What sealing structure should be adopted for oil-immersed transformers?

Oil-immersed transformers play a crucial role in power systems, with their sealing performance directly impacting the operational reliability and lifespan of the transformers. The rationality and effectiveness of the sealing structure design are key factors in ensuring that the internal oil does not leak and external moisture does not penetrate the transformer. This article will discuss in detail the sealing structures that should be adopted for oil-immersed transformers.

1. Control of Compression Amount for Rubber Seals

   The sealing of oil-immersed transformers typically employs rubber seals, which achieve the sealing effect through the elasticity of the rubber. However, the compression amount of the seals must be strictly controlled to avoid sealing failure due to over-compression or under-compression. Generally, the compression amount of the seals should be controlled between 20% and 30%, with the optimal compression amount being 30%. For radial sealing structures, the ideal compression amount should be around 23%. Excessive compression can exceed the rubber's limit compression range, causing it to lose elasticity and fail to achieve effective sealing; insufficient compression cannot provide adequate sealing pressure, which will also lead to leakage problems.

2. Mechanical Connection of Flanges

   To ensure that the compression amount of the seals is within a reasonable range, large flanges should employ mechanical connections rather than elastic connections. Mechanical connections achieve this by adding grooves or limit blocks on the flanges, ensuring that the seals are evenly stressed during compression, thus avoiding sealing failure due to flange deformation. Mechanical connections ensure that the flanges have sufficient rigidity, maintaining the flatness of the sealing surface and the even stress on the seals even under significant force.

3. Cleanliness of Seals and Sealing Surfaces

   When installing the seals, it is essential to ensure that both the seals and the sealing surfaces remain clean. Any impurities or contaminants can affect the sealing effect, causing uneven stress on the seals during compression and ultimately leading to leakage problems. Therefore, before installation, the seals and sealing surfaces should be carefully cleaned to remove all particles and contaminants that might affect the sealing effect.

4. Common Sealing Structures

   Based on the aforementioned requirements, common sealing structures for oil-immersed transformers include the design of flanges with grooves. The groove depth on the flanges or the height of the limit blocks should be designed according to the specific dimensions of the seals and the required compression amount. In the table, parameter h represents the thickness of the sealing ring, d represents the diameter of the sealing ring, k represents the depth of the limiting groove or the height of the limiting block, and δ represents the compression amount of the seals.

The design of the sealing structure for oil-immersed transformers is critically important, directly affecting the operational reliability and lifespan of the transformers. By precisely controlling the compression amount of rubber seals, adopting mechanically connected flange designs, and ensuring the cleanliness of seals and sealing surfaces, effective sealing of the transformer can be achieved, thus preventing leakage problems. A reasonable sealing structure not only extends the service life of the transformer but also enhances the safety and stability of the power system.

LuShan, est. 1975, is a Chinese professional manufacturer specializing in power transformers and reactors for 49 years. Leading products are single-phase transformer, three-phase transformers, DC inductors, AC reactors, filtering reactor, expoxy resin high-voltage transformer and intermediate, high-frequency products. Our transformers and reactors are widely used in 10 application areas: rapid transit, construction machinery, renewable energy, intelligent manufacturing, medical equipment, coal mine explosion prevention , excitation system, vacuum sintering, central air conditioning.

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