8 input current8

. There is loss o power etween input and

output coil o a transormer8


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PrecautionsA8 :eep sae yoursel rom the high

!oltage8

)8 @hile taking the readings ocurrent and !oltage/ the A8C8 mainsupply should remain constant8

"ources oerrorA8 alues o current can e changed

due to heating eFect o current8)8 The eddy current can change the

readings8


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#"E" O+

T&A'"+O&ME&

o A transformer is used in almost all A.C.

operations

In voltage regulator for T.V., refrigerator,

computer, air conditioner etc.

In the induction furnaces. A step down transformer is used for welding

purposes.

A step down transformer is used for obtaining

large current.

A step up transformer is used for the

production of X-Ras and !"#!

advertisement.

Transformers are used in voltage regulators

and stabili$ed power supplies.


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Transformers are used in the transmissions of

A.C. over long distances.

%mall transformers are used in Radio sets,telephones, loud spea&ers and electric bells etc.

)I)(IO;&AP?,

)ooksD

.$Co!prehensive Pra"ti"al Ph#si"s b# /a-!iPubli"ations 0P) /td$

1$CERT Ph#si"s "lass 2II3$/ab +anual Ph#si"s b# Saraswati Publi"ations

@esitesD


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.$ https455en$wi6ipedia$org5wi6i5transfor!ers

1$ www$s"ien"edire"t$"o!5s"ien"e5arti"le5p

ii3$ http455www$ele"troni"s$"o!5transfor!er7"onstru"tion$ht!l

8$ http455www$ele"tri"al8u$"o!5what7is7transfor!er7de9nition7wor6ing7prin"iple7of7transfor!er5
https://en.wikipedia.org/wiki/transformershttps://en.wikipedia.org/wiki/transformershttps://en.wikipedia.org/wiki/transformershttp://www.sciencedirect.com/science/article/piihttp://www.sciencedirect.com/science/article/piihttp://www.electronics.com/transformer-construction.htmlhttp://www.electronics.com/transformer-construction.htmlhttp://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/https://en.wikipedia.org/wiki/transformershttps://en.wikipedia.org/wiki/transformershttp://www.sciencedirect.com/science/article/piihttp://www.sciencedirect.com/science/article/piihttp://www.electronics.com/transformer-construction.htmlhttp://www.electronics.com/transformer-construction.htmlhttp://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/http://www.electrical4u.com/what-is-transformer-definition-working-principle-of-transformer/

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Physics Investigatory -Transformers