Physics Tranformer project

7/27/2019 Physics Tranformer project

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AimTo Study the Transformers Principle, Types and its Applications.

INTRODUTION

Transformer is a static electromagnetic device that magnetically changes electric

energy from one circuit to another circuit without changing in its frequency. It can

increase or decrease the voltage level in the circuit with a similar decrease or increase

in current. In Step-up transformer,the energy is transformer into higher voltage

whereas in the Step-down transformer, the energy is transformed into lower voltage.

It is a device that has no moving parts, which converts an alternating voltage given

another AC voltage, increasing or decreasing its value, without changing the frequency.

Unlike the auto-transformer , a transformer has a galvanic isolation between the input

(primary) and output (secondary), ie no driver only electrically connects the two parts.


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It is equipped with one or more windings (winding) primary and one or more

secondary windings. The operating principle is based on the energy transfer by mutual

inductance (electromagnetic induction): AC primary winding path which creates a

magnetic field that is "captured" by the secondary winding which then transforms back

into power. The transformation ratio is influenced by the number of turns of the

primary winding with respect to the number of turns of the secondary winding. For

example, if the secondary winding has 50 turns as the primary winding has 500, the

transformation ratio will be about 10. By applying a voltage of 240V primary,

secondary issue a voltage of about 24V. In practice, the energy transfer can not be

total, a certain amount is lost. The transformer has a characteristic indicating this

property, it is the coupling coefficient, which can be optimized by choosing materials

and forms that go. Sometimes, elementary and secondary, there may be only one

winding, but with one or several taps. It is important to remember that the transformerby its nature, can not transmit DC voltage and is limited to the transfer of AC

voltages, including the range of amplitude and frequency depend on its type. There

are several kinds of processors dedicated to various areas: audio sector, high voltage,

HF, etc..

Types of Transformer

Mains transformer 3 phase transformer 2 phases High-voltage transformer Current transformer Auto Transformer Polyphase Transformer Audio Transformer Instrument Transformer
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Mains transformer

This type of transformer is commonly used in the production of power sector alone,

mostly in amateur. Industrial side, this type of component is more often replaced by

switching control systems, providing equal power, less heat, a smaller footprint, and

often a range of input voltages greater.

Note: Sometimes, a transformer is used only for issues of isolation, the output voltage

being equal to the input voltage.

3 phase transformer 2 phases

It is a bit peculiar transformer specially designed for use with three-phase primary and

secondary phases with two or vice versa. There are two types of cabling windings to

ensure this function: "Connection Leblanc" and "Connection Scott."

High-voltage transformer

Used in cars (to produce sparks candles that trigger the explosion of the fuel), in

televisions (EHV transformers for very high voltage needed to operate the CRT) in

certain consumer gadgets such as "balls plasma "or Tesla transformer (transformer

high voltage and high frequency) that produce arcs very long (over a meter). Handling

this kind of processors (when they are operating regime) can be dangerous, even

deadly, so extreme caution is required.


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Current transformer

This is a component whose principle is also based on the transfer of electromagnetic

energy between two windings, with the difference that the primary is arranged in seriesin the circuit which it is desired to know the consumption. Sometimes it is the power

wire of the circuit to be measured is the primary of the transformer (in this case, there

is no winding, a thread can just stay right), the secondary being added by the means

of a clamp which can be closed around (clamp). The interest of this method is that it

is not necessary to interrupt the power supply circuit for inserting

a measuring instrument.

Principle of operation

Mutual induction principle is followed in the working of the transformes. Transformer

has two windings which are magnetically coupled with its core. When one of the

windings called primary is energized with a sinusoidal voltage, an alternating flux is

established in both the windings.

According to Faraday's laws of electromagnetic induction, an emf is induced in the

secondary winding which is called mutually induced emf. Thus energy is transferred

from primary circuit to the secondary circuit through electromagnetic induction.

Transformer core

It magnetically couples the two windings of the transformer. By using silicon steel as

the material, Hysteresis loss in the core is reduced. In order to reduce the eddy

current loss, the core is laminated. Each laminations is of thickness 0.35mm to 0.5mm.

Types of core

There are two types of cores, namely, core type and shell type.
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Core type

In this type of transformer, the windings surround a considerable part of the core. The

individual laminations of the core are cut in the form of L shaped long strips.

Shell type

In the shell type transformers, the core surrounds a considerable part of the windings.

Other parts

Other necessary parts of transformer are as follows:

o A suitable containero An insulating mediumo Bushingso Conservationo Breather

Container

A suitable metallic container is used for housing the assembled core and the windings.

Better cooling can be obtained by increasing the surface area of the container with the

help of corrugated sheets.

Insulating mediumThe transformer windings and the metallic container are insulated from one another by

a suitable insulating medium. The transformer oil not only provides insulation but also

helps to dissipate the heat due to iron ad copper loss occulting in the transformers.

Bushings


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All the transformer leads are brought out of the container through suitable bushings.

Conservator

The function of conservator is to allow contraction and expansion of oil without

exposing it to the outside air.

Breather

It is a box containing calcium to absorb moisture of air entering the conservator as it

is well known fact that the insulating property of the transformer oil is lost even if a

small amount of moisture enters in it. So the dry air is allowed to pass in through this

breather.

Sections in transformers

Core

Primary winding

Secondary winding

Working principle

When we give supply to the primary winding in the transformer one current will be

flowing in the primary winding, this will be creating one flux, this flux will flow in the

core and this flux will be cut by the secondary winding, this will create the voltage inthe secondary winding, if we short the secondary winding by connecting the load

current will be flowing in the circuit, hence the circuit is closed.

Terms


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Primary Voltage: V1

Secondary Voltage: V2

Primary Current: I1

Secondary Current: I2

Primary Turns: N1

Secondary Turns: N2

Equation of the Transformer

I1/ I2 = V2/ V1 = N2/ N1

This Equation is called as Transformation Ratio (K).

EMF equation of the Transformer

Erms = 4.44 f N a B

Where

Erms = RMS Voltage

f = Frequency

N = Number of turns

a = Cross sectional area

B = Magnetic flux density

Classification of Transformers

Voltages (V to kV)

Power Capacity (VA to MVA)

Frequency

Cooling Type (Air, Water, Fan, Oil Cooled)


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Winding (Step down, Step Up, Multiple Windings)

Application (Impedance Matching, Power Supply, Stabilizer)

Construction

Cores

Laminated steel cores

Permeability silicon steel cores are used in the transformers of power and audio types.

Most common of laminated cores are E-Shaped and I-Shaped.

Toroidal cores

Silicon steel or Permalloy is used in the transformers. This transformer built like a ring

shaped core. These types of transformers are more efficient when compared to the E-I

shaped types.

Coolant

If temperature inside the transformers (power transformer) increases it will damage the

winding insulation. Small transformers will produce less heat only for that natural air

circulation is enough. But for large capacity transformers transformer oil is used asinsulation as well as cooling of that also.

Terminals

Small Transformers will have wire leads will be connected to the coil ends and

brought out to the circuit connections. Large Transformers may have heavy bolted

terminals.

Applications

In General electrical power is getting generated at one place getting transmitted by

cables and finally distributed with respect to the consumers.


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Suppose for example

Power generation is 11kV from neyveli we will not transmit that 11kV. We will step up

that voltage to 110 kV and again step it down to the 11kV when it reaches the

receiving end.

This is due to reduce the cable size; if we increase the voltage current will be

reduced due to current only cable size is getting selected. So small size of cables are

used. So cost is getting reduced. In this method one step up transformer as well as

step down transformer is used. This is the main advantages of the Transformers.

With the sharp increase in demand for electric power, power transformers in 400 KV

ratings were produced as early as 1950. In the early 1970s unit ratings as large as

1100 MVA were produced and 800KV transformers were manufactured in the early

1980s.

A transformeris a static piece of equipment with a complicated electromagnetic circuit

inside. The energy is transferred from one electrical circuit to another through the

magnetic field. During this transfer of electric energy the voltage only varies and the

power remains constant. The transformer works on the principle ofMutual induction.

In its simplest form, a transformer consists of two conducting coils having a mutual

inductance. In an ideal case it is assumed that all the flux linked with the primary

winding also links the secondary winding. But, in practice it is impossible to realize

this condition as magnetic fluxcannot be confined. The greater portion of the flux

flows in the core while a small portion called the leakage fluxlinks one or the other

winding. Depending upon the particular application and type of connection, a

transformer may have additional windings apart from the two conventional windings.

There are two types of transformers available. They are

* Step-up Transformer

* Step-down Transformer


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Step-up Transformer:

It is used to step-up the voltage to the required value. For example, from the

generating station, if some 11KV is produced then it is stepped up to 230 KV using

step-up transformer. It is because when 11KV is transmitted, most of the power will

go as a transmission loss. So, A step-up transformer is used here.

Step-down Transformer:

It is used to step-down the voltage at the receiving end and making it available to the

consumer.

For industries, institutions, etc., about 400 to 440V line is given. For households it is

about 230V.


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INDEX Acknowledgements Aim Introduction Types of Tranformer

Mains transformer 3 phase transformer 2 phases High-voltage transformer Current transformer

Principle of Operation Transformer Core Types of Core

Core Type Shell Type

Other Parts A suitable container An insulating medium Bushings Conservation Breather

Sections in Transformers Working Principle Construction Application


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AcknowledgementsI would like to express my sincere gratitude to my physics

mentor Mr Devendra Sir, for his vital support, guidance and

encouragement without which this project would not have

come forth. I would also like to express my gratitude to the

other staffs of the Department of Physics for their support

during the making of this project.


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Certificate

This is hereby to certify that the original and genuine investigation work has been carried out to

investigate about the subject matter and the related data collection and investigation has been

completed solely, sincerely and satisfactorily by NITIN KUMAR of CLASS XII B, Govt. Boys Sr.

Sec. School No. 3, Sarojini Nagar, New Delhi regarding his project titled Transformer Principle,

Types and its Applications.

Teachers Sign.


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ON

Name Nitin Kumar

Class 12thB

Roll No.9752452

TeacherDevendra Sir

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Physics Tranformer project

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