Why is enameled wire used for the core (windings) of a transformer?

The core (windings) of a transformer uses enameled wire mainly due to the following technical reasons:

### 1. Requirements for Inter-turn Insulation

   - **Prevention of Short Circuits**: The winding is composed of multiple turns of wires tightly wound. 

The insulating paint on the surface of the enameled wire can effectively isolate adjacent wires, preventing

 short circuits caused by direct contact between turns.

   - **High Voltage Tolerance**: The insulating paint can withstand the high voltage differences during the 

operation of the winding (such as the high-voltage side winding), ensuring that the current only flows along

 the wire instead of leaking through the air or between conductors.

### 2. Efficient Electromagnetic Coupling

   - **Tight Winding**: The insulating layer of the enameled wire is extremely thin (usually only a few micrometers), 

allowing the wires to be closely arranged, reducing the volume of the winding and improving the utilization rate 

of the magnetic field of the iron core.

   - **Reduction of Leakage Inductance**: The closely arranged windings can enhance the electromagnetic coupling

 between the coils, reducing magnetic leakage and energy loss, and improving the efficiency of the transformer.

YouTube：https://youtube.com/shorts/Wakp7L3-dic

### 3. High Temperature Resistance and Aging Resistance

   - **Adaptability to High Temperature Environments**: When the transformer is in operation, heat is generated 

due to copper loss and iron loss. The insulating paint of the enameled wire (such as polyester, polyimide, etc.) can

 withstand temperatures above 130°C, avoiding insulation failure.

   - **Anti-oxidation and Moisture-proof**: The insulating layer protects the copper wire from oxidation and erosion

 by a humid environment, extending the service life of the winding.

### 4. Cost and Process Advantages

   - **Low-cost Manufacturing**: The production process of enameled wire is mature. The insulating layer is formed

 by painting and baking, which is more efficient and less costly than other insulation methods (such as wrapped 

with yarn or paper).

   - **Easy Processing**: The enameled wire has good flexibility and is suitable for automated winding equipment, 

especially for achieving high-density winding in small transformers.

### 5. Adaptation to Special Scenarios

   - **High-frequency Applications**: In high-frequency transformers, the insulating layer of the enameled wire can

 reduce the influence of the skin effect and the proximity effect, and lower the alternating current resistance.

   - **Special Environments**: Some enameled wires have the characteristics of oil resistance and corrosion resistance,

 making them suitable for harsh industrial environments.

### Limitations of Alternative Solutions

   - **Bare Wires**: Directly lead to inter-turn short circuits and cannot be used.

   - **Wires with Thick Insulation**: Increase the volume of the winding, reduce the number of turns and the magnetic

 field strength, and affect the performance.

   - **Other Insulating Materials**: Such as adhesive tapes and sleeves, the process is complex and it is difficult to 

achieve dense winding.

### Conclusion

The enameled wire solves the core requirements of the transformer winding - inter-turn insulation, efficient coupling, 

and reliability through its ultra-thin and high-temperature-resistant insulating layer. Its comprehensive performance 

and cost advantages make it the standard choice for transformer manufacturing.