Question

Why Low Voltage winding near core of the Transformer?

Answer 1

In a transformer, the low-voltage (LV) winding is placed near the core for several important reasons, mainly related to efficiency, safety, and the overall design of the transformer. Here's why:

1. Minimizing the Leakage Flux:

   - Leakage flux refers to the magnetic flux that does not link both the primary and secondary windings of the transformer. This flux is undesirable because it reduces efficiency.
   - Placing the low-voltage winding near the core helps minimize leakage flux. This is because the low-voltage winding is exposed to a stronger magnetic field due to its proximity to the core. As a result, it becomes more efficiently magnetized, and the flux that links both windings is increased, reducing losses.

2. Reducing Voltage Stress:

   - The core of a transformer is typically grounded and carries a constant magnetic field. The high-voltage (HV) winding, which operates at higher potential, is typically placed on the outer side of the transformer to ensure better insulation and to reduce the electrical stress between turns and between winding layers.
   - The low-voltage winding, on the other hand, has a lower voltage potential and therefore does not need the same level of insulation. Placing it closer to the core helps in reducing the voltage stress on the winding insulation.

3. Physical Size and Heat Dissipation:

   - Low-voltage windings are usually thicker and have more turns compared to high-voltage windings because they carry higher current. Placing the low-voltage winding near the core helps in managing the physical space more efficiently.
   - Heat dissipation is another factor. The low-voltage winding typically handles more current and thus generates more heat. Being close to the core allows for better heat conduction away from the winding, making it easier to cool the transformer.

4. Magnetic Field Distribution:

   - The transformer’s core provides a path for the magnetic flux, and the field strength near the core is stronger. The low-voltage winding, which has more turns per unit length, benefits from being placed here because the magnetic field is more uniform and stronger, leading to better transformer performance.

5. Design and Safety Considerations:

   - By placing the low-voltage winding near the core, you can design the transformer to be more compact and easier to handle. Additionally, it ensures that the high-voltage winding, which needs more insulation and is more sensitive to leakage currents, is placed farther away from the core and grounded parts, improving safety.

Summary:

The low-voltage winding is placed near the core to improve efficiency, minimize losses due to leakage flux, reduce voltage stress, optimize space for winding thickness, and ensure better heat dissipation.