- Properties of Aluminum Foil for Transformers
- Specifications of Aluminum Foil for Transformer
- Benefits of Aluminum Foil in Transformers
- Aluminium Foil For Transformer Winding Alloy Selection
- How Aluminum Foils used in Transformer?
- Manufacturing Process
- Transformer Winding
- Why do we use an Aluminum Foil Strip for HV Transformer Winding?
- Frequently Asked Questions (FAQ) about Aluminum Foil for Transformer Winding
- Conclusion
Aluminum foil plays a crucial role in the manufacturing of transformers, contributing significantly to their efficiency and performance.
Transformers are essential components in the electrical power distribution system, responsible for transforming voltage levels for transmission and distribution.
Properties of Aluminum Foil for Transformers
1. High Purity and Quality
Aluminum foil used in transformers is typically of high purity, often exceeding 99.5%. This ensures minimal impurities that could compromise the electrical properties of the foil.
2. Excellent Electrical Conductivity
Aluminum possesses excellent electrical conductivity, making it an ideal choice for transformer applications. High conductivity ensures efficient energy transfer within the transformer, minimizing energy losses.
3. Thermal Conductivity
Aluminum foil exhibits good thermal conductivity, aiding in the dissipation of heat generated during transformer operation. Efficient heat dissipation is crucial for maintaining the transformer's temperature within acceptable limits.
4. Formability and Flexibility
Aluminum foil is malleable and can be easily formed into the required shapes during the transformer winding process. Its flexibility allows for the creation of intricate winding patterns, optimizing the space within the transformer and enhancing its overall efficiency.
Specifications of Aluminum Foil for Transformer
| Alloy | 1050 1060 1070 1350 |
|---|---|
| Temper | O |
| Thickness | 0.2-3.5mm |
| Width | 20-1350mm |
| Quantity tolerance | ±10% |
| ID | 152.4, 200, 300, 400 and 500mm |
| Surface treatment | Mill finish |
| Application | Transformer winding |
| Packaging | Wooden Pallet |
Tolerance
| ALLOY-TEMPER | 1050-O, 1060-O, 1070-O | ||||
|---|---|---|---|---|---|
| Thickness | 0.2-0.4 | 0.4-0.8 | 0.9-1.1 | 1.2-1.6 | 1.8-2.5 |
| Tolerance | ±0.01 | ±0.015 | ±0.02 | ±0.025 | ±0.03 |
| Width | less than 100 | 100-200 | 201-500 | 501-1250 | >1250 |
| Tolerance | ±0.1 | ±0.2 | ±0.2 | ±1 | ±2 |
Tolerance Burr and Collapse
| THICKNESS OF ALUMINIUM STRIP | BURR’S HEIGHT | COLLAPSED SIDE’S HEIGHT |
|---|---|---|
| less than 0.2 | 0.01 | >0.05-0.1 |
| 0.2-1.0 | 0.015 | |
| 1.1-1.5 | 0.02 | |
| >1.6 | 0.03 |
Benefits of Aluminum Foil in Transformers
Lightweight
Aluminum is significantly lighter than copper, offering a weight advantage in transformer design and installation.
Cost-Effective
Aluminum foil is more cost-effective than copper, providing a balance between performance and economic considerations.
Corrosion Resistance
Aluminum exhibits natural corrosion resistance, ensuring the longevity and reliability of transformers in diverse environmental conditions.
Aluminium Foil For Transformer Winding Alloy Selection
Commonly used alloys include 1050, 1060, and 1070, known for their high electrical conductivity and formability.
1050 Aluminium Foil For Transformer Winding
- Electrical Conductivity: Transformer windings made of 1050 O in annealed condition is guaranteed to be better than 60 % ACS.
- Properties: High electrical conductivity, Good formability and weldability.
- Common Uses: Distribution transformers, Power transformers.
Examples:
Medium-sized distribution transformers used in local power distribution networks.
1060 Aluminium Foil For Transformer Winding
- Electrical Conductivity: Transformer windings made of 1060 O in annealed condition is guaranteed to be better than 61.5 % ACS.
- Properties: Excellent electrical conductivity, Good corrosion resistance.
- Common Uses: Power transformers, Instrument transformers.
Examples:
Large power transformers used in high-voltage transmission networks.
Instrument transformers for measuring current and voltage in substations.
1070 Aluminium Foil For Transformer Winding
- Electrical Conductivity: Transformer windings made of 1070 O in annealed condition is guar-anteed to be better than 62.7 % ACS.
- Properties: High electrical conductivity, Good formability.
- Common Uses: Power transformers, Distribution transformers.
Examples:
Large power transformers used in grid substations.
Distribution transformers for supplying electricity to residential and industrial areas.
1350 Aluminium Foil For Transformer Winding
- Electrical Conductivity: Transformer windings made of 1350 O in annealed condition is guaranteed to be better than 62 % ACS.
- Properties: High purity (99.5% or higher), Excellent electrical conductivity.
- Common Uses: High-voltage and extra-high-voltage transformers, Dry-type transformers.
Examples:
Extra-high-voltage transformers used in electricity transmission over long distances.
Dry-type transformers commonly found in indoor or sensitive environments.
Differences and Considerations
Purity: Alloy 1350 is known for its higher purity compared to the 1000 series alloys. This high purity is advantageous in applications where low levels of impurities are critical, such as in high-voltage and dry-type transformers.
Strength: Alloys 1050, 1060, and 1070 generally have higher strength compared to 1350. The choice of alloy may depend on the mechanical strength requirements of the specific transformer application.
Applications: Alloys 1050, 1060, and 1070 are commonly used in a wide range of transformers, including distribution and power transformers. Alloy 1350 is often chosen for applications where high purity is essential, such as in high-voltage and dry-type transformers.
Formability: Alloys 1050, 1060, and 1070 are known for their good formability, making them suitable for intricate winding patterns in transformer coils.
Corrosion Resistance: Alloy 1060 is known for its good corrosion resistance, which can be advantageous in environments where exposure to moisture is a concern.
The selection of a specific alloy depends on the transformer's design requirements, voltage class, and the desired balance of electrical, mechanical, and environmental properties.
How Aluminum Foils used in Transformer?
Aluminum foil is an integral component in the construction of transformers, and it serves specific purposes within different sections of a transformer. Here's how aluminum foil is used and where it is specifically employed in transformers:
Aluminum Foil for Winding Conductors
- Location: Primary and Secondary Windings
- Purpose: Aluminum foil is commonly used as a conductor material in the windings of transformers. It is wound in a layered configuration between the primary and secondary windings. The foil's high electrical conductivity ensures efficient energy transfer during the transformation of voltage levels.
Aluminum Foil for Layered Winding
- Location: Between Windings
- Purpose: The layered winding of aluminum foil helps optimize the magnetic flux within the transformer. The foil is interleaved with insulating materials to prevent short circuits and enhance the transformer's performance.
Aluminum Foil for Insulation
- Location: Between Windings and Around Conductors
- Purpose: Aluminum foil is often combined with insulating materials, such as paper or polymer films, to provide electrical insulation between winding layers. This prevents electrical breakdowns and ensures the reliable and safe operation of the transformer.
Aluminum Foil for Cooling and Heat Dissipation
- Location: Around Windings
- Purpose: Transformers generate heat during operation, and efficient heat dissipation is critical for their performance. Aluminum foil, with its good thermal conductivity, helps in the dissipation of heat, contributing to the temperature control of the transformer.
Aluminum Foil for Oil Immersed Transformers
- Location: Within the Transformer Tank
- Purpose: In oil-immersed transformers, where the transformer core and windings are immersed in insulating oil, aluminum foil may be used as a material for the fins or radiators. These fins increase the surface area exposed to the oil, facilitating better heat dissipation and maintaining the transformer's temperature within acceptable limits.
Aluminum Foil for Tank Construction
- Location: Transformer Tank
- Purpose: In some cases, aluminum foil may be used in the construction of the transformer tank itself. The foil can be part of the tank's design to provide structural integrity and contribute to the overall efficiency of the transformer.
Aluminum Foil for Conservator
- Location: Attached to the Transformer Tank
- Purpose: In transformers equipped with conservators, which are expansion tanks that accommodate oil volume variations due to temperature changes, aluminum foil may be employed as part of the flexible diaphragm or bladder within the conservator.
Aluminum Foil for High Voltage Insulation
- Location: Within High Voltage Bushings
- Purpose: Aluminum foil may be used as part of the insulation system within high voltage bushings, contributing to the electrical insulation and integrity of the transformer.
In summary, aluminum foil is strategically utilized throughout the various components of a transformer, from the windings and insulation to the tank and cooling systems. Its combination of electrical conductivity, thermal properties, and formability make it a versatile material for optimizing the performance and efficiency of transformers in diverse applications.
Manufacturing Process
1. Casting and Rolling
The selected aluminum alloy undergoes a casting process to create large ingots. These ingots are then hot-rolled into thin sheets, which serve as the basis for the transformer foil.
2. Annealing
The rolled aluminum sheets undergo an annealing process to enhance their softness and conductivity. Annealing involves heating the material to a specific temperature and then slowly cooling it to achieve the desired properties.
3. Surface Treatment
The surface of the aluminum foil may undergo treatment processes such as chemical cleaning or anodizing to improve its insulation properties and resistance to environmental factors.
Transformer Winding
Layered Winding
Aluminum foil is used in the winding process of transformers, forming layers between the transformer's primary and secondary windings. The layered configuration helps optimize the magnetic flux and reduces losses.
Insulation
Insulating materials are often interleaved with the aluminum foil to prevent short circuits and ensure the reliable performance of the transformer.
Why do we use an Aluminum Foil Strip for HV Transformer Winding?
The aluminum foils strips are used for high-voltage transformer with thickness and width ranges from 0.1mm to 3.0mm, and 10mm to 1370mm, respectively.
Generally, tempered aluminum alloy is used for HV transformers like 1060 O and 1070 O.
High-grade insulating foils are placed between aluminum foil strips. Mostly 1060 and 1070 alloys of aluminum are used to wind the high-voltage transformer windings.
The relatively high windings exhibit good ageing qualities under all operating conditions and corrosion-proof. For HV transformer windings, an aluminum foil strip provides a basic winding method with high electrical safety.
Frequently Asked Questions (FAQ) about Aluminum Foil for Transformer Winding
1. Why is aluminum foil used in transformer winding?
Aluminum foil is used in transformer winding due to its high electrical conductivity, formability, and thermal conductivity. It serves as a conductor in the transformer windings, facilitating efficient energy transfer.
2. What thickness of aluminum foil is suitable for transformer winding?
The thickness of aluminum foil for transformer winding varies based on the specific requirements of the transformer. It is typically in the range of 10 to 20 microns, but thicker foils may be used for certain applications.
3. How is aluminum foil protected during transportation and storage?
Aluminum foil for transformer winding is often protected with appropriate packaging materials such as moisture-resistant films and cartons. These materials shield the foil from moisture, dust, and other environmental factors.
4. What are the insulation properties of aluminum foil for transformer winding?
Aluminum foil may undergo treatments or have coatings to enhance its insulation properties. This is crucial to prevent electrical breakdowns within the transformer and ensure safe and reliable operation.
5. Can aluminum foil be used in all types of transformers?
Aluminum foil is commonly used in various types of transformers, including distribution transformers, power transformers, and instrument transformers. The specific alloy and thickness may vary based on the transformer's design and application.
6. How is the formability of aluminum foil maintained during packaging?
Proper handling and packaging techniques are employed to maintain the formability of aluminum foil. Packaging materials are chosen to avoid any damage or deformities to the foil during transportation and storage.
7. Are there specific standards for aluminum foil used in transformer winding?
Yes, there are industry standards and specifications that define the requirements for aluminum foil used in transformer winding. Manufacturers adhere to these standards to ensure the quality and performance of the foil in transformers.
Conclusion
In conclusion, aluminum foil is a fundamental component in the construction of transformers, contributing to their electrical and thermal performance. The careful selection of high-purity alloys, coupled with precise manufacturing processes, results in aluminum foil that meets the demanding requirements of the transformer industry.
As electrical systems evolve, the role of aluminum foil in transformers remains pivotal, enabling the efficient and reliable transmission of electrical power across the grid.