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 Self inductance Mutual inductance 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 up of thin layers (Avoid power loss by the build-up of eddy currents ) Two 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 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 = 𝑵 𝟏 𝑵 𝟐 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 3.3 CURRENT RATIO Ratio between the primary voltage , V1 and the secondary voltage V2 is called the voltage ratio of a transformer Formula of voltage ratio : 𝐩𝐫𝐢𝐦𝐚𝐫𝐲 𝐯𝐨𝐥𝐭𝐚𝐠𝐞 𝐬𝐞𝐜𝐨𝐧𝐝𝐚𝐫𝐲 𝐯𝐨𝐥𝐭𝐚𝐠𝐞 = 𝐕 𝟏 𝐕 𝟐 Voltage ratio is related to the winding ratio. Formula of voltage ratio : 𝑽 𝟏 𝑽 𝟐 = 𝑵 𝟏 𝑵 𝟐 = n 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= ( 𝒐𝒖𝒕𝒑𝒖𝒕 𝒑𝒐𝒘𝒆𝒓 ) 𝒊𝒏𝒑𝒖𝒕 𝒑𝒐𝒘𝒆𝒓 𝒙 𝟏𝟎𝟎% Non-ideal transformer ,𝐡= 𝐨𝐮𝐭𝐩𝐮𝐭 𝒑𝒐𝒘𝒆𝒓 𝐩𝐨𝐰𝐞𝐫 𝐥𝐨𝐬𝐬 + 𝐨𝐮𝐭𝐩𝐮𝐭 𝒑𝒐𝒘𝒆𝒓 𝒙 𝟏𝟎𝟎% OR 𝒏= 𝑰 𝟐 𝑽 𝟐 𝒄𝒐𝒔 𝜽 ( 𝑷 𝒄𝒐𝒑𝒑𝒆𝒓 + 𝑷 𝒊𝒓𝒐𝒏 ) + 𝑰 𝟐 𝑽 𝟐 𝒄𝒐𝒔 𝜽 𝒙 𝟏𝟎𝟎% V2 = Output voltage or secondary voltage I2 = Secondary current Cos = power factor at the load P copper = copper loss P iron = iron loss

5.0 APPLICATION OF POWER TRANSFORMER The most important uses and applications of a transformer are: It can rise or lower the level of level of Voltage or Current It can increase or decrease the value of capacitor, an inductor or resistance in an AC circuit. It can act as an impedance transferring device.   It can be used to prevent DC from passing from one circuit to the other.  It can isolate two circuits electrically

QUIZ CHECK ANSWER SCHEMES 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 : The secondary voltage 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 !