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PRESENTATION ON
ELECTROMEGNATISM
Presented to:
Prof Dr. Tariq Bhatti
Presented by:MUHAMMAD FAISAL RAO
Roll No:07-49
BS(IT) 3rd
Dept. of Computer ScienceBahauddin zakariyauniversity, Multan
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Transformer
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Transformer
A transformer is a
device that
transfers electrical
energy from onecircuit to another
through inductively
coupled electrical
conductors
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Transformer
A transformer is a device thattransfers electrical energy from
one circuit to another through
inductively coupled electrical
conductors.
A changing current in the first
circuit (the primary) creates a
changing magnetic field.
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This changing magnetic field
induces a changing voltage in the
second circuit (the secondary).This effect is called mutual
induction.
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If a load is connected to thesecondary circuit, electric charge
will flow in the secondary windingof the transformer and transferenergy from the primary circuit tothe load connected in the
secondary circuit
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The secondary induced voltage VS, of
an ideal transformer, is scaled from
the primary VPby a factor equal to
the ratio of the number of turns of
wire in their respective windings:
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By appropriate selection of
the numbers of turns, a
transformer thus allows analternating voltage to be
stepped up by making NS
more than NP or stepped
down, by making it less.
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Transformers are some of the mostefficient electrical 'machines', withsome large units able to transfer
99.75% of their input power to theiroutput.
Transformers come in a range of
sizes from a thumbnail-sized couplingtransformer hidden inside a stagemicrophone to huge units weighinghundreds of tons used to interconnect
portions of national power grids.
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PRESENTATION ON
ELECTROMEGNATISM
Presented to:
Prof Dr.Tariq Bhatti
Presented by:Muhammad Qaswar
Roll No:07-27
BS(IT) 3rd
Dept. of Computer ScienceBahauddin zakariyauniversity, Multan
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Construction
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Laminated core
transformer
showing edge of
laminations at top
of unit.
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Laminated steel cores
Transformers for use at power or
audio frequencies typically have cores
made of high permeability silicon
steel.The steel has a permeability many
times that of free space, and the core
thus serves to greatly reduce themagnetising current, and confine the
flux to a path which closely couples
the windings.
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Early transformer developers soon
realized that cores constructed from
solid iron resulted in prohibitive eddy-
current losses, and their designs
mitigated this effect with cores
consisting of bundles of insulated iron
wires.
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Later designs constructed the core by
stacking layers of thin steel
laminations, a principle that has
remained in use.
Each lamination is insulated from its
neighbors by a thin non-conducting
layer of insulation.
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The effect of laminations is to confine
eddy currents to highly elliptical pathsthat enclose little flux, and so reduce
their magnitude.
Thinner laminations reduce losses, but
are more laborious and expensive to
construct.
Thin laminations are generally used on
high frequency transformers, with sometypes of very thin steel laminations able
to operate up to 10 kHz.
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Solid cores
Powdered iron cores are used in circuits(such as switch-mode power supplies) thatoperate above main frequencies and up toa few tens of kilohertz. These materials
combine high magnetic permeability withhigh bulk electrical resistivity.
For frequencies extending beyond theVHF band, cores made from non-conductive magnetic ceramic materialscalled ferrites are common. Some radio-frequency transformers also have movablecores (sometimes called 'slugs') whichallow adjustment of the coupling coefficient
(and bandwidth) of tuned radio-frequencycircuits.
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Windings
Windings are usually arranged concentrically to
minimize flux leakage
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Cut view through transformer windings.White: insulator. Green spiral: Grain
oriented silicon steel.Black: Primary winding made of oxygen-
free copper. Red: Secondary winding. Topleft: Toroidal transformer. Right: C-core,but E-core would be similar. The blackwindings are made of film. Top: Equally lowcapacitance between all ends of bothwindings. Since most cores are at leastmoderately conductive they also need
insulation. Bottom: Lowest capacitance forone end of the secondary winding neededfor low-power high-voltage transformers.
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Three-phase oil-
cooled transformerwith cover cut away.
The oil reservoir is
visible at the top.Radiative fins aid the
dissipation of heat.
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Terminals
Very small transformers will have wireleads connected directly to the endsof the coils, and brought out to thebase of the unit for circuitconnections.
Larger transformers may have heavybolted terminals, bus bars or high-voltage insulated bushings made ofpolymers or porcelain.
A large bushing can be a complexstructure since it must provide carefulcontrol of the electric field gradientwithout letting the transformer leak oil.
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A Presentation on
Types of TransformersPresented by:
Malik Ajmal
BS(IT)-07-12
Presented to:
Dr.Tariq Bhatti sb.
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Transformer
A transformer is a
device that
transfers electrical
energy from onecircuit to another
through inductively
coupled electrical
conductors
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Types of Transformers:
A wide variety of transformer designsare used for different applications.
Some important types are given as:
Auto-transformer
Poly-phase transormer
Leakage transformer
Resonant transformer
Instrument transformers
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AUTO-TRANSFORMERS
An autotransformer with a sliding
brush contact
An autotransformer has only a singlewinding with two end terminals, plus a
third at an intermediate tap point.
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POLY-PHASE TRANSFORMER
For three-phase supplies,a bank of
three individual single-phase
transformers can be used,or all three
phases can be incorporated as a
single three-phase transformer.
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LEAKAGE TRANSFORMERS
A leakage transformer,also called a
stray-field transformer, has a
significantly higher leakage
inductance than other transformers.
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RESONANT TRANSFORMERS
A resonant transformer is a kind of
the leakage transformer. It uses the
leakage inductance of its secondary
windings in combination with external
capacitors, to create one or more
resonant circuits.
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INSTRUMENT TRANSFORMERS
Current transformers, designed to be
looped around conductor.
A current transformer is ameasurement device designed to
provide a current in its secondary coil
proportional to the current flowing in
its primary.
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PRESENTATION ON
ELECTROMEGNATISM
Presented to:
Prof Dr. Tariq Bhatti
Presented by:
SHAHBAZ HUSSAIN
Roll No:07-26
BS(IT) 3rd
Dept. of Computer ScienceBahauddin zakariyauniversity, Multan
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Basic principle of Transformer:
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TRANSFORMERS
A transformer is a device that
transfers electrical energy from one
circuit to another through inductively
coupled electrical conductors.
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TRANSFORMERS RULES
Transformer is
based on two
principles:
Firstly,that anelectric current can
produce a
magnetic.
Secondly,
electromegnetic
induction
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TRANSFORMERS
By changing the
current in the primary
coil, it changes the
strength of its
magnetic field
The changing
magnetic field extends
into the secondary
coil, a voltage isinduced across the
secondary.
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Induction law
Faradays law states that:
Vs=Ns.d/dtwhere VS is the instantaneous
voltage.
NS is the number of turns in the
secondary coil.
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Since the same magnetic flux passes
through both the primary and
secondary coils in an ideal
transformer,the instantaneous voltage
across the primary coil
Vp=Np.d/dt
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Taking the ratio of the two equationsTaking the ratio of the two equations
forfor VSVSandand VPVPgives the basicgives the basic
equation for stepping up or steppingequation for stepping up or stepping
down the voltagedown the voltage
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If Ns>Np, Vs>Vp
Such transformer voltage across
secondary is greater than primaryvoltage called step up transformer.
Voltage cross secondary less than
primary voltage called step down
transformer.
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Ideal power equation
Power input=power outputVpIp=VsIs
Vs/Vp=Ip/Is
Where current is inversaly
proportional to respective voltage.
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Step up Vs Voltage increase then
secondary current reduced.
When current passes throughresistance then power loss due to
heating effect.
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THANKS!!!
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