Mutual Flux Vs Leakage Flux - How to reduced Leakage Flux? - Electronicsinfos

What are Mutual Flux & Leakage Flux?

When the transformer is under no load condition All primary Induced flux is passed through the iron core and links with secondary coils But when the transformer is in load condition it's reduced the magnetic path permanence which results in some primary flux is pass through the Air to complete the magnetic circuit. if we discuss an ideal transformer there is no magnetic leakage that occurs in the core but in cases of a Practical transformer, some flux passing through in the air to complete the magnetic circuit is called leakage flux.

Mutual Flux

The flux which is linked to both windings is called Mutual Flux and produced the secondary voltage or back emf.

In general, the greater the amount of mutual flux that is transferred between the windings, the more efficient the transformer will be. This is because the mutual flux represents the portion of the magnetic field that is used to transfer energy from the primary to the secondary winding. However, excessive mutual flux can also lead to saturation of the magnetic core material, which can result in losses and reduced efficiency.

Leakage Flux

The Flux which is linked only to one coil is called Leakage Flux. The effect of leakage flux is the same as External reactance. In small Units, The reactance is small as compared to the winding resistance but in large units, the reactance value is 10 times high as compared to winding resistance. On no load or light load, The MMF is small so we neglect the Leakage Flux but on high load, max current is flowing in the primary and secondary coils and produced high MMF which also increases the leakage flux.

Important Points

1. Leakage flux is only linked with one coil at a Time either primary or secondary.
2. Primary voltage provides supply to the reactive drops I1X1 or I1R1 and the same as I2X2 or I2R2.
3. In an actual Transformer, Primary and Secondary windings consist of One core to reduce the leakage flux.

How reduced Leakage Flux?

There are different methods used to reduce the Leakage Flux which are described below

Method of Reducing Leakage Flux

1. Making The T/F Window Long & narrow
2. Arranging The Windings Concentrically
3. Sandwiching The Both Windings
4. Using Shell Type Construction

Making The T/F Window Long & narrow

The window area h*w is always calculated w.r.t cross-sectional area of windings. To increase the reluctance path and height we decrease the leakage flux and the other method is to
decrease the width to reduce the leakage flux. practically there is some ratio in h and w that is limited to 4.

h/w = 4 In the case of a Practical transformer

Arranging The Windings Concentrically

To reduce the Leakage flux One method is used a concentric winding arrangement. In this method, we wind first low voltage winding(LWV) on the core and use insulation then wind high voltage winding(HVW).

Sandwiching The Both Windings

In this method, we use the sandwich method first we wind primary winding and surround it with both sides in secondary windings. we used more sandwich sections we need high Insulations In adjacent Sections.

Using Shell Type Construction

In this method, we used a Shell-type transformer in which The winding is used on the inner side and the core is used on the outer side.

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