Download TRANSFORMER

INFORMATIONAL TECHNOLOGY
IN EDUCATION
Name: Farah Eliza
Binti Mansor
Matrix: db130320
Name:Nurul
Qurraisyia Binti
Zulkafli
Matrix: DB130085
Name:
Fatinnazihah Binti
Abdul Rahman
Matrix: DB130322
Name: Faridah
Zahirah Binti Ismail
Matrix: Db130321
CONTENTS
No
Title
1
1.0 Introduction
2
2.0 Basic Construction Of A Transformer
2.1 Core
2.2 Windings
3
3.0 Operation Of Transformers
3.1 Winding Ratio
3.2 Voltage Ratio
3.3 Current Ratio
4
4.0 Loss And Efficiency Of Transformers
4.1 Ideal Transformers
4.2 Non-ideal Transformers
4.3 Transformers Efficiency
5
5.0 Application Of A Power Transformer
6
Quiz
INTRODUCTION OF
TRANSFORMER

Electrical device that transfers electrical energy from one
circuit to another

Made up of two electromagnetic coils

Self inductance
 Mutual inductance

Only operate with AC or DC that is constantly changing
2.0 BASIC CONSTRUCTION OF A TRANSFORMER

Consist of 2 conductor wound around a core as shown in Figure 1.2.1
Figure 1.2.1

Core is wounded with insulated copper conductor with specific number of turns
2.1 CORE

Constructed by : laminated sheets of silicon steel insulated from each other
:soft iron , powdered iron and ferrite

Thickness of the laminated sheets : between 1mm – 5 mm

Charecteristics : robust , low hysteresis
 Made
 Two
up of thin layers (Avoid power loss by the build-up of eddy currents )
major construction of the core of transformer
 Shell-type form (
E-I)
 Core-type form (U-I)
2.2 WINDINGS

Transformer consist of 2 kind of windings around the core
 Winding that
is connected to the voltage source ( primary winding )
 Winding that
is connected to load circuit and is the output path for the
transformer
( secondary winding )


In an auto transformer , one winding serves as both the primary and secondary
winding . The secondary winding is tapped from the primary winding
Types of winding methods :

Common winding

Coupling winding
TYPES AND SYMBOLS OF TRANSFORMERS
Transformer
Name
Air-core
Transformer
Iron-core
Transformer
Iron
Powder-core
Transformer
Auto
Transformer
Centre-tapped
Transformer
Multiple
Winding
Transformers
Types Of
Core
Air-core
Iron-core
Powdered
Iron-core
Iron-core
Iron-core
Iron-core
Symbol
BASIC OPERATION OF TRANSFORMERS
3.1 WINDING RATIO
 Ratio
of number of turn in the primary winding to the number of turn in the secondary winding
winding ratio , n =
𝒏𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒕𝒖𝒓𝒏𝒔 𝒊𝒏 𝒕𝒉𝒆 𝒑𝒊𝒎𝒂𝒓𝒚 𝒘𝒊𝒏𝒅𝒊𝒏𝒈
𝒏𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒕𝒖𝒓𝒏𝒔 𝒊𝒏 𝒕𝒉𝒆 𝒔𝒆𝒄𝒐𝒏𝒅𝒂𝒓𝒚 𝒘𝒊𝒏𝒅𝒊𝒏𝒈
=
𝑵𝟏
𝑵𝟐
 Step
up transformer : number of turns in secondary winding exceed the number of turns in the
primary winding
 Step
down transformer : number of turns in primary winding exceed the number of turns in the
secondary winding
 Isolation transformer :
same number of turns in primary and secondary winding
3.2 VOLTAGE RATIO

Ratio between the primary voltage , V1 and the secondary voltage V2 is called the
voltage ratio of a transformer
𝐩𝐫𝐢𝐦𝐚𝐫𝐲 𝐯𝐨𝐥𝐭𝐚𝐠𝐞
Formula of voltage ratio : 𝐬𝐞𝐜𝐨𝐧𝐝𝐚𝐫𝐲 𝐯𝐨𝐥𝐭𝐚𝐠𝐞 =

𝐕𝟏
𝐕𝟐
Voltage ratio is related to the winding ratio.
𝑽
𝑵
Formula of voltage ratio : 𝑽𝟏 = 𝑵𝟏 = n
𝟐
𝟐
3.3 CURRENT RATIO

When AC supply is connected to transformer’s primary winding , the existing flux around the winding
produces self – induction

Flux shifts to secondary winding through the transformer core to produce inductance at the
secondary winding

This indicates the emf at the secondary winding is equivalent to the emf of the primary winding
LOSS AND EFFICIENCY OF TRANSFORMERS
4.1 IDEAL TRANSFORMERS
An Ideal Transformer is an imaginary transformer which does not have any loss in it, means no core losses,
copper losses and any other losses in transformer. Efficiency of this transformer is considered as 100%.
4.2 NON-IDEAL TRANSFORMER
We can replace a nonideal transformer with an idealized transformer by including a lumped resistance
equal to the winding resistance of series with each winding

The efficiency is less than 100% because power losses in corand its primary windings.
Power loss : iron & copper
4.3 TRANSFORMER EFFICIENCY

For an ideal transformer, the power received by the load is equivalent to the power transferred by the primary
winding

Non-ideal transformer does not reach 100% efficiency because there is power loss that is unavoidable in the core
and winding

By choosing an optimum size for your winding wire and designing a suitable core that reduces iron loss to
minimum, up to 99.5% efficiency can be achieved

Transformer efficiency, 𝒏 =

Non-ideal transformer , 𝐡 =
( 𝒐𝒖𝒕𝒑𝒖𝒕 𝒑𝒐𝒘𝒆𝒓 )
𝒊𝒏𝒑𝒖𝒕 𝒑𝒐𝒘𝒆𝒓
𝒙 𝟏𝟎𝟎%
𝐨𝐮𝐭𝐩𝐮𝐭 𝒑𝒐𝒘𝒆𝒓
𝐩𝐨𝐰𝐞𝐫 𝐥𝐨𝐬𝐬 + 𝐨𝐮𝐭𝐩𝐮𝐭 𝒑𝒐𝒘𝒆𝒓
𝒙 𝟏𝟎𝟎%
OR 𝒏 =
𝑰𝟐 𝑽𝟐 𝒄𝒐𝒔 𝜽
( 𝑷𝒄𝒐𝒑𝒑𝒆𝒓 + 𝑷𝒊𝒓𝒐𝒏 ) +𝑰𝟐 𝑽𝟐 𝒄𝒐𝒔 𝜽
V2 = Output voltage or secondary voltage
I2 = Secondary current
Cos = power factor at the load
Pcopper = copper loss
Piron = iron loss
𝒙 𝟏𝟎𝟎%
5.0 APPLICATION OF POWER TRANSFORMER

The most important uses and applications of a transformer are:
1)
It can rise or lower the level of level of Voltage or Current
2)
It can increase or decrease the value of capacitor, an inductor or resistance in
an AC circuit.
3)
It can act as an impedance transferring device.
4)
It can be used to prevent DC from passing from one circuit to the other.
5)
It can isolate two circuits electrically
QUIZ
1. By referring to the figure , calculate the winding ratio of the transformer .
Answer : 4:3
2. A step up transformer as shown in figure below has a turns ratio of 1:4 and is connected to a voltage source of 240
V , 50 Hz . Calculate :
a)
The secondary voltage
b)
The numbers of turn in the secondary winding
if the number of turns in the primary winding is 480
Answer : a) 960V b) 1920
CHECK ANSWER SCHEMES
3. Figure shows a transformer with a turn ratio of 3:2 is connected to a 240V voltage source
. If a resistive load of 1Ω is connected to the terminal of the secondary winding , calculate
the quantities below :
a)Secondary voltage
b)Secondary current
c)Primary current
Answer : V2 = 160V , I2 = 0.16A , I1 = 0.11A
4. A 20kVA transformer with 0.8 power factor has a power loss comprising of 400W iron
loss and 600W copper loss . Calculate the efficiency of the transformer operating at
(a) full load (b) half load
Answer : a) 94.1% b) 91.95%
CHECK ANSWER SCHEMES
THE END
HAPPY LEARNING !