Hermetically Sealed Transformers are a specific type of transformer that doesn’t need a conservator or breather. These are fully sealed, and no air and no moisture can enter the tank, which helps to preserve the insulation of oil and extend the life of the transformer. In this article, we will explain hermetically sealed transformers, their design, functionality, advantages, and applications. Additionally, we will touch upon the importance of a “Transformer Oil Regeneration System” and the services for “Transformer oil regeneration based on IEC 60296 & IES 60422 standards” provided by INVEXOIL.
What is a Hermetically Sealed Transformer?
Hermetically sealed transformers are specialized electrical transformers with a sealed tank that contains the dielectric insulating fluid, usually oil. Unlike traditional transformers that use a conservator to accommodate oil expansion and contraction, hermetically sealed transformers have a fully sealed tank with flexible corrugated walls or fins to accommodate thermal expansion and contraction. This design ensures that no air or moisture can enter the tank, significantly reducing the risk of oxidation and degradation of the insulating oil.
Related Article: Understanding Transformer Oil Types for Optimal Performance and Sustainability
Hermetically Sealed Transformer Main Components are:
- Sealed Tank
- Insulating Oil
- Core and Windings
- Cooling System
- Pressure Relief
1. Sealed Tank:
- Material: High-grade steel for durability and environmental resistance.
- Thickness: Varies with the transformer size but usually 3 to 8 mm.
- Corrugated Fins: Flexible metal fins or corrugations are incorporated in the tank design to accommodate oil expansion and contraction due to temperature variation. The flexibility of the fins allows volume changes without compromising the seal integrity.
- Sealing Mechanism: The tank is hermetically sealed using advanced welding and sealing compounds to ensure a perfect seal. The tank tightness can be up to 0.5 Bar.
2. Insulating Oil:
- Type: Typically mineral oil, but synthetic or biodegradable oils can also be used based on specific applications.
- Quantity: Varies with the transformer size but usually hundreds to thousands of liters.
- Function: Provides electrical insulation and heat dissipation. No air prevents oxidation and preserves the oil’s insulation properties for a longer time.
Related Article: Comparative Analysis of Synthetic and Natural Ester Fluids
3. Core and Windings:
- Core Material: High-grade silicon steel laminations to minimize core losses and improve efficiency.
- Winding Material: Copper or aluminum, designed to handle high electrical load and minimize resistance losses.
4. Cooling System:
- Natural Cooling (ONAN): Utilizes the natural circulation of oil within the tank to dissipate heat.
- Forced Cooling (ONAF): Uses external fans or pumps to cool in high-load applications.
5. Pressure Relief:
- Pressure Relief Valves: Equipped with pressure relief valves to release excess pressure in case of internal fault or overheating.
Hermetically Sealed Transformer Operating Principles
Hermetically sealed transformers work on the same principles as regular transformers, with the primary winding getting power from the power source and the secondary winding delivering the output voltage to the load. However, the key difference lies in the sealed design and how it impacts the operation. Here’s a detailed explanation of the operating principles from beginning to end:
1. Initial Energization:
- Connect the primary winding to the power source and the transformer is energized. The magnetic field in the core induces a voltage in the secondary winding and the input voltage is transformed to the output voltage.
2. Heat Generation and Dissipation:
- During operation, electrical losses in the core and windings generate heat. The oil absorbs this heat and the flexible fins or corrugations on the tank allow natural convection to dissipate the heat to the surrounding environment. This keeps the transformer’s temperature within a safe operating range.
3. Oil Expansion and Contraction:
- As the transformer operates, the oil temperature changes, and it expands and contracts. The corrugated fins or flexible walls of the sealed tank accommodate these volume changes without letting air or moisture in. This prevents oxidation and maintains the oil quality.
4. Electrical Insulation:
- The oil provides electrical insulation between the core, windings, and the tank. The absence of air prevents moisture from forming which can degrade oil’s insulating properties. This ensures consistent electrical performance and reduces the risk of internal arcing or short circuits.
5. Pressure Management:
- The sealed tank design includes pressure relief valves that release excess pressure in case of internal faults or overheating. This ensures the safe operation of the transformer and prevents tank rupture.
Hermetically Sealed Transformer Benefits are
- Extended Lifespan
- Reduced Maintenance
- Improved Reliability
- Environmental Protection
- Cost-Effective
Hermetically sealed transformers have the following advantages over regular transformers:
1. Longer Life:
- The sealed design prevents air and moisture from entering the tank and reduces oxidation and corrosion. This maintains oil quality and extends transformer life.
2. Less Maintenance:
- The absence of a conservator and breather means that the transformer does not require regular maintenance. Ideal for applications where maintenance is difficult or costly.
3. More Reliable:
- Sealed design and high vacuum operation reduce oil leakage and moisture pressure.
4. Eco-Friendly:
- No oil leakage, no environmental pollution.
5. Cost Savings:
- Although the hermetically sealed transformer is more expensive than a regular transformer, the reduced maintenance and longer life can give you cost benefits in the long run.
Hermetically Sealed Transformer Applications are
- Chemical Manufacturing: Where maintenance is difficult, and the environment is harsh.
- Oil and Gas Terminals: Where moisture and dust are present.
- Power Distribution: To ensure reliable and efficient power supply.
- Marine and Offshore: To protect from marine environment.
Related Article: Comprehensive Guide to 17 Transformer Oil Regeneration Standards: Best Practices & Future Trends
Conclusion
Hermetically sealed transformers are a big leap in transformer technology, a reliable and efficient solution for various industrial applications. Their sealed design, low maintenance, and long life make them suitable for harsh environments and where maintenance is difficult. Understanding their design, functionality, and benefits will help users to optimize their performance and achieve their processing goals. Maintenance, troubleshooting, and upgrades/customization will ensure the optimal performance of these transformers.
These transformers exemplify the innovations in the energy sector, much like the advancements in Transformer Oil Regeneration Systems and the adherence to standards such as IEC 60296 & IES 60422 for oil regeneration services, ensuring the highest quality and reliability.
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