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Transformer Operation


A transformer is an dectromagnetic device having two or more mutually coupled windings (share a common magnetic circuit). Figure 4 shows a two-winding, ideal transformer; the transformer is ideal in the sense that its core is lossless and is infinitely permeable, it has no leakage fluxes, and the windings have no losses.

Figure 4

In Figure 4, the basic components are the core, the primary winding, N1, and the secondary winding, N2. If Φ is ,the mutual (or core) flux threading each turn of N1 and N2, then according to Faraday´s law of electromagnetic induction, emfs e1 and e2 are induced in N1 and N2, given by

                 (Formula 9)

The direction of e is such as to produce a current that gives rise to a flux which opposes the flux change
 (Lenz´s law).  From (9),

e1/e2 = N1/ N2, or, in terms of rms values,

(Formula 10)

where a is the turns ratio.

The transformer being ideal, e1 = v1 and e2 = V2  in Fig. 4; hence the flux and voltage are related by

    (Formula 11)

If the flux varies sinusoidally, Φ = Φm sin ωt, then the corresponding induced voltage, e, in an N-turn winding is given by

e = ωN Φmcosω(13.12)
and the rms value of this induced voltage is


which is known as the em! equation. In (13),   j = ω/2л is the flux frequency in Hz.

Keywords : Transformer, Operation, Energy, Magnetic, Induction, Transformer, Transformation, Electrical, Electronic
Writer : delon  |
16 Mar 2006 Thr   
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