Explain the difference between leakage flux and main flux in a transformer core.

Explain the difference between leakage flux and main flux in a transformer core.

• A. Main flux links with both windings; leakage flux does not couple to the other winding; flows outside the desired path and causes leakage inductance.
• B. Leakage flux links with both windings; main flux does not couple to the other winding.
• C. Leakage flux is the same as main flux.
• D. Flux in the core contributes equally to both leakage and main.

Answer: (B)

In a transformer, the flux that links both windings is the main (mutual) flux. This is the portion of the magnetic field that completes the magnetic circuit through the core in a way that couples the primary and secondary, enabling the transformer action and mutual inductance between the windings. Leakage flux is the part of the magnetic flux that does not link the other winding. It follows paths that don’t complete through both windings (often circulating around one winding or fringing in the air gaps and around the winding region). Because it doesn’t couple to the other winding, it doesn’t contribute to the induced voltage on the other winding and instead shows up as leakage inductance in the model, reducing the ideal coupling between primary and secondary. So, main flux links both windings and drives the mutual coupling, while leakage flux does not link the other winding and exists as a separate, non-coupled path.

In a transformer, the flux that links both windings is the main (mutual) flux. This is the portion of the magnetic field that completes the magnetic circuit through the core in a way that couples the primary and secondary, enabling the transformer action and mutual inductance between the windings.

Leakage flux is the part of the magnetic flux that does not link the other winding. It follows paths that don’t complete through both windings (often circulating around one winding or fringing in the air gaps and around the winding region). Because it doesn’t couple to the other winding, it doesn’t contribute to the induced voltage on the other winding and instead shows up as leakage inductance in the model, reducing the ideal coupling between primary and secondary.

So, main flux links both windings and drives the mutual coupling, while leakage flux does not link the other winding and exists as a separate, non-coupled path.