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PRESENTATION ON BASIC OF TRANSFORMER <ul><li>Presented to: </li></ul><ul><li>Engr.A.H.M. Mohiuddin </li></ul><ul><li>Presented by: </li></ul><ul><li>Md. Anik Arefin Nahin(081-19-846) </li></ul><ul><li>Syed Afiat Rahman(081-19-845) </li></ul><ul><li>Borni Mohanta(081-19-848) </li></ul><ul><li>Monalisha Mishu(081-19-847) </li></ul><ul><li>Dept. of ETE; DIU </li></ul>

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Present Presenter Md. Anik Arefin Nahin 081-19-846

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Transformer

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What is Transformer ??? <ul><li>A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled electrical conductors. </li></ul><ul><li>Transformer is used to convert high alternatic voltage,current or power level to low alternatic voltage,current or power level and vice versa. </li></ul>

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Construction <ul><li>A transformer consists of a rectangular core of soft iron in the form of sheets insulated from one another. Two separate coils of insulated wires, a primary coil and a secondary coil are wound on the core. These coils are well insulated from one another. The coil on the input side is called primary coil and on the output side is called secondary coil. </li></ul>

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Main parts of a transformer

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<ul><li>Piece Function </li></ul>Protects the above components from dirt, moisture and mechanical damage. Enclosure Receives energy from primary winding and delivers it to the load Secondary Winding Receives the energy from the ac source and creates magnetic field. Primary winding Provides a path for magnetic lines of flux. Core

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Next Presenter Borni Mohanta 081-19-848

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Working Principle

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Working Principle <ul><li>Transformer basically works on the principle of mutual induction of two coils. A changing current in the first circuit (the primary ) creates achanging magnetic field. </li></ul><ul><li>This changing magnetic field induces a changing voltage in the second circuit (the secondary ). This effect is called mutual induction. </li></ul>

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<ul><li>If a load is connected to the secondary circuit, electric charge will flow in the secondary winding of the transformer and transfer energy from the primary circuit to the load connected in the secondary circuit. </li></ul>

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<ul><li>Let the primary voltage is V p </li></ul><ul><li>and induced voltage is V s </li></ul><ul><li>According to Faradays law, for primary coil </li></ul><ul><li> V p =N p ΔΦ / Δ t ---------(1) </li></ul><ul><li>Similarly for secondary coil </li></ul><ul><li> V s =N s ΔΦ / Δ t ---------(2) </li></ul><ul><li>Dividing (1) by (2) </li></ul><ul><li>V p / V s =N p / N s </li></ul><ul><li>Ns = Number of turns of primary coil </li></ul><ul><li>Np= Number of turns of secondary coil </li></ul>

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<ul><li>This equation shows that the magnitude of EMF depends upon the number of the turns in the coil. </li></ul>

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Next Presenter Syed Afiat Rahman 081-19-845

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Types of transformer

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Types <ul><li>There are generally two types of transformer </li></ul><ul><ul><ul><ul><ul><li>Step up transformer </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Step down transformer </li></ul></ul></ul></ul></ul><ul><li>Some important types are given as: </li></ul><ul><ul><ul><ul><ul><li>Auto-transformer </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Poly-phase transormer </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Leakage transformer </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Resonant transformer </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Instrument transformers </li></ul></ul></ul></ul></ul>

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Step up transformer <ul><li>A step up transformer is a device that converts low alternatic voltage to high alternatic voltage. </li></ul><ul><li>In another word, a transformer in which Ns>Np that is called step up transformer. </li></ul>Np Ns

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Step down transformer <ul><li>A step up transformer is a device that converts high alternatic voltage to low alternatic voltage. </li></ul><ul><li>In another word, a transformer in which Np>Ns that is called step up transformer. </li></ul>

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AUTO-TRANSFORMERS <ul><li>An autotransformer with a sliding brush contact </li></ul><ul><li>An autotransformer has only a single winding with two end terminals, plus a third at an intermediate tap point. </li></ul>

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POLY-PHASE TRANSFORMER <ul><li>For three-phase supplies, </li></ul><ul><li>A bank of three individual single-phase transformers can be used, </li></ul><ul><li>OR all three phases can be made as a single three-phase transformer. </li></ul>

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INSTRUMENT TRANSFORMERS <ul><li>Current transformers, designed to be looped around conductor. </li></ul><ul><li>A current transformer is a measurement device </li></ul><ul><li>provide a current in its secondary coil proportional to the current flowing in its primary. </li></ul>

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RESONANT TRANSFORMERS <ul><li>A resonant transformer is a kind of the leakage transformer. </li></ul><ul><li>It uses the leakage inductance of its secondary windings in combination with external capacitors, </li></ul><ul><li>To create one or more resonant circuits. </li></ul>

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Other types of transformers <ul><li>Power Transformer </li></ul><ul><li>Distribution Transformer </li></ul><ul><li>Dry Type Transformer </li></ul><ul><li>Furnace Transformer </li></ul><ul><li>OLTC Transformer </li></ul><ul><li>Servo Stabilizer </li></ul>

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Next Presenter Monalisha Mishu 081-19-847

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Induction Law and Ideal Power Equiation

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Induction law <ul><li>Faraday’s law states that: </li></ul><ul><li>Vs=Ns.d Φ /dt </li></ul><ul><li>where VS is the instantaneous voltage. </li></ul><ul><li>NS is the number of turns in the secondary coil. </li></ul>

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<ul><li>Since the same magnetic flux passes through both the primary and secondary coils in an ideal transformer,the instantaneous voltage across the primary coil </li></ul><ul><li>Vp=Np.d Φ /dt </li></ul>

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<ul><li>Taking the ratio of the two equations </li></ul><ul><li>for Vs and Vp gives the basic </li></ul><ul><li>equation for stepping up or stepping </li></ul><ul><li>down the voltage </li></ul>

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Ideal Power Equation <ul><li>Now if the secondary coil is connected to a load that allows current to flow, electrical power will transmitted from the primary circuit to the secondary circuit. </li></ul><ul><li>Ideally, the transformer is perfectly efficient. Incoming power is equal to the outgoing power. </li></ul><ul><li>P in =I p V p = P out =I s V s </li></ul>

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<ul><li>Ideal transformer equation </li></ul><ul><li>V p / V s = N p / N s = I s / I p. </li></ul><ul><li>An ideal transformer would have no energy losses, and would be 100%. </li></ul><ul><li>But practically we get 95% to 98% for larger transformers. </li></ul>

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Thank You…